-
ABBREVIATIONSA - Areabf - Effective width of flangeD - Overall
depth of beam or slab or diameter of column;
dimension of a rectangular column in the direction
underconsideration
Df - Thickness of flangeDL - Dead loadd - Effective depth of
beam or slabd - Depth of compression reinforcement from the
highly
compressed faceEC - Modulus of elasticity of concreteEL -
Earthquake loadEs - Modulus of elasticity of steelfck -
characteristic cube compressive strength of concretefy -
Characteristic strength of steelIef - Effective moment of inertiaK
- Stiffness of memberk - Constant or coefficient or factorLd -
Development lengthLL - Live load or imposed loadLw - Horizontal
distance between centers of lateral restraintl - Length of a column
or beam between adequate lateral
restraints or the unsupported length of a columnlef - Effective
span of beam or slab or effective length of columnlex - Effective
length about x-x axisley - Effective length about y-y axisln -
Clear span, face-to-face of supportslx - Length of shorter side of
slably - Length of longer side of slabll - Span in the direction in
which moments are determined, centre
to centre of supportsl2 - Span transverse to I,, centre to
centre of supportsl2 - l2 for the shorter of the continuous spansM
- Bending momentm - Modular ratioP - Axial load on a compression
memberq0 - Calculated maximum bearing pressure of soilr - Radiuss -
Spacing of stirrups or standard deviationT - Torsional momentV -
Shear forceW - Total load
-
X - Depth of neutral axisZ - Modulus of sectionz - Lever armf -
Partial safety factor for loadm - Partial safety factor for
materialm - Percentage reduction in moment
- Creep strain of concretecbc - Permissible stress in concrete
in bending compressioncc - Permissible stress in concrete in direct
compressionsc - Permissible stress in steel in compressionst -
Permissible stress in steel in tensionsv - Permissible tensile
stress in shear reinforcementc - Shear stress in concretec,max -
Maximum shear stress in concrete with shear reinforcementv -
Nominal shear stress - Diameter of bar
`
-
INTRODUCTION
GENERAL PRINCIPLES OF DESIGN
OBJECTIVES OF STRUCTURAL DESIGNS
The design of a structure must satisfy three basic
requirements:
Stability: - To prevent overturning, sliding or buckling of the
structure, or part of it,under the action of loads.
Strength: - To resist safely the stresses induced by the loads
in the various structuralmembers.
Serviceability: - To ensure satisfactory performance under
service load conditionswhich implies providing adequate stiffness
and reinforcement to contain deflections,crack widths and
vibrations within acceptable limits, and also
providingimpermeability and durability.
STRUCTURAL SYSTEM
The whole structure is analyzed as closed column beam frame in
ETABS analysissoftware and the design of various structural
elements done manually.
Isolated Column foundations are proposed by the Geotechnical
Expert and thefoundations and building is designed for GF+6 floors.
As per the soil report, soil conditionat some portion is very loose
as per the bore log. First two boreholes terminated at veryshallow
depth of 3 to 4m where hard strata are available. The fourth
borehole at south eastcorner of the plot is having very loose soil
profile of N value 10 at upper level and the hardstrata obtained at
9m from GL and at this portion the foundation is proposed with
pilefoundation. This borehole may be a typical case, so it is
recommend to inspect this area bythe EIC and the hard strata is
found at reasonable depth, the pile foundation can be replaceswith
Isolated spread foundation which will effectively reduce the cost
of foundation.
Design parameters
Design loads
Dead loadsThe dead loads are in accordance with IS 875 Part 1
(1987).
For the calculation of dead load acting over beams at various
levels the unit weight ofthe building materials are taken according
to that given in IS 875 Part -I-Dead weight ofbuilding materials.
For calculating the live load acting over various floor levels IS
875 Part IIis referred. All the loads are given according to the
data given in the floor plans and crosssections given. The self
weight of the structure is taken by the software itself.
The unit weight of hollow brick masonry is taken as =20
kN/m3
The unit weight of concrete is taken as =25 kN/m3
-
Weight of brick wall = 0.20 x 3.4x 20 = 13.60kN/m
Wt of floor finish = 1.0 kN/m2
Self Wt of floor slab (12cm Thick) = 3 kN/m2
Load considered for water tank = 15 kN/m2
Live loadsThe live loads are in accordance with IS 875 Part 2
(1987).
type Live load (kN/m2)Operation theatres,
ICUs, 3
Offices, Lounges, 3Stair cases, Storages,
X rays, Balconies,Corridors,
4
Wards, Rooms,Toilets,
Consultations,2
Earthquake Loads as per IS: 1893 (part 1): 2002Dynamic forces on
multi-storied are best computed through a detailed vibration
analysis.Detailed dynamic analysis or modal analysis or pseudo
static analysis should be carried outdepending on the importance of
problem. BIS Code 1893 (Part 1): 2002 recommends that[Ref: Cl:
7:8:1]
Dynamic analysis shall be performed to obtain the design seismic
force, and its distribution todifferent levels along the height of
the building and to the various lateral load-resistingelements for
the following buildings:
a) Regular buildings those greater than 40m in height in Zone IV
andZone V, and those greater than 90m in height in Zone II and Zone
III.
b) Irregular building all framed buildings higher than 12m in
Zones IVand Zone V, and those greater than 40m in height in Zone II
and III.
