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Welded connections. The calculation is intended for the
geometrical design and strength control of statically loaded welded
connections of machine structures manufactured from carbon steels.
The program enables you to design over 50 of the most common types
of welded connections stressed by various combinations of load. The
calculation deals with the following tasks:
1. Design of connections with butt welds. 2. Design of
connections with fillet welds. 3. Design of connections with plug
and slot welds. 4. Design of connections with spot (resistance)
welds. 5. Strength control of designed connections. 6. The program
includes a table with approx. 700 carbon steels suitable for
welding according to the material standards ANSI, EN, JIS, ISO,
DIN, BS, NF, UNI, UNE, SIS, CSA, NBN, NP,
NS, ON and CSN. 7. The program also includes a dimensional table
of steel sections S, ST, W, WT, C, L according to ASTM/AISI/AISC
and T, I, U, L sections according to DIN/EN/ISO.
The calculation is based on data, procedures and algorithms from
specialized literature and standards AWS, AISC, ANSI, EN, ISO, DIN
and others.
List of standards: prEN 1993-1-8, EN 10024, EN 10034, EN 10055,
EN 10056, EN 10279, DS 952, DIN 15018, DIN 18800, DIN 1024, DIN
1025, DIN 1026, DIN 1028, DIN 1029, CSN 050120
Note: This calculation is not intended for the design and
control of some special welded structures subject to special
standards, regulations and provisions (e.g. pressure vessels,
pipelines, cranes, ...).
Control, structure and syntax of calculations. Information on
the syntax and control of the calculation can be found in the
document "Control, structure and syntax of calculations".
Information on the project. Information on the purpose, use and
control of the paragraph "Information on the project" can be found
in the document "Information on the project".
Theory - Fundamentals. The welded connections are solid,
non-detachable connections based on the principle of local melting
of connected parts using heat or pressure. The joining of
components proper may be achieved technically using two
methods:
Fusion welding (arc, flame, plasma, laser, thermite,
electroslag, ... welding) The weld is a result of local melting of
the material of connected parts, and usually also filler metal,
without pressure.
Pressure welding (resistance, induction, ultrasonic, friction,
explosion, ... welding) After melting in, the components join in
the contact spot using mechanical pressure or impacts.
An optimum result of the welding process should be a weld with
mechanical properties similar as far as possible to the properties
of the basic material. According to their function, we can divide
welds into:
Force welds - load-bearing welds used to transfer external load
Tack welds - welds providing only compactness of the whole (with no
or negligible external load) Caulk welds - welds providing
staunchness of connected parts (vessels, pipelines, etc.)
This program is designed for the calculation of statically
loaded welded connections of machinery structures manufactured from
carbon steels, for working temperatures ranging from -20 to 150C.
The program enables you to perform geometrical design and strength
checks of force connections with the most common types of fusion
welds and connections with spot resistance welds. The calculation
does not consider the sudden formation of fragile fractures, change
in material properties due to temperature, impact of own tensions
or concentration of stress in the weld.
An accurate theoretical solution to force and strength
conditions is an extremely complicated problem for welded
connections, even for welds with simple shapes. That is why common
technical calculations are based on a range of conventions and
simplified premises. In view of the strength checks, welded parts
are usually considered a single compact part with a dangerous spot
(section) in the welded area. On the grounds that there is an even
distribution of stress in the active weld section, only theoretical
rated stress in the specified section is specified for the
respective load, regardless of the technological workmanship of the
weld or potential internal tension. For connections with multiple
welds, an even load on individual welds is assumed.
The strength checks of the connection are performed by simple
comparison of the calculated rated stress with the permissible
stress in the weld. Permissible weld stress "SwA" is usually
specified from the value of the yield strength of the basic
material "Re" based on the required safety.
When selecting the safety coefficient "FS", it is necessary to
consider the specific factors of welded connections in addition to
the general principles used to specify the safety coefficients. The
required safety degree should respect all the facts that were not
considered in the calculation of rated stresses (technological
workmanship of weld, weld quality, internal tension, weld
homogeneity, shape and finish of weld surface, weld reinforcement,
ignites and penetrations, etc.). Last but not least, the direction
of stress and the anisotropic properties of material in the weld
must also be considered. Different weld material properties in the
vertical and horizontal direction result in differing values of the
safety coefficient depending on the type, workmanship and load type
of the welded connection.
From the above mentioned, it is obvious that the most
complicated task in strength checks of the welded connection
applies to the proper choice of safety coefficient. General
procedures for setting safety coefficients can be found in the
document "Coefficients of safety", while specific recommendations
regarding welded connections are given at the end of the chapter.
The procedures to specify the rated stress for individual types of
welds are detailed in the following paragraphs.
Butt welds. Butt welds originate in the joint gap of connected
parts and are usually used as load-bearing, force welds. In order
to achieve perfect workmanship of the welds, it is usually
necessary to perform modification of the contact surfaces of the
connected parts. The method of welded surface treatment is set by
the workmanship of the connection, the thickness of the welded
parts, the welding method and the accessibility of the welded
spot.
When designing and performing the strength checks of welded
connections, the weldment with a butt weld is considered as a solid
component with a dangerous spot in the area of the weld. The
load-bearing weld section will be the basic characteristic of the
connection for the assessment of its load-bearing capacity.
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In the calculation of butt welds, the type of welds (method of
weld surface treatment) or potential weld root reweldment are not
considered. The load-bearing section of the butt weld is then
specified only by its thickness "a" and length "L".
Note: This program is designed for the calculation of
connections with uniform, fully penetrated butt welds. The
recommended procedures for handling special cases of connections
(partly welded welds, intermittent welds, combined welds) can be
found at the end of this chapter.
Weld throat thickness: In order to specify the load-bearing
section, the thickness of the thinner of the welded parts is
considered as the butt weld throat thickness "a". Reinforcement of
the weld surface and root is not considered.
Effective weld length: In a normal type of weld, so-called "end
down-slopes" are formed. They result in weakening of the section at
the weld's beginning and end. The effective weld length will then
be smaller than the actual length (reduced by a worse-quality weld
beginning and end). For more accurate calculations, we therefore
recommend controlling the load-bearing capacity of welds only for
that part (length) of the weld that has a rated section. The common
method of setting the effective length "L" for common weld
execution (fig. a) and specially treated welds (fig. b) is
described schematically in the picture.
Hint: This program is provided with the function of automatic
effective weld length calculation - see the switch on line
[2.6].
Strength solution of welds: When performing strength checks of
butt welds, the rated stress in the load-bearing weld section must
be specified first. Depending on the respective load, the
individual stress components are specified in the direction normal
to the weld and in the direction parallel to the weld (ll). The
calculated rated stresses must not exceed the values for the
permissible stress.
When specifying permissible stresses, the anisotropic properties
of the material in the area of the weld must be considered.
Different properties of the material result in differing values of
permissible stress of the weld in the normal and parallel
direction.
