Dr. Qais Abdul Mageed Theory of Structures (2008-2009) Page 1 Text Book: Elementary Theory of Structures, 2 nd Edition, by: YUAN-YU HSIEH References: 1. Elementary Structural Analysis, by: NORRIS, WILBAR UTKU. 2. Statically Indeterminate Structures, by: CHU-KIA WONG. 3. Indeterminate Structural Analysis, by: KINNEY First Semester: 4. Stability and Determinacy of Structures: 4.2. Stability and Determinacy of Beams. 4.3. Stability and Determinacy of Trusses. 4.4. Stability and Determinacy of Frames. 4.5. Stability and Determinacy of Composite Structures. 5. Axial Force, shear Force and Bending Moment Diagrams: 5.2. Axial Force, shear Force and Bending Moment Diagrams for Frames. 5.3. Axial Force, shear Force and Bending Moment Diagrams for Arched Frames. 5.4. Axial Force, shear Force and Bending Moment Diagrams for Composite Structures. 6. Statically Determinate Trusses: 6.2. Types of Trusses. 6.3. Stability and Determinacy of Complex Trusses. 6.4. Examples on Solving and Analyzing Trusses. 7. Influence Lines for Statically Determinate Structures: 7.2. Influence Lines for Statically Determinate Beams. 7.3. Maximum Effect of a Function due to external loading: 4.2.1. Due to Concentrated loading. 4.2.2. Due to Distributed loading. • Distributed Dead Load. • Distributed Live Load (occupying any length of the structure). • Distributed Live Load (of a specific length). 4.3. Influence Lines for Girders with Floor Systems. 4.4. Influence Lines for Statically Determinate Frames. 4.5. Influence Lines for Girders in Trusses. 4.6. Influence Lines for Statically Determinate Composite Structures. 4.7. Maximum Effect of a Function due to Multiple External Moving Loads. 5. Absolute Maximum Moment for Simply Supported Beams.
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Dr. Qais Abdul Mageed Theory of Structures (2008-2009)
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Text Book: Elementary Theory of Structures, 2nd Edition, by: YUAN-YU HSIEH References:
4. Stability and Determinacy of Structures: 4.2. Stability and Determinacy of Beams. 4.3. Stability and Determinacy of Trusses. 4.4. Stability and Determinacy of Frames. 4.5. Stability and Determinacy of Composite Structures.
5. Axial Force, shear Force and Bending Moment Diagrams: 5.2. Axial Force, shear Force and Bending Moment Diagrams for Frames. 5.3. Axial Force, shear Force and Bending Moment Diagrams for Arched
Frames. 5.4. Axial Force, shear Force and Bending Moment Diagrams for Composite
Structures.
6. Statically Determinate Trusses: 6.2. Types of Trusses. 6.3. Stability and Determinacy of Complex Trusses. 6.4. Examples on Solving and Analyzing Trusses.
7. Influence Lines for Statically Determinate Structures: 7.2. Influence Lines for Statically Determinate Beams. 7.3. Maximum Effect of a Function due to external loading: 4.2.1. Due to Concentrated loading. 4.2.2. Due to Distributed loading.
• Distributed Dead Load. • Distributed Live Load (occupying any length of the structure). • Distributed Live Load (of a specific length).
4.3. Influence Lines for Girders with Floor Systems. 4.4. Influence Lines for Statically Determinate Frames. 4.5. Influence Lines for Girders in Trusses. 4.6. Influence Lines for Statically Determinate Composite Structures. 4.7. Maximum Effect of a Function due to Multiple External Moving Loads.
5. Absolute Maximum Moment for Simply Supported Beams.
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6. Elastic Deformation of Structures (Deflection & Rotation). 6.1. Conjugate Beam Method. 6.2. Deflection of Beams and Frames. 6.2.1. Unit-Load Method (Virtual Work Method). 6.3. Deflection and Rotation of Trusses. 6.4. Deflection and Rotation of Composite Structures.
Second Semester:
1. Approximate Analysis of Statically Indeterminate Structures: 1.1. Approximate Analysis of Statically Indeterminate Trusses.
• Trusses with Double Diagonal System. • Trusses with Multiple Systems.
1.2. Approximate Analysis of Statically Indeterminate Portals. 1.3. Approximate Analysis of Statically Indeterminate Frames.
• Frames Subjected to Vertical Loads Only. • Frames Subjected to Lateral Loads Only.