Since the height of the residential complex is 44.35m and its
located in Zone III, staticmethod of analysis was performed to find
the seismic load and its distribution.
Static method:
The base shear or total design lateral force along any principal
direction shall bedetermined by the following expression:
VB = Ah W
-
Where,
VB = the design base shear
Ah = Design horizontal acceleration spectrum value using the
fundamental naturalperiod T.
W = Seismic weight of the building.
The design horizontal seismic coefficientgR2
SIZ ah A
Where,
Z = Zone factor given in table 2, for the Maximum Considered
Earthquake (MCE)and service life of structure in a zone. The factor
2 in the denominator of Z isused so as to reduce the MCE zone
factor to the factor for Design BasisEarthquake (DBE)
I = Importance factor, depending upon the functional use of
structures, characterizedby hazardous consequences of failure,
post-earthquake functional needs,historical value or economic
importance (Table 6 IS 1893 (Part 1):2002
R = Response reduction factor, depending on the perceived
seismic damageperformance of the structure, characterized by
ductile or brittle deformations.However, the ratio (I/R) shall not
be greater than 1.0. The values for buildingsare given in Table 7
of IS 1893 (Part 1): 2002.
gSa Average response acceleration coefficient.
Distribution of Design Force
The design base shear VB was distributed along the height of the
buildings asper the following expressions.
ni
iii
iii
hW
hWVBQ
1
2
2
Where,
iQ = Design lateral force at floor i
iW = Seismic weight of floor i
ih = Height of floor i measured from base.
-
n = Number of storeys in the building is the number of levels at
which the masses arelocated.
Seismic weight, W
The seismic weight of each floor is its full dead load plus
appropriate amountof imposed loads while computing the seismic
weight of each floor, the weight of columnsand walls in any storey
shall be equally distributed to the floors above and below the
storey.The seismic weight of the whole building is the sum of the
seismic weights of all the floors.Any weight supported in between
storey shall be distributed to the floors above and below ininverse
proportion to its distance from the floors.
Imposed uniformly distributed floorloads kN/m
Percentage of imposed load
%
Upto and including 3.0 25
Above 3.0 50
Table-Percentage of imposed load to be considered in seismic
weight calculation
Determination of Design Base Shear for Seismic Analysis:
As per IS 1893 (Part 1):2002
Fundamental natural period, Ta (Clause 7.6.2) = 0.075h0.75
h = height of building exclude basement floor = 20.16m
Ta = 0.8
For 0.4
-
IS1893 2002 Auto Seismic Load CalculationThis calculation
presents the automatically generated lateral seismic loads for load
pattern EQX according toIS1893 2002, as calculated by ETABS.
Direction and Eccentricity
Direction = Multiple
Eccentricity Ratio = 5% for all diaphragms
Structural Period
Period Calculation Method = User Specified
User Period T = 0.8 sec
Factors and Coefficients
Seismic Zone Factor, Z [IS Table 2] Z = 0.16
Response Reduction Factor, R [IS Table 7] R = 3
Importance Factor, I [IS Table 6] I = 1.5
Site Type [IS Table 1] = II
Seismic Response
Spectral Acceleration Coefficient, S a /g [IS6.4.5]
Sag =
1.36T
Sag = 1.36
Equivalent Lateral Forces
Seismic Coefficient, A h [IS 6.4.2] Ah =Z I Sag2 R
Calculated Base Shear
Direction Period Used(sec)W
(kN)V b
(kN)X 0.8 55701.068 3787.6726
X + Ecc. Y 0.8 55701.068 3787.6726
X - Ecc. Y 0.8 55701.068 3787.6726
Applied Story Forces
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Lateral Load to Stories - X
Force, kN
E+30.00 0.15 0.30 0.45 0.60 0.75 0.90 1.05
LFT RF
STAIR RF
ROOF
SXF
FFF
FRF
TF
SF
FF
GFBase
0.7444kN
50.9622kN
139.916kN
278.9351kN
475.6341kN
716.1913kN
1002.4689kN
820.7809kN
259.7531kN
42.2866kN
Story Elevation X-Dir Y-Dir
m kN kNLFT RF 34.6 42.2866 0
STAIRRF 32.1 259.7531 0
ROOF 29.1 820.7809 0
SXF 25.2 1002.4689 0
FFF 21.3 716.1913 0
FRF 17.4 475.6341 0
TF 13.5 278.9351 0
SF 9.6 139.916 0
FF 5.7 50.9622 0
GF 1.5 0.7444 0
Base 0 0 0
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IS1893 2002 Auto Seismic Load CalculationThis calculation
presents the automatically generated lateral seismic loads for load
pattern EQY according toIS1893 2002, as calculated by ETABS.