For connections stressed by combined load, the resulting
"equivalent" stress in the weld is specified from the relation:
which for ll= 0 can be adjusted as:
The following table specifies the relations used in the
calculation of rated stresses (for respective load and workmanship
of the connection):
Load Rated stress [MPa, psi]Tensile/Press.
Shear
Bend
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where: a .... weld throat thickness [mm, in] Aw ... weld throat
area [mm
2, in2]
D .... tube diameter [mm, in] .... weld angle [] F .... acting
force [N, lb] Fn ... normal force [N, lb]
Fs ... shear force [N, lb]
L .... effective weld length [mm, in] M .... bending moment [N
mm, lb in] ... normal stress vertical to the weld direction [MPa,
psi] ll ... normal stress parallel to the weld direction [MPa, psi]
T .... torque [N mm, lb in] ... shear stress vertical to the weld
direction [MPa, psi] ll ... shear stress parallel to the weld
direction [MPa, psi] Zw ... module of weld section [mm
3, in3]
Connections with partly welded welds: Connections with partly
welded butt welds are usually handled as fillet welds, with the
weld throat (effective) thickness "a".
The other, less appropriate solution method applies to the use
of the normal calculation of butt welds with the weld throat
thickness "2a" and adequately increased safety degree.
Connections with combined welds: Connections with a combined
butt and fillet weld are usually handled as butt welds with the
weld throat (efficient) thickness "a".
Bend
Twist
Tensile
Tensile/Press.
Shear
Bend
Tensile/Press.
Shear
Bend
Twist
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Weld throat thickness:
where for:
Connections with intermittent welds: This program is not
primarily modified to handle connections with intermittent weld.
Therefore use the following steps for their calculation:
1) Uncheck the switch on line [2.6] 2) For welds loaded only in
one direction (subject to tension or shear), check the connection
for the effective weld length L=L''. 3) For connections stressed by
bend, twist or combined load, check the connection for full weld
length L=L', while the required weld safety must be multiplied by
the ratio of lengths L'/L''. Recommendation: We do not recommend
the use of intermittent welds for connections with butt welds.
Fillet welds. Fillet welds are located along the wedge-shaped
edge of connected parts and their basic cross-section includes an
isosceles rectangular triangle. They are usually used for
load-bearing, force welds in T-shape connections, cross-butt
connections, angle connections and for lap joints. The welded parts
do not need shape adjustment. For statically loaded connections,
usually a flat weld is used, while a concave weld is more
appropriate for dynamically loaded connections, as it has lower
notch effects.
In strength checks of fillet welds, the rectangle lying in the
centre plane dividing the weld section into two identical parts is
considered the dangerous (load-bearing) weld section. The
dimensions of the load-bearing section of a fillet weld are
specified by its thickness "a" and length "L".
Note: This program is designed for the calculation of welds with
uniform fillet welds. The recommended methods of handling
connections with intermittent welds or with combined welds can be
found at the end of this chapter.
Weld throat thickness: The fillet weld throat thickness "a" is
defined as the height of the biggest isosceles triangle inscribed
into a weld section without penetration.
Recommendation: The fillet weld thickness is chosen depending on
the used material and thickness of the welded parts. As the
information regarding the recommended weld thickness given in the
literature differs significantly, follow the company procedures in
choosing the weld thickness. In order to specify the approximate
minimum thickness of the fillet weld, the following informative
relation can be used for the steel strength Rm370..420 MPa:
with tmin for thickness of the thinner of the connected
materials. For steels with higher strength (Rm520 MPa), the weld
thickness should be approx. 1 to 2 mm higher. Effective weld
length: In a normal type of weld, so-called "end down-slopes" are
formed. They result in weakening of the section at the weld's
beginning and end. The effective weld length will then be smaller
than the actual length (reduced by a worse-quality weld beginning
and end). For more accurate calculations, we therefore recommend
controlling the load-bearing capacity of welds only for that part
(length) of the weld that has a rated section. A common method of
specifying the effective length "L" depending on the weld
workmanship is shown schematically in the picture.
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Hint: This program is provided with a function of automatic
effective weld length calculation - see the switch on line [3.12]
or [4.12].
Recommendation: The length of the fillet weld should range
between 5a< L< 70a. For longer welds, it is more practical to
use an intermittent weld. For very long welds (150a
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Jw ... polar moment of inertia of the weld [mm4, in4]
... normal stress vertical to the weld direction [MPa, psi] ll
... normal stress parallel to the weld direction [MPa, psi] ...
shear stress vertical to the weld direction [MPa, psi] ll ... shear
stress parallel to the weld direction [MPa, psi]
For connections stressed by combined load, the resulting
"equivalent" stress in the weld is specified from the relation:
which for ll= 0 can be adjusted as:
The sectional properties for the selected basic shapes of weld
groups can be found in the following table. In order to specify the
polar moment of inertia of the weld, you can use the following
relation:
where: a .... weld throat thickness [mm, in] B .... width of
weld group [mm, in] D .... weld diameter [mm, in]
Shape Aw [mm2, in2] IwX [mm
4, in4] IwY [mm4, in4]
Centre of gravity of weld group:
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H .... height of weld group [mm, in] L .... weld length [mm, in]
s .... flange thickness [mm, in] t .... web thickness [mm, in]
Connections with combined welds: Connections with a combined
butt and fillet weld are usually handled as butt welds with the
weld throat (efficient) thickness "a".
Weld throat thickness:
where for:
Connections with intermittent welds: This program is not
primarily modified to handle connections with intermittent weld.
Therefore use the following steps for their calculation:
1) Uncheck the switch on line [3.12, 4.12] 2) For welds loaded
only in one direction (subject to tension or shear), check the
connection for the effective weld length L=L''. 3) For connections
stressed by bend, twist or combined load, check the connection for
full weld length L=L', while the required weld safety must be
multiplied by the ratio of lengths L'/L''.
Plug and slot welds. Plug and slot welds are usually used for
lap joints. They are not suitable for the transfer of high forces
and are especially not suitable for dynamically loaded connections.
The connection is formed by the weld on walls of circular or oval
openings and in the contact surface of the adjoining part. Plugs
and slots of small dimensions are usually fully filled with the
weld.
These welds are not suitable for the joining of thicker plates
and are usually used for thinner plates up to approx. 15 mm thick.
In view of the stress, slot welds are more preferable due to the
better quality of penetration of the weld root. A better quality of
the weld, i.e. better strength characteristic of the joint, can be
achieved by sloped walls of openings.