2. Symmetry and Anti-Symmetry of Structures. 3. Analysis of Statically Indeterminate Structures by the Method of
Consistent Deformations.
4. Fixed End Moments of some Important Beams with Constant EI.
5. Analysis of Statically Indeterminate Beams and Rigid Frames by the Slope-Deflection Method.
5.1. Analysis of Statically Indeterminate Beams by the Slope-Deflection Method.
5.2. Analysis of Statically Indeterminate Rigid Frames without joint translation by the Slope-Deflection Method.
5.3. Analysis of Statically Indeterminate Rigid Frames with One Degree of Freedom of joint translation by the Slope-Deflection Method.
6. Analysis of Statically Indeterminate Beams and Rigid Frames by the
Moment Distributed Method. 6.1. Fixed-End Moments. 6.2. Stiffness, Distribution Factor and distribution of External Moment Applied
to a Joint. 6.3. Distributed Moment and Carry-Over Moment 6.4. Analysis of Statically Indeterminate Rigid Frames with One Degree of
Freedom of joint translation by the Moment Distributed Method.
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R R R90o
R2R1
F.B.D Link 1
Link 2
Ry
Rx
θ R
θ R
M Rx
M
Ry
Review:
1) Roller: One unknown element.
رد الفعل يكون عمودياً على السطح(2 Degree of Freedom)
2) Link or strut: One unknown element.
(Two Degree of Freedom) 3) Hinge: Two unknown elements.
(One Degree of Freedom)
4) Fixed: Three unknown elements.
(Zero Degree of Freedom)
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1. Stability and Determinacy of Structures: 1.1. Stability and Determinacy of Beams.
(r) = no. of reactions (c) = The total no. of equations of conditions. (Where: c=1 for an internal hinge, c=2 for an internal roller and c=0 for beams without internal connection) (c + 3) = The total no. of the equilibrium equations. The beam is set to be:
3cr +<Unstable
R2
R1
R1 R2
R2
R1
R3 R1 R3 R2
0c,3r ==But Unstable
0c,3r ==Stable & Determinate
R2
R1
R5 R7R4 R6
R3
2m,575323c7
2c,7r
=>=+=+>
==
Stable & Indeterminate to the 2nd degree
• if ( )
3cr +=Determinate if Stable• if ( )
3cr +>Indeterminate if Stable• if ( )
The degree of indeterminacy (m) can be obtained by: ( )3crm +−=
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1.2. Stability and Determinacy of Trusses.
(b) = no. of bar elements of truss (r) = no. of reactions (j) = no. of joints. The truss is set to be:
j2rb <+Unstable
87
8j2,7rb
4j,5b,2r
<
==+
===
(Unstable)
12j2,12rb
6j,9b,3r
==+
===
Stable & Determinate
3m
14j2,17rb
7j,13b,4r
=
==+
===
Stable & Indeterminate to the 3rd degree
• if ( )
j2rb =+Determinate if Stable• if ( )
j2rb >+Indeterminate if Stable• if ( )
The degree of indeterminacy (m) can be obtained by: ( ) ( )j2rbm −+=
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1.3. Stability and Determinacy of Frames.
(b) = no. of frame members (r) = no. of reactions (j) = no. of joints. (c) = The total no. of equations of conditions. (Where: c=1 for an internal hinge, c=2 for an internal roller and c=0 for beams without internal connection) (c = no. of members connected at joint – 1) The frame is set to be:
cj3rb3 +<+Unstable
• if ( )
cj3rb3 +=+Determinate if Stable• if ( )
cj3rb3 +>+Indeterminate if Stable• if ( )
The degree of indeterminacy (m) can be obtained by: ( ) ( )cj3rb3m +−+=
Frame b r j c 3b+r 3j+c Classification
10 9 9 0 39 27
Indeterminate to the 12th
degree
10 9 9 6 39 33
Indeterminate to the 6th degree
Unstable
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1.4. Stability and Determinacy of Composite Structures.
(E) = no. of equilibrium equations (U) = no. of unknowns The structure is set to be:
EU <Unstable
• if ( )
EU =Determinate if Stable• if ( )
• Indeterminate if Stable if ( ) EU >
The degree of indeterminacy (m) can be obtained by: EUm −=
Composite Structure U E Classification
10 10 Determinate
11 9 Indeterminate to the 2nd degree
2. Axial Force, shear Force and Bending Moment Diagrams: Sign convention:
• N: Axial Force (tension +ve, compression –ve) • V: Shear Force (turning structure clockwise +ve, counter clockwise –ve) • M: Bending Moment (compression outside of structure and tension inside
+ve, otherwise –ve)
2.1. Axial Force, shear Force and Bending Moment Diagrams for Frames.
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2.2. Axial Force, shear Force and Bending Moment Diagrams for Arched Frames.