Direction and Eccentricity
Direction = Multiple
Eccentricity Ratio = 5% for all diaphragms
Structural Period
Period Calculation Method = User Specified
User Period T = 0.8 sec
Factors and Coefficients
Seismic Zone Factor, Z [IS Table 2] Z = 0.16
Response Reduction Factor, R [IS Table 7] R = 3
Importance Factor, I [IS Table 6] I = 1
Site Type [IS Table 1] = II
Seismic Response
Spectral Acceleration Coefficient, S a /g [IS6.4.5]
Sag =
1.36T
Sag = 1.36
Equivalent Lateral Forces
Seismic Coefficient, A h [IS 6.4.2] Ah =Z I Sag2 R
Calculated Base Shear
Direction Period Used(sec)W
(kN)V b
(kN)Y 0.8 55701.068 2525.1151
Y + Ecc. X 0.8 55701.068 2525.1151
Y - Ecc. X 0.8 55701.068 2525.1151
Applied Story Forces
-
Lateral Load to Stories - Y
Force, kN
0 100 200 300 400 500 600 700
LFT RF
STAIR RF
ROOF
SXF
FFF
FRF
TF
SF
FF
GFBase
0.4963kN
33.9748kN
93.2774kN
185.9567kN
317.0894kN
477.4609kN
668.3126kN
547.1873kN
173.1687kN
28.191kN
Story Elevation X-Dir Y-Dir
m kN kNLFT RF 34.6 0 28.191
STAIRRF 32.1 0 173.1687
ROOF 29.1 0 547.1873
SXF 25.2 0 668.3126
FFF 21.3 0 477.4609
FRF 17.4 0 317.0894
TF 13.5 0 185.9567
SF 9.6 0 93.2774
FF 5.7 0 33.9748
GF 1.5 0 0.4963
Base 0 0 0
-
The above parameters are defined in the ETABS software and
software itself will calculatethe seismic loads and create the load
cases and load combinations. The softwareautomatically has done the
distribution of seismic force.
STRUCTURAL MATERIALS
Concrete and Reinforcement
Concrete: M25 for Foundations, M25 for Columns, M25 for Beams,
Slabs, Stairs,and all other components
Steel reinforcement:
Fe500 TMT grade pertaining to IS: 1786 1985
Cover:From durability requirement, environmental exposure
condition is assumed as severe
for substructure and super structure.The nominal cover to
outermost reinforcement shall be as follows for two hour fire
rating.Columns 40mmBeams 25mmSlab 20mmStair 25mm
Foundations 50mm
MODELLING AND ANALYSIS METHODOLOGY
BRIEF:The building is modelled as 3D structure and is analysed
as OMRF (Ordinary
Moment Resisting Frames with Ductile shear walls).The FEM based
structural software (ETABS 2013 Nonlinear) is used for modeling
and analysis of the building.
MODELLINGThe basic approach for using the program is very
straight forward. The user
establishes grid lines, defines material and structural
properties, places structural objectsrelative to the grid lines
using point, line and area object tool. All the types of loads that
thestructure is subjected can be defined and assigned to the
appropriate structural components.The analysis can be performed and
the results are generated in graphical or tabular form thatcan be
printed to a printer or to a file for use in other programs. The
following topics describesome of the important areas in the
modeling.
Defining Material Properties
In the property data area, name of the material, mass per unit
volume, weight per unitvolume, modulus of elasticity, Poissons
ratio should be specified for each type of material
-
defined. The mass per unit volume is used in the calculation of
self-mass of the structure.The weight per unit volume is used in
calculating the self-weight of the structure.
Defining Frame Sections
Frame sections like beams, columns and are defined under this.
The sizes of beamsand columns are fixed here and their
reinforcement requirements and concrete coversdefined. Hinges were
introduced (i.e. end moments were released) near the connecting
whereever required.