Recommended weld dimensions: Hole diameter ... d 2s Slot width
... d 2s Slot length ... L 2d Strength solution of welds: Two types
of damage appear in plug and slot welds: 1) shear in the weld base
surface 2) tear in the weld circumferential surface
During strength checks, both possible types of damage must be
assessed. We can specify the resulting rated stress from the
relation:
Shear stress in the base surface of the weld:
Shear stress in the circumferential surface of the weld:
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The sizes of calculated weld surfaces Aw are specified for both
weld types in the table:
where: F .... acting force [N, lb] d .... plug weld diameter, or
slot weld width [mm, in] i ..... number of welds L .... slot weld
length [mm, in] s .... plate thickness [mm, in]
Spot (resistance) welds. Spot resistance welds are usually used
to connect thin plates and thin-walled parts. They are especially
very useful in lot production. The connections with spot welds are
not very appropriate for transferring high forces. In view of the
type of stress, we distinguish two basic types of connections with
spot welds: - connections with welds stressed in shear (lap joints)
- connections with welds stressed in tear (by tension)
In technical practice, not more than 3 parts with maximum total
thickness up to approx. 15 mm are allowed to be joined for
connections with resistance welds. The thickness ratio for
individual parts should not exceed 1:3. The welds should be
positioned towards the external force so that they are always only
stressed in shear. Spot welds stressed in tension have
significantly lower load-bearing capacity, which is why their use
is not recommended. Lap welds can be made as single-shear or
double-shear. A minimum of 2 and maximum of 5 spot connections
should be located in the direction of acting force.
Recommended weld dimensions: Spot weld diameter ... d 5 s0.5
Pitch between adjacent welds ... t1 (2..3) d Weld distance from
edge of plate ... t2 2d Strength solution of welds: During strength
checks, the following checks are carried out for spot welds: 1)
Check of weld against tear in cylindrical area 2) Check of weld
against shear (for lap joints) 3) Check of weld against separation
(for welds stressed in tension)
The calculation is based on the assumption of evenly distributed
force F on all welds. We can specify the resulting rated stress
from the relation:
Shear stress in the cylindrical area of the weld:
Shear stress in the weld throat area:
Normal stress in the weld throat area:
where: Awa ... area of the spot weld section [mm
2, in2]
Awc ... cylindrical area of the weld [mm2, in2]
F .... acting force [N, lb] d .... spot weld diameter [mm, in] i
..... number of welds s .... plate thickness [mm, in]
Safety of welded connections, used calculation methods. An
accurate theoretical solution to force and strength conditions is
an extremely complicated problem for welded connections, even for
welds with simple shapes. That is why common technical calculations
are based on a range of conventions and simplified premises. That
logically results in certain disagreement between the solution
models commonly used in practice.
Plug welds Slot welds
Base area of weld [mm2, in2]
Circumferential area [mm2, in2]
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That is why the program is provided with an option to select
from three different calculation methods.
Although all three specified methods use almost a similar way of
theoretical handling of tension in the examined spot of the weld,
they differ in the method of evaluating the total load-bearing
capacity of the designed connection. That is why each calculation
method operates with its own safety rate differing in quality. The
choice of an appropriate method will then depend on the user's
specific requirements and experience.
The following paragraphs provide a detailed description of
individual calculation methods.
1. Basic calculation method. This method represents a general
method of handling welded connections and is based on the most
frequent calculation methods for welded connections of machinery
equipment mentioned in the literature.
Depending on the respective type, workmanship and load of the
welded connection, this method calculates the respective
theoretical rated stress in the load-bearing weld section (normal,
shear, or equivalent) in the first step. The strength checks of the
weld are then performed by simple comparison of the calculated
stress to the yield strength of the basic material. With respect to
the type of calculated stress, we can describe the conditions of
the load-bearing capacity of the weld using the following
relations:
The required safety of the weld stress is then the ratio between
the value of the yield strength of the basic material and the value
of the maximum admissible stress of the specific weld.
This method is disadvantageous due to the rather complicated
procedure in specifying the suitable safety rate minimum value. In
addition to the common (qualitative) criteria, specific factors of
the specific welded connection (type, workmanship and the way of
connection load) must be considered when choosing the required
safety. The required safety for the yield strength "FSy" is then
defined as the product of two safety coefficients FSy = FS1 *
FS2.
Safety coefficient FS1: Depends on the direction of the acting
stress and the anisotropic properties of the material in the
examined weld spot. Its value should also consider the
technological weld parameters. With respect to the type,
workmanship and the way of connection load, it is chosen from the
range 1 to 2.
Safety coefficient FS2: It considers qualitative parameters.
With respect to the accuracy and value of input information,
connection importance, production quality, operating conditions and
calculation accuracy, it is usually chosen from 1.1 to 2.
Hint 1: You can find the informative values for the choice of
safety coefficients FS1 and FS2 in chapter [1.3] of the Help.
Hint 2: This method is suitable for experienced users who are
able to perform a sound design of the required safety degree
depending on the specific type, workmanship and load of the welded
joint.
2. Method of conversion coefficients. This method expands the
basic calculation method and brings certain simplification to the
area of considering the designed joint load-bearing capacity. As in
the previous method, the respective theoretical rated stresses in
the load-bearing weld section are calculated first. In the next
step, the resulting comparative stress is defined based on these
rated stresses using the predefined empirically set conversion
coefficients. These coefficients consider the anisotropic
properties of weld material in the direction of the acting stresses
and their size will therefore depend on the type, workmanship and
the way of load of the welded joint.
Depending on the acting stress, the resulting comparative stress
will be specified for the respective conversion coefficients ""
from the following relations: - in linear state of stress
- in multi-axial stress of butt welds
- in multi-axial stress of fillet welds
The strength checks of the weld are then performed by comparison
of the calculated comparative stress to the yield strength of the
basic material. Regardless of the type, workmanship or the way of
load of the welded joint, we can describe the condition of
load-bearing capacity using a single relation:
The required safety against the yields point "FSy" will consider
only the qualitative parameters of the welded connection for this
method. With respect to the accuracy and value of input
information, connection importance, production quality, operating
conditions and calculation accuracy, it is usually chosen from 1.1
to 2.
Hint 1: You can find the informative values for the choice of
safety coefficient FSy in chapter [1.5] of the Help. The values of
the predefined conversion coefficient may be adjusted in paragraph
[3.1] on the sheet "Options".
Hint 2: This method is especially suitable for less experienced
users. Its use may be advantageous in case of a comparative
calculation when several designed solutions with a different type
of weld need to be compared.
3. Method of permissible stresses. The most complicated task in
the strength checks of welded connections usually applies to
defining the correct value of the permissible weld stress. The
logical result is therefore the fact that it is this area of
specifying the permissible stresses where the most noticeable
differences between various recommended procedures used in
technical practice appear.
The previous calculation methods control the load-bearing
capacity of the joint by simple comparison of calculated stresses
to the yield strength of the basic material. They do not provide
for direct handling of the requirement of strength checks for the
known values of permissible weld stress prescribed by the standards
or company procedures. This method therefore obliges users who want
to use this program to design the joint and at the same time comply
with the prescribed procedures for the strength checks.
Unlike the previous method, this method uses the comparison of
calculated stresses to the value of permissible stress "SwA"
defined directly by the user for strength checks. The condition of
load bearing capacity of the welded connection may then be
described using the relation:
As the required safety level is usually already included in the
value of the prescribed permissible stress, the applied safety
degree "FS" is used as an auxiliary quantity and only describes a
certain degree of "over-dimensioning" of the designed connection.