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2.3. Axial Force, shear Force and Bending Moment Diagrams for Composite
Structures.
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١
2
3
4
5
Link
Link
Link
Hinge
Link
3. Statically Determinate Trusses: 3.1. Types of Trusses.
A truss may be defined as a plane structure composed of a number of
members joined together at their ends by smooth pins so as to form a rigid
framework. Each member in a truss is a two-force member and is subjected
only to direct axial forces (tension or compression).
A rigid plane truss can always be formed by beginning with three bars
pinned together at their ends in the form of a triangle.
Common trusses may be classified according to their formation as simple,
compound and complex.
• Simple Truss: ( المسنم البسيط )
A simple truss is formed by a basic triangle; each new joint is connected to
the basic triangle by two new bars.
• Compound Truss: ( المسنم المرآب )
A compound truss is formed from two or more simple trusses connected
together as one rigid framework either by three links neither parallel nor
concurrent, or by a link and a hinge.
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• Complex Truss: ( المسنم المعقد )
The truss which is neither simple nor compound is called a complex truss.
h1
h2
g
3.2. Stability and Determinacy of Complex Trusses.
h1
h2
g
For the shown complex truss there are two cases:
1. If h1=h2=h, then the truss is unstable. 2. If h1≠h2, then the truss is stable.
3.3. Examples on Solving and Analyzing Trusses.
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4. Influence Lines for Statically Determinate Structures:
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4.1. Influence Lines for Statically Determinate Beams.
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4.2. Maximum Effect of a Function due to external loading:
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4.3. Influence Lines for Girders with Floor Systems.
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4.4. Influence Lines for Statically Determinate Frames.
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4.5. Influence Lines for Girders in Trusses.
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4.6. Influence Lines for Statically Determinate Composite Structures.
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4.7. Maximum Effect of a Function due to Multiple External Moving Loads.
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5. Absolute Maximum Moment for Simply Supported Beams.
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)Conjugate Beam Method(المشتقة أو المرتفقةطريقة العارضة ة ذه الطريق تخدام ه ن اس ذه الغرض م ستخدم ه شائية ت وارض الإن ي الع دوران ف و لحساب الهطول وال ه
:ريقة للاسباب التاليةالط
ة المسلطة نتيجة الحقيقي الدوران والهطول للمنشأ التعامل مع تحويل )١ ال الحقيقي ه الأحم ى علي إل
وى ه و القص والعز التعامل مع ق شأ الأصلي مسلط علي شأ مشتق من المن ة م لمن ال المرن الأحم
. الناتجة من التغيرات الحاصلة للمنشأ الحقيقي
.ائي مع قوى القص والعزوم أسهل من تعامله مع التكاملات الرياضيةتعامل المهندس الإنش )٢
ة )٣ ه في عملي الطرق الأخرى تجد تغير واحد من التغيرات الحاصلة للمنشأ ولمقطع واحد معين من
ر من مقطع شأ ولاآث واحدة ، بينما باستخدام هذه الطريقة يمكن ايجاد التغيرات الحاصلة في المن
.في عملية واحدة
ة ) ١(ذنا على سبيل المثال العارضة المبينة في الشكل فلو أخ في أدناه و المسلط عليها حمل مرآز في النهاي
ى ) (الحرة ساوياً إل ة الحرة م EI8(والتي سبق أن حسبنا الهطول في النهايwl 4
P ( ة ا بطريق نقوم بتحليله س
).( Conjugate Method
dxx
x
y
w
A B
RA=wl/2
MA=wl2/2
2wlM
2
A =
wl/2 Shear Force Diag.
Bending Moment Diag.