Defining Slab Sections
For defining the type of slab section in ETABS, there are three
options availablebased on its behavior, namely shell type, membrane
type and plate type. Shell type behaviormeans, both in-plane
membrane stiffness and out-of-plane plate bending stiffness can
beprovided for the section. Membrane type behavior mean, only
in-plane membrane stiffness isprovided for the section. Plate-type
behavior means that only out-of-plane bending stiffness isprovided
for the section. In the present analysis, slabs are given membrane
type behavior toprovide in plane stiffness and.
Dead load, live load, roof live load, are defined under the
static load case option of thedefine menu. Various load
combinations can also be defined in the load combinationsoption of
the define menu.
Member Property Specifications and Support Condition
The dimensions of different members were fixed based on the
trial design. The columndimensions provided for the modeling is as
prescribed by the Architect. If necessary it willrevised during the
design stage. The beams are provided in such a way that torsion is
releasedsince compatibility torsion alone comes in them. The member
properties assigned are asgiven below.
Slab
Thickness of the slab = 120mm
Beams
The dimensions of the beams are as shown below
Beam Breadth, B Depth, D
Fixed Beams 200mm 500mm
Fixed beam 250mm 600mm
Fixed beam 150mm 600mm
Fixed beam 200mm 750mm
-
Column:
The column dimensions are as follows:
Ground floor: 250mm X 500mm, 300mm X 500mm, 300mm X 600mm,
250mmX 600mm,(steel as per details)
Staircase:
The staircase is provided as an equivalent slab. The thicknesses
of the slab used for staircaseis 175mm
Shear walls
250mm thk shear walls are provided
Support condition
Then support conditions were given to the structure. The support
condition given was Pinned.
LOAD COMBINATION
The following are the load combinations as IS: 456-2000
1) 1.5 D.L + 1.5 LL
2) 1.5 DL + 1.5 SLX
3) 1.5 DL - 1.5 SLX
4) 1.5 DL + 1.5 SLY
5) 1.5 DL - 1.5 SLX
6) 0.9 DL + 1.5 SLX
7) 0.9 DL - 1.5 SLX
8) 0.9 DL + 1.5 SLY
9) 0.9 DL - 1.5 SLY
10) 1.2 DL + 1.2LL + 1.2 SLX
11) 1.2 DL + 1.2LL - 1.2 SLX
12) 1.2 DL + 1.2LL + 1.2 SLY
13) 1.2 DL + 1.2LL - 1.2 SLY
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Modelling Images
Column Layout
-
Completed Model
-
Completed Extruded Model of Buildings
-
DESIGN OF ELEMENTS
Analysis Results
Axial Force on Columns
-
Bending Moment Diagram of Beams
Shear Force Diagram of Beams
-
Design Methodology:
All structural concrete elements will be designed according to
the Limit State Methodas specified in IS: 456 - 2000 for reinforced
concrete elements and detailing will be as perstandards.
Soil Profile
The boreholes numbered 1, 2 and 4 were terminated at 6m, 4.7m,
and 9.3m,respectively from ground level. Hard rock was encountered
in all the boreholes, as theboreholes were terminated at shallow
depth. Lateritic clay and silty sand were found in all thebore
holes. The N value is found to be varying from 03 to greater than
100.
Recommendations
The soil at the site consists of mainly lateritic clay and silty
sand. Hard rock wasfound at all bore holes. The N value is found to
be varying from 10to greater than 100. It issuggested to provide
open foundation which extends to hard rock. The recommendationsmade
in this report are based on the results of the tests as well as
tests done on the samplesrecovered from the boreholes. It is
presumed that the soil below the maximum depth ofexploration at the
site does not vary much or rather improves from that observed at
themaximum depth.
Design of foundation:
This building is proposed to have individual isolated column
footings. Footings aredesigned by taking the forces and moments
from FEM software. The sizes of footings will befixed by making
grouping of loads. The Depth of foundation is decided from four
factors.The depth is initially proposed based on Development length
required according to the size ofbars used. Then that proposed
depth is checked for sufficiency of punching shear (Two wayshear)
and diagonal tension (One way shear), then the depth is checked for
moment. Onfinalizing the satisfying depth for the above conditions
area of steel is worked out for themoment according to the
finalized depth. The safe bearing capacity of the soil is adopted
as400kN/m2 as per the Soil Report (The N value is above 100 at 2m
below GL).At certain portions the foundation system adopted is pile
foundations. The bore hole at southeast corner of the plot shows
that the soil is loose and the hard strata available is at
8.5mbelow GL. At this portion the building id founded in piles. At
the time of execution, detailedexamination of the area can be done
and if the hard strata are available at shallow deoth,
thefoundation can be changed to isolated foundations
The foundations are designed for GF+6 floors.