The safety value "FS" will then depend on the procedure applied by
the user in order to define the permissible stress, and it is
usually FS1. Hint 1: Some values of permissible stresses that are
specified in professional literature are derived for a different
methodology of comparative stresses calculation. That is why this
method enables variable behaviour of the calculation. Set the basic
parameters for the calculation of comparative stresses in paragraph
[3.10] on the sheet "Options".
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Hint 2: Use this method if you need to check the load-bearing
capacity of the welded connection for known (rated) permissible
connection stress.
Process of calculation. A typical calculation / connection
design includes the following steps:
1. Set the required calculation units (SI / Imperial). [1.1] 2.
Choose the proper calculation method and set the required safety
level [1.2]. 3. Choose the material for the connected parts [1.9].
4. Select the chapter with the respective type of welded
connection. 5. On the first line of the chapter [X.1] select the
required workmanship (shape) of the connection. 6. In paragraph
[X.2] set the dimensions of the connected parts. 7. Check the
respective check boxes in the paragraph "Loading of the connection"
to select the appropriate load combination. Specify the size of the
selected loads. 8. Check the calculated safety of the designed
connection in the paragraph "Strength checks of the connection". 9.
Save the workbook with the satisfactory solution with a new
name.
Basic parameters of the calculation, connection material. [1]
Use this paragraph to set the control parameters for the
calculation (calculation method and calculation units) and choose
the appropriate material for the connected parts.
1.1 Calculation units. In the selection list, choose the desired
calculation unit system. All values will be recalculated
immediately after switching to other units.
1.2 Used calculation method. An accurate theoretical solution to
force and strength conditions is an extremely complicated problem
for welded connections, even for welds with simple shapes. That is
why common technical calculations are based on a range of
conventions and simplified premises. That logically results in
certain disagreement between the solution models commonly used in
practice. That is why the program is provided with an option to
select from three different calculation methods.
Although all three specified methods use almost a similar way of
theoretical handling of tension in the examined spot of the weld,
they differ in the method of evaluating the total load-bearing
capacity of the designed connection. That is why each calculation
method operates with its own safety rate differing in quality. The
choice of an appropriate method will then depend on the user's
specific requirements and experience.
Select the appropriate calculation method using the appropriate
switch. Define the required connection safety for the selected
method.
Hint 1: You can find a description of individual calculation
methods and recommended safety values in the respective notes or in
the theoretical part of the Help.
Hint 2: General procedures of determination of safety
coefficients can be found in the document "Coefficients of
safety".
1.3 Basic calculation method. This method represents a general
method of handling welded connections and is based on the most
frequent calculation methods for welded connections of machinery
equipment mentioned in the literature.
Depending on the respective type, workmanship and load of the
welded connection, this method calculates the respective
theoretical rated stress in the load-bearing weld section (normal,
shear, or equivalent) in the first step. The strength checks of the
weld are then performed by simple comparison of the calculated
stress to the yield strength of the basic material. The required
safety of the weld stress is then the ratio between the value of
the yield strength of the basic material and the value of the
maximum admissible stress of the specific weld.
This method is disadvantageous due to the rather complicated
procedure in specifying the suitable safety rate minimum value. In
addition to the common (qualitative) criteria, specific factors of
the specific welded connection (type, workmanship and the way of
connection load) must be considered when choosing the required
safety. The required safety for the yield strength "FSy" is then
defined as the product of two safety coefficients FSy = FS1 *
FS2.
Safety coefficient FS1: Depends on the direction of the acting
stress and the anisotropic properties of the material in the
examined weld spot. Its value should also consider the
technological weld parameters.
Information values for the choice of safety coefficient FS1:
Safety coefficient FS2: It considers qualitative parameters.
With respect to the accuracy and value of input information,
connection importance, production quality, operating conditions and
calculation accuracy, it is usually chosen from 1.1 to 2.
Information values for the choice of safety coefficient FS2:
Note: For connections operating in a corrosive environment or at
high temperatures, higher values for safety coefficient FS2 are
also used.
Butt welds- subject to compression 1- subject to tension /
bending 1 ... 1.2- subject to shear 1.4 ... 1.5* higher values -
one-sided welded welds, unworked welds, manual arc or flame
welding
* lower values - double-sided welded welds, worked welds and
welds with rewelded root, automatic welding in CO2 or under welding
flux, electroslag welding
Fillet welds- end welds 1.2 ... 1.5- side welds 1.3 ... 1.6*
higher values - flat welds, unfinished welds, welds without
penetration, thicker welds, manual welding
* lower values - concave welds, penetrated welds,
lower-thickness welds, automatic welding in CO2 or under welding
flux
Plug and slot welds- subject to shear 1.5 ... 2* higher values -
welds with vertical walls, manual arc welding
* lower values - welds with sloped walls, welding in CO2 or
under welding flux
Spot resistance welds- subject to shear 1.5- subject to tear
2
1.1 ... 1.3
- very accurate input information - perfect knowledge of
material characteristics - high quality and exact observance of
production technology - high-quality welds without internal
tensions - welding is performed only by very experienced, certified
welders - weld quality guaranteed by a detailed output control
(radioscopy, magnetic tests, ultrasonic, ..) - insignificant
connections without serious impacts in case of damage
1.3 ... 1.6
- less accurate calculation without experimental verification -
lower accuracy in production technology - standard-quality welds -
welding performed by qualified welders - welds with a standard
output control - less important connections
1.6 ... 2.0
- reduced accuracy of calculations - approximate specification
of material characteristics - inaccurate knowledge of actual action
of external load - welds with increased risk of existence of
internal tensions - welds with unguaranteed quality - very
important connections with danger to life or high material losses
in case of damage
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Hint 1: A detailed description of the calculation for rated
stresses for various types of welded connections can be found in
the theoretical part of the Help.
Hint 2: This method is suitable for experienced users who are
able to perform a sound design of the required safety degree
depending on the specific type, workmanship and load of the welded
joint.
1.5 Method of conversion coefficients. This method expands the
basic calculation method and brings certain simplification to the
area of considering the designed joint load-bearing capacity. As in
the previous method, the respective theoretical rated stresses in
the load-bearing weld section are calculated first. In the next
step, the resulting comparative stress is defined based on these
rated stresses using the predefined empirically set conversion
coefficients. These coefficients consider the anisotropic
properties of weld material in the direction of the acting stresses
and their size will therefore depend on the type, workmanship and
the way of load of the welded joint.
The strength checks of the weld are then performed by comparison
of the calculated comparative stress to the yield strength of the
basic material. The required safety against the yields point "FSy"
will consider only the qualitative parameters of the welded
connection for this method. With respect to the accuracy and value
of input information, connection importance, production quality,
operating conditions and calculation accuracy, it is usually chosen
from 1.1 to 2.
nformation values for the choice of safety coefficient FSy:
Note: For connections operating in a corrosive environment or at
high temperatures, higher values for safety coefficient FSy are
also used.
Hint 1: The values of the predefined conversion coefficient may
be adjusted in paragraph [3.1] on the sheet "Options".
Hint 2: This method is especially suitable for less experienced
users. Its use may be advantageous in case of a comparative
calculation when several designed solutions with a different type
of weld need to be compared.
1.7 Method of permissible stresses. The most complicated task in
the strength checks of welded connections usually applies to
defining the correct value of the permissible weld stress. The
logical result is therefore the fact that it is this area of
specifying the permissible stresses where the most noticeable
differences between various recommended procedures used in
technical practice appear.
The previous calculation methods control the load-bearing
capacity of the joint by simple comparison of calculated stresses
to the yield strength of the basic material. They do not provide
for direct handling of the requirement of strength checks for the
known values of permissible weld stress prescribed by the standards
or company procedures. This method therefore obliges users who want
to use this program to design the joint and at the same time comply
with the prescribed procedures for the strength checks.
Unlike the previous method, this method uses the comparison of
calculated stresses to the value of permissible stress "SwA"
defined directly by the user for strength checks. As the required
safety level is usually already included in the value of the
prescribed permissible stress, the applied safety degree "FS" is
used as an auxiliary quantity and only describes a certain degree
of "over-dimensioning" of the designed connection. The safety value
"FS" will then depend on the procedure applied by the user in order
to define the permissible stress, and it is usually FS1. Hint 1:
Some values of permissible stresses that are specified in
professional literature are derived for a different methodology of
comparative stresses calculation. That is why this method enables
variable behaviour of the calculation. Set the basic parameters for
the calculation of comparative stresses in paragraph [3.10] on the
sheet "Options".
Hint 2: Use this method if you need to check the load-bearing
capacity of the welded connection for known (rated) permissible
connection stress.
1.9 Material of the connected parts. This paragraph is used for
the selection of suitable material for the connected parts.
The list on line [1.10] is used for selection of the required
material standard. Choose the material for the connected parts
proper from the list [1.11]. The first five rows of the list is
reserved for materials defined by the user. Information and
settings of proper materials can be found in the document "Workbook
(calculation) modifications". Other rows of the list include a
selection of materials for the actually specified standard
[1.10].
Note: In case the checkbox to the right of the selection list is
enabled, the necessary parameters for the chosen material are
determined automatically. Otherwise, fill in the material
characteristics manually.
1.10 Material standard. Select the required national standard
from the list to determine the joint material.
Recommendation: Most European countries are currently
substituting or have already substituted the local material
standards (DIN, BS, UNI, UNE, ...) with corresponding equivalents
of standards EN. Therefore we recommend using only the appropriate
European norms EN.
Butt welds. [2] This paragraph is intended for the geometrical
design and strength checks of connections with butt welds.
Butt welds originate in the joint gap of connected parts and are
usually used as load-bearing, force welds. In order to achieve
perfect workmanship of the welds, it is usually necessary to
perform modification of the contact surfaces of the connected
parts. The method of welded surface treatment is set by the
workmanship of the connection, the thickness of the welded parts,
the welding method and the accessibility of the welded spot.
Warning: This program is designed for the calculation of
connections with uniform, fully penetrated butt welds. The
recommended procedures for handling special cases of connections
(partly penetrated welds, intermittent welds, combined welds) can
be found in the theoretical part of the Help.
Designing procedure for the connection:
1. On line [2.1] choose the required connection type. 2. In
paragraph [2.2] set all required connection dimensions. 3. On line
[2.6] select whether the connection is to be controlled only for
the effective weld length. 4. Check the appropriate check boxes in
paragraph [2.7] to set the respective load combination. Specify the
values of selected loads. 5. If "Method of permissible stresses"
(see. [1.7]) is used, set the permissible stress value on line
[2.15]. 6. Check the calculated safety of the designed connection
on line [2.17]. 7. If you want to optimize the connection
dimensions or the designed connection does not comply with the
strength checks, use the "min" buttons in paragraph [2.2] to find
the suitable
1.1 ... 1.3
- very accurate input information - perfect knowledge of
material characteristics - high quality and exact observance of
production technology - high-quality welds without internal
tensions - welding is performed only by very experienced, certified
welders - weld quality guaranteed by a detailed output control
(radioscopy, magnetic tests, ultrasonic, ..) - insignificant
connections without serious impacts in case of damage
1.3 ... 1.6
- less accurate calculation without experimental verification -
lower accuracy in production technology - standard-quality welds -
welding performed by qualified welders - welds with a standard
output control - less important connections
1.6 ... 2.0
- reduced accuracy of calculations - approximate specification
of material characteristics - inaccurate knowledge of actual action
of external load - welds with increased risk of existence of
internal tensions - welds with unguaranteed quality - very
important connections with danger to life or high material losses
in case of damage
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connection dimensions. 8. If you want to establish the maximum
admissible load for the respective connection, use the "max" button
in paragraph [2.7].
Hint: Detailed information on the butt weld calculation can be
found in the theoretical part of the Help.
2.1 Connection type. Check the switch with the respective image
to select the required connection type.
2.2 Dimensions of the connection. Use this paragraph to set all
required connection dimensions.
Hint: After any of the "min" buttons located to the right of the
input fields are pressed, the program will find the minimum
suitable value of the respective dimension for the respective load,
selected material and required connection safety.
2.6 Effective weld length. In a normal type of weld, so-called
"end down-slopes" are formed. They result in weakening of the
section at the weld's beginning and end. The effective weld length
will then be smaller than the actual length (reduced by a
worse-quality weld beginning and end). For more accurate
calculations, we therefore recommend controlling the load-bearing
capacity of welds only for that part (length) of the weld that has
a rated section.
Check this switch in order to consider only the effective weld
length during the strength checks of the connection. The program
will set the effective length automatically from the specified
dimensions. If the check box is unchecked, the load-bearing
capacity of the weld will be calculated directly for the dimensions
of the connection set in paragraph [2.2].
Recommendation: The calculations using the effective length for
the weld control err to the side of safety. Therefore, the switch
should preferably be on constantly. Exceptions include cases when
the weld is provided with special treatment (see the figure) or if
it is impossible to use the automatic calculation for the effective
length setting (e.g. for intermittent welds).
Note: This parameter is insignificant for connections with
circumferential welds.
2.7 Loading of the connection. Check the appropriate check boxes
to the left of this paragraph to set the respective weld load
combination. Specify the size for the selected loads.
Note: For some types of connection [2.1], the program enables
the calculation using only one type of loading.
Hint: If you want to establish the maximum permissible load for
the respective connection, use the "max" button located to the
right of the respective input field.
2.13 Strength checks of the connection. If "Basic calculation
method" or "Method of conversion coefficients" (see [1.3] or [1.5])
is used, the strength checks of the connection are performed by
comparison of the calculated theoretical stress in the weld [2.16]
to the yield strength of the selected material of the connection
[2.14]. If the connection is to conform, the resulting safety
against yield point [2.17] must be higher than the safety required
([1.4] or [1.6]).