The reaction of a considered column coming on the foundation is
2400 kN. (DL+LLcombo)
-
DESIGN OF BI-AXIAL ISOLATED RCC FOOTING (IS 456, 2000)Building
Name Hence footing is safe against max gross bearing pr.Footing
Number: f3 tv < tc hence O.K.Node number tv < tc hence
O.K.
tv < allowable hence O.K.COLUMN f3Length (l, dim. || Z axis )
= 500 mmBreadth (b, dim. || X axis) = 500 mm
Breadth 2.7 mFOOTINGFoot length (L, dim. || Z axis) = 2.7 mFoot
Breadth (B, dim. || X axis) = 2.7 mThickness of footing (t) = 800
mmClear cover of footing = 50 mmMain bar dia of footing = 12
mmEffective depth of footing = 744 mm Length 2.7 mSelfweight of the
footing = 145.80 KNArea of Footing(A) = 7.29 m2
Sect mod of foot about Z axis (Zz) = 3.28 m3
Sec mod of foot about X axis (Zx) = 3.28 m3
MATERIALS OF CONSTRUCTIONGrade of concrete fck = 25 N/mm
2
Grade of steel fy = 500 N/mm2
globalZ
globalX
globalX
globalZ
Footing Dimensions
CHECK FOR GROSS BEARING PRESSURESafe NET bearing pressure = 350
KN/m
2
Safe gross bearing pr. = 391.40 KN/m3
(net pr. + depth of foot * soil unit wt)Unfactored load case
number = 1Axial load from output (P1) = 2400.00 KN 3600Moment about
Z axis (Mz) = 3.333333 KN-m 10Moment about X axis (Mx) = 3.333333
KN-m 10Depth of top of foot. from ground = 1.5 mUnit wt of soil =
18 KN/m
3
Weight of soil retained above foot = 190.08 KNP = (P1+soil+foot
self wt) = 2735.88 KNMaximum bearing pressure = 377.32 KN/m
2
Minimum bearing pressure = 373.26 KN/m2
Hence footing is safe against max gross bearing pr.
DESIGN FORCESFactored load comb. no. 1Axial load:(Pu) = 3600.00
KNMoment about Z axis (Muz) = 10 KN-mMoment about X axis (Mux) = 10
KN-mMaximum effective soil pressure p e max( Pu/Area+ Muz/Zz +
Mux/Zx) = 499.92 KN/m2
Minimum effective soil pressure pe min
( Pu/Area - Muz/Zz - Mux/Zx) = 487.73 KN/m2
Design of footing is done using above maximum effective soil
pressure
x
x
y
y
ZM
ZM
AP
-
CALCULATION FOR BOTTOM STEELMu about X1 X1 = ( pe max x
length
2/2)= 302.45 KN-m per meter
Mulimit = 1840.86 KN-m per meterThe section is singly
reinforced
Hence, Ast = 959.768 mm2
Min Ast = 892.800 mm2
(0.12 % for slab, cl 26.5.2.1)Spacing = 117.84 mm (considering
max of above two calculated values of Ast)pt provided = 0.13 %Hence
provide 12 mm dia bar @ 117 mm c/c parellel to length of footing (
|| to Z)
Mu about N1 N1 = ( pe max x length2/2)= 302.45 KN-m per
meter
Calc. Ast = 959.768 mm2
The section is singly reinforcedMin Ast = 892.8 mm
2(0.12 % for slab, cl 26.5.2.1)
Spacing = 117.84 mm (considering max of above two calculated
values of Ast)pt provided = 0.12900101 %Hence provide 12 mm dia bar
@ 117 mm c/c parellel to breadth of footing ( || to X)Arrangement
of bottom reinforcement as per above design is shown below
12 mm dia bar @ 117 mm c/c
globalZ
globalX
globalX
globalZ
Footing Dimensions
bdbdfM
ffA
ck
u
y
ckst
2
6.4115.0
12 mm dia bar @ 117 mm c/c
1 1
Footing Length 2700 mm Breadth 2700 mm
Sec 1-1
1244 5001244
L1 X1 X
a a
Z ZN1 N1
a a
L2 L2
356 X1 XL1 Breadth 2700 mm
500 Footing Length 2700 mm 356
globalZ
globalX
globalX
globalZ
Footing Dimensions
-
Design of columns:
Columns are designed by taking the forces and moments from the
FEM software. Thesizes of columns are kept constant at all the
stories. The design of column is done consideringthe axial
compression, biaxial bending moment including slenderness effect.
Excel spreadsheets are used for designing of columns as per
standards. The Columns are designed forGF+2 floors.