If "Method of permissible stresses" (see [1.7]) is used for
calculation, the strength checks of the connection will be
performed by comparison of the calculated theoretical stress [2.16]
to the permissible stress [2.15]. If the connection is to conform,
the resulting safety rate [2.17] must be higher than the safety
required [1.8].
Hint 1: You can find the minimum safety values in the respective
notes for paragraph [1.2] or in the theoretical part of the
Help.
Hint 2: If the designed connection does not conform to the
strength checks, you can use the respective "min" button in
paragraph [2.2] to find the suitable connection dimension.
2.15 Permissible stress. If "Method of permissible stresses"
(see. [1.7]) is used for the calculation, set the value for the
permissible stress of the connection material on this line. This
value is then used for defining the safety rate [2.17] of the
designed connection.
Note: For the remaining two calculation methods (see [1.3],
[1.5]), this line is only informative and the value of the
permissible stress is set automatically based on the required
safety and the yield strength of the selected material.
Fillet welds loaded in the connection plane (Lap joints). [3]
Fillet welds are located along the wedge-shaped edge of connected
parts and their basic cross-section includes an isosceles
rectangular triangle. They are usually used for load-bearing, force
welds in T-shape connections, cross-butt connections, angle
connections and for lap joints. The welded parts do not need shape
adjustment. For statically loaded connections, usually a flat weld
is used, while a concave weld is more appropriate for dynamically
loaded connections, as it has lower notch effects.
This part of the calculation is used for the geometrical design
and strength checks of fillet weld connections loaded in the
connection plane. Typical examples of such connections include lap
joints and double-sided connections of short rigid beams.
Warning: This program is designed for the calculation of welds
with uniform fillet welds. The recommended methods of handling
connections with intermittent welds or with combined welds can be
found in the theoretical part of the Help.
Designing procedure for the connection:
1. 1. On line [3.1] choose the required connection type (form of
weld group). 2. In paragraph [3.2] set all required connection
dimensions. 3. In paragraph [3.11] set the respective parameters
for the connection and calculation. 4. Check the appropriate check
boxes in paragraph [3.15] to set the respective load combination.
Specify the values of selected loads. 5. If "Method of permissible
stresses" (see. [1.7]) is used, set the permissible stress value on
line [3.26]. 6. Check the calculated safety of the designed
connection on line [3.31]. 7. If you want to optimize the
connection dimensions or the designed connection does not comply
with the strength checks, use the "min" buttons in paragraph [3.2]
to find the suitable
connection dimensions. 8. If you want to establish the maximum
admissible load for the respective connection, use the "max" button
in paragraph [3.15].
Hint: Detailed information on the fillet weld calculation can be
found in the theoretical part of the Help.
3.1 Form of weld group. Use a switch with the respective picture
to choose the required type of connection (form of weld group).
Note: The switches marked with a blue weld in the picture
(connections no. 17, 18 and 36) are used for the calculation of
connections without closer details regarding the form of weld
group. For a connection with a form of weld group that is not axial
symmetric (connection no. 18) we recommend performing the check of
stress in the respective weld area (the most distant from the
centre of gravity) gradually in all four quadrants.
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3.2 Dimensions of the connection. Use this paragraph to set all
required connection dimensions.
Hint 1: You can find the recommended procedures to choose the
appropriate weld dimensions in the theoretical part of the
Help.
Hint 2: After any of the "min" buttons located to the right of
the input fields are pressed, the program will find the minimum
suitable value of the respective dimension for the respective load,
selected material and required connection safety.
3.3 Weld throat thickness. The fillet weld throat thickness is
defined as the height of the biggest isosceles triangle inscribed
into a weld section without penetration.
Hint: The minimum fillet weld thickness is usually chosen
depending on the used material and the thickness of the welded
parts. You can find the recommended procedures to choose the
appropriate weld thickness in the theoretical part of the Help.
3.8 Standard profiles. This paragraph is used to enable the
setting (automatic completion) of the respective dimensions of the
connection [3.2] for connections with welded on beams with
standardized profiles.
When choosing the profile, proceed as follows:
1. Choose the required profile type (standard) from the
drop-down menu [3.9]. 2. Choose the respective profile dimension
from list [3.10]. 3. Press the "
-
defining the safety rate [3.31] of the designed connection.
Note: For the remaining two calculation methods (see [1.3],
[1.5]), this line is only informative and the value of the
permissible stress is set automatically based on the required
safety and the yield strength of the selected material.
Fillet welds loaded in the plane perpendicular to the connection
plane (T-joints). [4] Fillet welds are located along the
wedge-shaped edge of connected parts and their basic cross-section
includes an isosceles rectangular triangle. They are usually used
for load-bearing, force welds in T-shape connections, cross-butt
connections, angle connections and for lap joints. The welded parts
do not need shape adjustment. For statically loaded connections,
usually a flat weld is used, while a concave weld is more
appropriate for dynamically loaded connections, as it has lower
notch effects.
This part of the calculation is used for the geometrical design
and strength checks of fillet weld connections loaded in the plane
perpendicular to the connection plane. A typical example of such
connections is the connection of beams to the base plate
(T-connection).
Warning: This program is designed for the calculation of welds
with uniform fillet welds. The recommended methods of handling
connections with intermittent welds or with combined welds can be
found in the theoretical part of the Help.
Designing procedure for the connection:
1. 1. On line [4.1] choose the required connection type (form of
weld group). 2. In paragraph [4.2] set all required connection
dimensions. 3. In paragraph [4.11] set the respective parameters
for the connection and calculation. 4. Check the appropriate check
boxes in paragraph [4.14] to set the respective load combination.
Specify the values of selected loads. 5. If "Method of permissible
stresses" (see. [1.7]) is used, set the permissible stress value on
line [4.26]. 6. Check the calculated safety of the designed
connection on line [4.29]. 7. If you want to optimize the
connection dimensions or the designed connection does not comply
with the strength checks, use the "min" buttons in paragraph [4.2]
to find the suitable
connection dimensions. 8. If you want to establish the maximum
admissible load for the respective connection, use the "max" button
in paragraph [4.14].
Hint: Detailed information on the fillet weld calculation can be
found in the theoretical part of the Help.
4.1 Form of weld group. Use a switch with the respective picture
to choose the required type of connection (form of weld group).
Note: The switches marked with a blue weld in the picture
(connections no. 25 and 26) are used for the calculation of
connections without closer details regarding the form of weld
group.
4.2 Dimensions of the connection. Use this paragraph to set all
required connection dimensions.
Hint 1: You can find the recommended procedures to choose the
appropriate weld dimensions in the theoretical part of the
Help.
Hint 2: After any of the "min" buttons located to the right of
the input fields are pressed, the program will find the minimum
suitable value of the respective dimension for the respective load,
selected material and required connection safety.
4.3 Weld throat thickness. The fillet weld throat thickness is
defined as the height of the biggest isosceles triangle inscribed
into a weld section without penetration.
Hint: The minimum fillet weld thickness is usually chosen
depending on the used material and the thickness of the welded
parts. You can find the recommended procedures to choose the
appropriate weld thickness in the theoretical part of the Help.
4.8 Standard profiles. This paragraph is used to enable the
setting (automatic completion) of the respective dimensions of the
connection [4.2] for connections with welded on beams with
standardized profiles.
When choosing the profile, proceed as follows:
1. Choose the required profile type (standard) from the
drop-down menu [4.9]. 2. Choose the respective profile dimension
from list [4.10]. 3. Press the "
-
As is obvious from the picture, the stress in the upper weld
acts in the direction of the tear of the beam and has the character
of tensile stress. The stress in the lower weld will then have the
character of compression stress. In the welds symmetrical along the
neutral axis, the value of both stresses will be the same; in the
asymmetrical welds, the values of compression stress may be higher.
In view of the load-bearing capacity of the welded connection,
however, the tensile stress is usually more important for beams
connected in that way.
In normal calculation, the program assesses the maximum
calculated stress regardless of its direction during the strength
checks. By checking this switch, you will suppress the check of
compression (negative) stresses. During the strength checks, the
program will assess only the tensile (positive) stress.
Note: This parameter is insignificant for welds symmetrical
along the neutral axis.
4.14 Loading of the connection. Check the appropriate check
boxes to the left of this paragraph to set the respective weld load
combination. Specify the size for the selected loads.
Hint: If you want to establish the maximum permissible load for
the respective connection, use the "max" button located to the
right of the respective input field.
4.24 Strength checks of the connection. If "Basic calculation
method" or "Method of conversion coefficients" (see [1.3] or [1.5])
is used, the strength checks of the connection are performed by
comparison of the maximum calculated theoretical stresses [4.27,
4.28] to the yield strength of the selected material of the
connection [4.25]. If the connection is to conform, the resulting
safety against yield point [4.29] must be higher than the safety
required ([1.4] or [1.6]).
If "Method of permissible stresses" (see [1.7]) is used for
calculation, the strength checks of the connection will be
performed by comparison of the maximum calculated theoretical
stresses [4.27, 4.28] to the permissible stress [4.26]. If the
connection is to conform, the resulting safety rate [4.29] must be
higher than the safety required [1.8].
Hint 1: You can find the minimum safety values in the respective
notes for paragraph [1.2] or in the theoretical part of the
Help.
Hint 2: If the designed connection does not conform to the
strength checks, you can use the respective "min" button in
paragraph [4.2] to find the suitable connection dimension.
4.26 Permissible stress. If "Method of permissible stresses"
(see. [1.7]) is used for the calculation, set the value for the
permissible stress of the connection material on this line. This
value is then used for defining the safety rate [4.29] of the
designed connection.
Note: For the remaining two calculation methods (see [1.3],
[1.5]), this line is only informative and the value of the
permissible stress is set automatically based on the required
safety and the yield strength of the selected material.
Plug and slot welds. [5] This paragraph is intended for the
geometrical design and strength checks of connections with plug and
slot welds.
Plug and slot welds are usually used for lap joints. They are
not suitable for the transfer of high forces and are especially not
suitable for dynamically loaded connections. The connection is
formed by the weld on walls of circular or oval openings and in the
contact surface of the adjoining part. Plugs and slots of small
dimensions are usually fully filled with the weld.
These welds are not suitable for the joining of thicker plates
and are usually used for thinner plates up to approx. 15 mm thick.
In view of the stress, slot welds are more preferable due to the
better quality of penetration of the weld root. A better quality of
the weld, i.e. better strength characteristic of the joint, can be
achieved by sloped walls of openings.
Designing procedure for the connection:
1. On line [5.1] choose the required connection type. 2. In
paragraph [5.2] set all required connection dimensions. 3. Set the
appropriate value for the connection loading on line [5.8]. 4. If
"Method of permissible stresses" (see. [1.7]) is used, set the
permissible stress value on line [5.11]. 5. Check the calculated
safety of the designed connection on line [5.14]. 6. If you want to
optimize the connection dimensions or the designed connection does
not comply with the strength checks, use the "min" buttons in
paragraph [5.2] to find the suitable
connection dimensions. 7. If you want to establish the maximum
admissible load for the respective connection, use the "max" button
on line [5.8].
Hint: Detailed information on the plug weld calculation can be
found in the theoretical part of the Help.
5.1 Connection type. Choose the required type of connection from
the drop-down menu.
5.2 Dimensions of the connection. Use this paragraph to set all
required connection dimensions.
Hint 1: You can find the recommended procedures to choose the
appropriate weld dimensions in the theoretical part of the
Help.
Hint 2: After any of the "min" buttons located to the right of
the input fields are pressed, the program will find the minimum
suitable value of the respective dimension for the respective load,
selected material and required connection safety.
5.7 Loading of the connection. Set the appropriate value for the
connection loading on line [5.8].
Hint: If you want to establish the maximum permissible load for
the respective connection, use the "max" button located to the
right of the input field.
5.9 Strength checks of the connection. If "Basic calculation
method" or "Method of conversion coefficients" (see [1.3] or [1.5])
is used, the strength checks of the connection are performed by
comparison of the maximum calculated theoretical stresses [5.12,
5.13] to the yield strength of the selected material of the
connection [5.10]. If the connection is to conform, the resulting
safety against yield point [5.14] must be higher than the safety
required ([1.4] or [1.6]).
If "Method of permissible stresses" (see [1.7]) is used for
calculation, the strength checks of the connection will be
performed by comparison of the maximum calculated theoretical
stresses [5.12, 5.13] to the permissible stress [5.11]. If the
connection is to conform, the resulting safety rate [5.14] must be
higher than the safety required [1.8].
Hint 1: You can find the minimum safety values in the respective
notes for paragraph [1.2] or in the theoretical part of the
Help.
Hint 2: If the designed connection does not conform to the
strength checks, you can use the respective "min" button in
paragraph [5.2] to find the suitable connection dimension.
5.11 Permissible stress. If "Method of permissible stresses"
(see. [1.7]) is used for the calculation, set the value for the
permissible stress of the connection material on this line. This
value is then used for defining the safety rate [5.14] of the
designed connection.
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Note: For the remaining two calculation methods (see [1.3],
[1.5]), this line is only informative and the value of the
permissible stress is set automatically based on the required
safety and the yield strength of the selected material.
Spot (resistance) welds. [6] This paragraph is intended for the
geometrical design and strength checks of connections with spot
welds.
Spot resistance welds are usually used to connect thin plates
and thin-walled parts. They are especially very useful in lot
production. The connections with spot welds are not very
appropriate for transferring high forces. In view of the type of
stress, we distinguish two basic types of connections with spot
welds: - connections with welds stressed in shear (lap joints) -
connections with welds stressed in tear (by tension)
In technical practice, not more than 3 parts with maximum total
thickness up to approx. 15 mm are allowed to be joined for
connections with resistance welds. The thickness ratio for
individual parts should not exceed 1:3. The welds should be
positioned towards the external force so that they are always only
stressed in shear. Spot welds stressed in tension have
significantly lower load-bearing capacity, which is why their use
is not recommended. Lap welds can be made as single-shear or
double-shear. A minimum of 2 and maximum of 5 spot connections
should be located in the direction of acting force.