Axial force, Major BM, Minor BM of typical Column
-
Companys' Name: SafeMatrix India (P) Ltd., Job No.:Muvattupuzha
Design by: PNC
SPREADSHEET OF DESIGN OF RECTANGULAR COLUMN SECTION BY
LIMIT-STATE METHODfor AXIAL COMPRESSIVE LOAD & BIAXIAL BENDING
MOMENT, INCLUDING SLENDERNESSEFFECT, AS PER IS:456-2000, BY N.
PRABHAKARCalculates range of safe loads for a Column Section with
given Concrete grade and Reinforcementand checks adequacy of the
section for the given loads.
Column Dimensions:Breadth, 'b' = 500 mmDepth, 'D' = 500
mmConcrete Grade = M 25Yield Strength of Steel, fy = 500
N/mm2Concrete Cover to main bars = 40 mm
Details of Reinforcement:Diameter of bars = 25 mmNo. of bars on
500 mm face = 4
D
b
X X
Braced Slender ColumnSingle Curvature Double curvature Unbraced
Slender Column(Column with side sway)
Addn. Moments Max & Maydue to slendernessDeflected
shape
Muix1 or
++
-
+
-
Muiy1
No. of bars on 500 mm face = 4No. of bars on 500 mm face =
4Total number of bars = 12Total Ast = 5890 mm2Percentage of
Reinforcement = 2.356 < 4% O.K.
Applied Ultimate Loads Effective Length Un- Braced /Col. Axial
Load Initial Moment Muix(kN.m)Initial Moment Muiy(kN.m)lex (m) ley
(m) Supported UnbracedMk. Pu (kN) M*uix1(+ or -) Muix2 (+ only)
M*uiy1(+ or -) Muiy2 (+ only) Length (m) ColumnCI 4280 11 11 2.000
2.000 2.000 BracedCI 4220 115 28 4.000 4.000 4.000 BracedCI 3470
227 54 4.000 4.000 4.000 BracedCI 2790 168 73 4.000 4.000 4.000
BracedCI 2130 175 71 4.000 4.000 4.000 BracedCI 1540 146 74 4.000
4.000 4.000 BracedCI 1000 145 72 4.000 4.000 4.000 BracedCI 350 185
72 4.000 4.000 4.000 Braced
COLUMNSECTION
(Max. nos. of bar that can beshown in the section at eachface =6
only)
Braced Slender ColumnSingle Curvature Double curvature Unbraced
Slender Column(Column with side sway)
Addn. Moments Max & Maydue to slendernessDeflected
shape
Muix1 or
++
-
+
-
(See figures on next page)
Muiy1
Client: PWD Date: 18-Mar-15Project: Koodal Page No. C/101
-
Note: * at Muix1 and Muiy1 indicates moment is +ve for single
curvature bending, and -ve for double curvature bending.Companys'
Name: SafeMatrix India (P) Ltd., Job No.: 0
Muvattupuzha Design by: PNCClient: PWD Date: 18-Mar-15Project:
Varkala Page No. C/102
For calculations of Final Design Moments, see worksheet on
'Slenderness eff.'.
Summary of Results:
COLUMNSECTION
(Max. nos. of bar that can beshown in the section at eachface =6
only)
D
b
X X
Braced Slender ColumnSingle Curvature Double curvature Unbraced
Slender Column(Column with side sway)
Addn. Moments Max & Maydue to slenderness
Initial Moments Muix & Muiy
Deflectedshape
Muix1 or
Muix2 or
++
-
+
-
Pu
(See figures on next page)
Muix2>Muix1Muiy2>Muiy1
Muiy2
Muiy1
Summary of Results:
Axial Load Final Design Moments Permissible MomentsCol. (kN)
StatusMk. Mux(kN.m) Muy(kN.m) Mux1(kN.m) Muy1(kN.m)CI 4280 88.453
88.453 146.21 146.21 0.732 Section O.K.CI 4220 115.000 104.093 158
158.00 0.964 Section O.K.CI 3470 227.000 85.593 287.43 287.43 0.762
Section O.K.CI 2790 168.000 73.000 371.97 371.97 0.357 Section
O.K.CI 2130 175.000 71.000 438.86 438.86 0.365 Section O.K.CI 1540
146.000 74.000 489.04 489.04 0.349 Section O.K.CI 1000 145.000
72.000 504.87 504.87 0.430 Section O.K.CI 350 185.000 72.000 490.08
490.08 0.524 Section O.K.0 0 0.000 0.000 461.72 461.72 0.000
Section O.K.0 0 0.000 0.000 461.72 461.72 0.00 Section O.K.
See Charts for range of permissible values of Pu with M ux1 and
M uy1.
nn
1uy
uy
1ux
ux
MM
MM
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Design of beams
The RC beams and slabs are designed using Excel spreadsheet
using the analysisresults from FEM software. The top as well as
bottom reinforcement shall consist of at leasttwo bars throughout
the member length.