Designing procedure for the connection:
1. On line [6.1] choose the required connection type. 2. In
paragraph [6.2] set all required connection dimensions. 3. Set the
appropriate value for the connection loading on line [6.7]. 4. If
"Method of permissible stresses" (see. [1.7]) is used, set the
permissible stress value on line [6.10]. 5. Check the calculated
safety of the designed connection on line [6.13]. 6. If you want to
optimize the connection dimensions or the designed connection does
not comply with the strength checks, use the "min" buttons in
paragraph [6.2] to find the suitable
connection dimensions. 7. If you want to establish the maximum
admissible load for the respective connection, use the "max" button
on line [6.7].
Hint: Detailed information on the spot weld calculation can be
found in the theoretical part of the Help.
6.1 Connection type. Check the switch with the respective image
to select the required connection type.
6.2 Dimensions of the connection. Use this paragraph to set all
required connection dimensions.
Hint 1: You can find the recommended procedures to choose the
appropriate weld dimensions in the theoretical part of the
Help.
Hint 2: After any of the "min" buttons located to the right of
the input fields are pressed, the program will find the minimum
suitable value of the respective dimension for the respective load,
selected material and required connection safety.
6.6 Loading of the connection. Set the appropriate value for the
connection loading on line [6.7].
Hint: If you want to establish the maximum permissible load for
the respective connection, use the "max" button located to the
right of the input field.
6.8 Strength checks of the connection. If "Basic calculation
method" or "Method of conversion coefficients" (see [1.3] or [1.5])
is used, the strength checks of the connection are performed by
comparison of the maximum calculated theoretical stresses [6.11,
6.12] to the yield strength of the selected material of the
connection [6.9]. If the connection is to conform, the resulting
safety against yield point [6.13] must be higher than the safety
required ([1.4] or [1.6]).
If "Method of permissible stresses" (see [1.7]) is used for
calculation, the strength checks of the connection will be
performed by comparison of the maximum calculated theoretical
stresses [6.11, 6.12] to the permissible stress [6.10]. If the
connection is to conform, the resulting safety rate [6.13] must be
higher than the safety required [1.8].
Hint 1: You can find the minimum safety values in the respective
notes for paragraph [1.2] or in the theoretical part of the
Help.
Hint 2: If the designed connection does not conform to the
strength checks, you can use the respective "min" button in
paragraph [6.2] to find the suitable connection dimension.
6.10 Permissible stress. If "Method of permissible stresses"
(see. [1.7]) is used for the calculation, set the value for the
permissible stress of the connection material on this line. This
value is then used for defining the safety rate [6.13] of the
designed connection.
Note: For the remaining two calculation methods (see [1.3],
[1.5]), this line is only informative and the value of the
permissible stress is set automatically based on the required
safety and the yield strength of the selected material.
Setting calculations, change the language. Information on
setting of calculation parameters and setting of the language can
be found in the document "Setting calculations, change the
language".
Supplements - This calculation: 3.0 User setting of calculation
parameters. Depending on the applied calculation method (see the
main calculation [1.2]) you can use this part to set some
parameters affecting the calculation of the welded connections
proper. In paragraph [3.1] you can set the required value of the
coefficients used for "Method of conversion coefficients".
Paragraph [3.10] is used to set the basic calculation parameters
for "Method of permissible stresses".
Hint: Detailed information on the used calculation methods can
be found in the theoretical part of the Help.
3.2 Setting the weld anisotropic coefficients. Use this
paragraph to set the values of conversion coefficients used by the
program in the calculation of comparative stresses for "Method of
conversion coefficients".
Recommended values of conversion coefficients: Weld type, way of
load CoefficientButt welds subject to compression 1.00Butt welds
subject to tension
- manual arc or flame welding - contact resistance welding -
manual welding, connections after slotting with rewelded root -
automatic welding under welding flux or in CO2 , double-sided
welded connections - electroslag welding
0.85 ... 1.00
Butt welds subject to shear 0.70End fillet welds
- manual welding, weld without penetration - manual arc welding,
electrodes with higher strength (min. 20% more) - automatic welding
under welding flux or in CO2 , weld thickness > 8mm, penetration
depth 0.2a
0.75 ... 1.00
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3.11 Method of comparative stress calculation for butt welds.
Use the appropriate switch to select the required relation that
will be further used in the calculation of comparative stress.
For butt-welded connections, technical calculations most
frequently use the second relation,
which is also applied by the program in "Basic calculation
method". If this relation is used, the permissible tensile stress
of the basic material is usually used to define the permissible
stress in the weld section.
The first relation
is used to define the rated stresses in a butt weld section less
frequently. This method is used e.g. in DIN 18800, or for a
simplified calculation method according to prEN 1993-1-8.
Generally, we can say that if used, the value of the permissible
stress should be derived based on the permissible stress of the
material in shear.
3.12 Method of comparative stress calculation for fillet welds.
Use the appropriate switch to select the required relation that
will be further used in the calculation of comparative stress.
For fillet-welded connections, the technical calculations almost
solely use the first relation,
which is also applied by the program in "Basic calculation
method". When this relation is used, the permissible stress in
shear of the basic material is usually used to define the
permissible stress in the weld section.
With respect to the established calculation convention (for the
sake of the calculation, the load-bearing weld section is reclined
into the plane of connecting the parts), the literature mentions
the second relation for fillet welds only very rarely.
If you still use it, the value of the permissible stress should
be derived based on the permissible tension stress of the
material.
3.13 Calculation with distribution of shear stress. In some
technical calculations, the theory of shear stress distribution is
used for strength checks of fillet welds subject to shear force in
the plane of connection of parts. According to this theory, the
shear stresses in the loaded section are transferred only by the
welds parallel to the stress direction. When checking this switch,
the program will use the reduced load-bearing section of the weld
group in calculation of shear stresses.
Recommendation: This switch should not be used for cases when
the total length of the welds perpendicular to the stress direction
is significantly greater than the total length of the welds
parallel to the weld direction. For such welded connections, the
calculation will produce misleading results if the switch is
on.
Note: This switch has no meaning for connections with welds
located in only one direction.
Workbook modifications (calculation). General information on how
to modify and extend calculation workbooks is mentioned in the
document "Workbook (calculation) modifications".
- automatic welding under welding flux, single-layer welds less
than 8mm thick, penetration depth 0.4a Side fillet welds
- manual welding, weld without penetration - manual arc welding,
electrodes with higher strength (min. 20% more) - automatic welding
under welding flux or in CO2 , weld thickness > 8mm, penetration
depth 0.2a - automatic welding under welding flux, single-layer
welds less than 8mm thick, penetration depth 0.4a
0.65 ... 0.90
Plug and slot welds - manual arc welding, welds with vertical
walls - welding under welding flux or in CO2 , welds with sloped
walls
0.50 ... 0.65
Spot resistance welds subject to shear 0.65Spot resistance welds
subject to tension 0.50
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