Bending Moment diagram of typical continuous beam
Shear Force diagram of typical continuous beam
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Design for area of steel and shear for singly reinforced beam by
limit state design method
Calculation of Ast req for beamsRef IS 456-2000 Cl G-1.1b &
G-1.1c For sections without compression reinforcement
fy fck b D Cc Cg of bar d Mu lim pt limN/mm2 N/mm2 mm mm mm mm
mm kN.m %
500 25 200 500 25 8 467 145.03 0.94
Mu support Ast req. spt pt req.spt Mu span Ast span pt
req.spankNm mm2 % kNm mm2 % d req mm d prov mm Result
128.2353 752.97 0.81 133.2353 789.74 0.85 439.13 467 okay
Reinforcement details provided at support and span of beam
Nos. dia Ast support pt support Result Nos. dia Ast span pt
spanmm mm
2 % mm mm2 %2 16 2 162 16 2 16
Check for shear in beams (limit state design method)Ref IS
456-2000 Cl 40.1, Cl 40.2.3, Table 19, Table 20 & Cl 40.2.1
fck Vu pt v c c maxprov. Cl 40.1 Table 19 Table 20
N/mm2 kN % N/mm2 N/mm2 N/mm225 142 0.86 1.52 0.61 3.1
Design for shear reinforcement (vertical stirrups)Ref IS
456-2000 Cl 40.4a
check for depth
Reinf. details at support Reinf. details at span
804.25 0.86
Resulttau_v > tau_c,design for shear
okay 804.25 0.86
tau_v
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Design of slab
Design of slab
Material Constants:
Concrete, fck = 25 N/mmSteel, fy = 500 N/mmLoads:
Using 120 mm thick slab
Dead Load on Slab = 0.12 x 25 = 3 kN/m
Live Load on Slab = 3kN/m
Finishes = 1.5 kN/m
Partition load = 2.5 kN/m
Total =10.0 kN/m
Boundary Conditions one long edge discontinuous
Assume a clear cover of 20 mm & 8 mm dia bars
Eff: depth along shorter direction dx = 96 mm
Eff: depth along longer direction dy = 88 mm
Effective span as per IS 456: 2000 clause 22.2.b
lyeff = 4.67+0.088 = 4.758 m
lxeff = 4+0.096 = 4.096 m
lyeff/lxeff =1.16, Hence design as Two Way Slab.
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1 Design for area of steel and shear for two way slab by limit
state design methodSlab Geometry
Lx Ly Ly/Lxm m
4.096 4.758 1.162
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8 150 8 1500 250 0 150
Moment calculation for '1m' strip of the slab spanning Lyw Lx w
Lx
2
kN/m2 m kNm - y - y w Lx
2 + y + y w Lx2
10.5 4.096 176.16 0.037 6.52 0.028 4.93
Calculation of Ast req for slab spanning LyRef IS 456-2000 Cl
G-1.1b & G-1.1c
- Muy cont. Ast req.cont. pt req.cont. + Muy span Ast min pt
req.spankNm mm
2 % kNm mm2
%6.52 177.52 0.20 4.93 144.00 0.16
Reinforcement details provided at support and span of slab
spanning Ly
dia prov. spacing Ast cont. pt cont. Result dia prov. spacing
Ast spanmm mm mm
2% mm mm mm
2
8 150 8 150okay 335.10
335.10 0.35 okay 335.10
- Muycont. edge 'kNm' + Muy mid-span 'kNm'
Reinf. details at support Reinf. details at span
335.10 0.388 150 8 1500 250 0 250
Check for shear in solid slabs for limit state design methodRef
IS 456-2000 Cl 40.1, Cl 40.2.3, Table 19, Table 20 & Cl
40.2.1.1
fck Vu b D clear cg dN/mm
2kN mm of slab mm cover mm of bar mm mm
25 25.8048 1000 120 20 4 96
pt v k c c maxCl 40.1 Cl 40.2.1.1 Table 20
% N/mm2
N/mm2
N/mm2
0.35 0.27 0.55 3.1
Check for span to depth ratioRef IS 456-2000 Cl 23.2.1
Type of fy span d pt req. pt prov. pc MFtbeam N/mm
2 mm mm % % %Cont.slab 500 4096 96 0.20 0.35 0 2.147
l/d l/d Resultprov Cl 23.2.1 Cl 23.2.1
42.67 55.82 Okay
okay 335.10
Result
tau_v < k tau_c, Oktau_v
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DESIGN OF DOG LEGGED STAIRCASEDataInternal DimensionsLength =
5.32 mWidth = 3.2 mFloor Height = 3.9 mFck = 25 N/mm2
Fy = 500 N/mm2
Riser = 160 mmTread = 280 mmLanding width = 1500 mmEffective
Span = 5.32 mHeight of each flight = 1.95 mNo. of risers in each
flight 12.1875 NosNo. of Tread in each flight 11.1875 Nos
Designd = 168 mm Required
D = 200 mmd = 179 mm
LoadsDL of waist slab = 5 kN/m2
DL on horizontal area = 5.76 kN/m2
DL of steps = 2 kN/m2DL of steps = 2 kN/m2
LL = 5 kN/m2
FF = 1.5 kN/m2
Total load = 14.26 kN/m2
Factored load = 21.4 (of one flight)
BM and SFMu = 76 kN-mVu = 57 kN
d from BM consideration 166 mm
k = 2.362pt = 0.620 %Ast = 1110 mm2
Main ReinforcementDia = 12 mmSpacing = 101 mm
Distribution SteelAst = 215 mm2
Dia of bar = 8 mmSpacing = 230 mm
Development Length
Ld = Ld = ( xs) / (4 x T bd)Therefore, Ld = 583 mmProvide, Ld =
590 mm
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Floor Beam
5320mm
DOWN UP
1500 mm
Mid Landing Beam3200mm
PLAN
Ld = 590 mm
300mm
Y8 @ 230 mm C/C (Distribution Reinforcement)Y12@101 mm C/C(Main
Reinforcement)
200 mm200 mm
DETAILING
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ETABS 2013 Shear Wall DesignIS 456:2000 Pier Design
Pier Details
Story ID Pier ID Centroid X (mm) Centroid Y (mm) Length (mm)
Thickness (mm) LLRFFF P2 2535 18570 5070 200 0.592
Material Properties
E c (MPa) f ck (MPa) Lt.Wt Factor (Unitless) f y (MPa) f ys
(MPa)25000 25 1 500 500
Design Code Parameters
S C IP MAX IP MIN P MAX1.15 1.5 0.04 0.0025 0.8
Pier Leg Location, Length and Thickness
StationLocation
ID Left X 1mm
Left Y 1mm
Right X 2mm
Right Y 2mm
Lengthmm
Thicknessmm
Top Leg 1 0 18570 5070 18570 5070 200
Bottom Leg 1 0 18570 5070 18570 5070 200
Flexural Design for P u, M u2 and M u3
StationLocation
RequiredRebar Area (mm)
RequiredReinf Ratio
CurrentReinf Ratio
FlexuralCombo
P ukN
M u2kN-m
M u3kN-m
Pier A gmm
Top 16128 0.0159 0.0021 DWal12 -606.0331 -16.3907 -9196.8621
1014000
Bottom 28013 0.0276 0.0021 DWal12 -1011.7141 20.2343 -14780.6283
1014000
Shear Design
StationLocation
ID Rebarmm/m
Shear Combo P ukN
M ukN-m
V ukN
V ckN
V c + V skN
Top Leg 1 881.71 DWal8 260.411 -9135.6733 -1777.7813 487.2326
1777.7813
Bottom Leg 1 825.6 DWal8 -138.3875 -14874.4741 -1793.3115
584.8861 1793.3115
Boundary Element Check
StationLocation
ID EdgeLength (mm)
GoverningCombo
P ukN
M ukN-m
Stress CompMPa
Stress LimitMPa
TopLeft Leg 1 600 DWal9 3858.0192 -1944.9148 6.07 5
TopRight Leg 1 900 DWal9 4071.8092 9441.6175 15.03 5
BottomLeft Leg 1 1000 DWal12 -754.2077 -14300.9969 15.95 5
BotttomRight Leg 1 1300 DWal12 4505.0204 14405.2455 21.26 5
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DETAILINGAll the structural elements were detailed according to
IS 456:2000 and SP34. Detailed
drawings were prepared in AutoCAD 2007. Detailing of all the
structural elements were donebased on SP 34 and IS 13920
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COLUMN DETAILSSpecial confining reinforcement as per is
13920:1993
Special confining reinforcement shall be provided over a length
lo from each joint face,towards midspan, and on either side of any
section, where flexural yielding may occur underthe effect of
earthquake forces
The length lo shall not be less than
(a) Larger lateral dimension of the member at
Section where yielding occurs,
(b) 1/6 of Clear span of the member, and
(c) 450 mm.
The spacing of hoops used as special confining reinforcement
shall not exceed 1/4 ofminimum member dimension but need not be
less than 75 mm nor more than 100 mm.
BEAM DETAILING
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Different things which are to be detailed in Beam Detailing is
shown below vide sp 34, page108
SLAB DETAILINGDifferent things which are to be detailed in Slab
Detailing is shown below vide sp 34, page127