EI8wl 4
B =Δ
عارضة محملة بحمل منتظم–) ١(شكل
Curvature :في أي نقطة من العارضة يمكن حسابه من المعادلة التالية) (ات سابقة أن التغير نعلم من دراس
EIM
dxyd2
2
−=
:بأن الميل أو الدوران في أي نقطة من العارضة يمكن حسابه من المعادلة التاليةأيضاً ونعلم
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θθ ≈= tandxdy
:يليوهكذا للتغيرات الصغيرة نسبياً نجد ما
EIM
dxyd
dxddxdy
2
2
−==
=
θ
θ
:وباجراء عملية التكامل نحصل على
∫−= EIMθ dx ------ (1)
dx(بالقيمة ) θ(الآن بتعويض dy
( : ∫−==EIM
dxdy
θ dx
dxEIMdxdy ∫−== θ dx
:ثم نكامل مرة أخرى نحصل على
∫∫∫ −== dxEIMdxy θ dx ------ (2)
ين الحمل ، ) ١(من العارضة في الشكل ) dx(والآن بأخذ شريحة بعرض ات ب والتي بالإمكان آتابة العلاق
: قوى القص وعزم الإنحناء آما يلي
∫−=⇒−=⇒−= wVdxwdVwdxdV dx
∫∫∫ −==⇒=⇒= dxdxwdxVMdxVdMVdxdM
: عليه فعلى مقطع من العارضة فإن
------ (٣) ∫−= wV dx
dx ------ (4) ∫∫∫ −== dxwdxVM
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دينا سميها ل عارضة والآن لنفرض ان ل ة ن ا نفس ) Conjugate beam ( العارضة المرتفق طول والتي له
شكل ي ال لية ف ة الأص ة و) ١(العارض ا محمل ى با لكنه ساوي إل رن الم ل الم (لحم
(w) per unit length
(a)
(b) (Conjugate Beam)
EI2wl 2
EI6wl
3l
EI2wlttansulRe
32
=⎟⎠⎞
⎜⎝⎛⎟⎟⎠
⎞⎜⎜⎝
⎛=
MB
A B
( ) l4/3
ΔBl
A B
المرتفقةالعارضة والعارضة الأصلية -) ٢(شكل
EIM
ي ) ين ف ا مب وآم
فقة والتي نرمز ، فإن المصطلحات التكاملية لقيم القص وعزم الإنحناء لمقطع العارضة المرت ) b٢-(الشكل
w(لها VM ( على التوالي يمكن ايجادها من خلال تبديل قيم) ادلات ) (و ) ة ) ٤(و ) ٣(في المع بالقيم
)EIM
:آما يلي)
∫−= dxEIMV ------ (5)
∫∫−= dxdxEIMM ------ (6)
اً ) ٢(و ) ١(مع المعادلات ) ٦(و ) ٥(بمقارنة المعادلات ستنتج وفق ه ن ة نجدها متشابهة وعلي شروط معين ل
:ملائمة للعارضة المرتفقة مايلي
V=θ دوران) ( .١ ل أو ال ين المي ل مع ة بحم لية المحمل ة الأص ن العارض ين م ع مع لمقط
)Actual Beam ( ون ساوياًيك ة م ص لقيم ة الق ة المرتفق ى العارض ع عل نفس المقط ل
)Conjugate Beam (والمحملة بالحمل المرن.
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My = ول)( .٢ ة الهط لية المحمل ن العارضة الأص ين م ع مع ينلمقط ل مع Actual ( بحم
Beam ( ون ساوياًيك ة م اء لقيم زم الإنحن ة ع ة المرتفق ى العارض ع عل نفس المقط ل
)Conjugate Beam (والمحملة بالحمل المرن.
ة .٣ اً للعارضة الأصلية) Conjugate Beam(ان العارضة المرتفق ة تمام Actual (مطابق
Beam ( تم إجراء . من حيث الطول ا في أعلاه يجب أن ي اط التي بيناه ولغرض تحقق النق
دِث بحيث ) Conjugate Beam(تغييرات على المساند ونقاط الإرتباط للعارضة المرتفقة يُحْ
ه ذي تحدث ل أو الهطول ال سجماً مع المي ا بحيث يكون من اء فيه الأجزاء قوة قص وعزم إنحن
ة في الجدول ). Actual Beam(لها في العارضة الأصلية النظيرة رات مبين ذه التغيي ) ١(ه
:والتي يمكن تلخيصها بما يلي
Fixed End Free End
Simple End Simple End Interior Connection Interior Support
ضة المرتفقة التغييرات الواجب إجراؤها لتحويل العارضة الأصلية إلى العار–) ١(جدول
Actual Beam Conjugate beam (Subjected to applied Load) (subjected to Elastic Load)
00
==
Δθ
0M
0V
=
=Free End Fixed End
00
≠≠
Δθ
0M
0V
≠
≠Fixed End Free End
00
=≠
Δθ
0M
0V
=
≠ Simple End Simple End (hinge or roller) (hinge or roller)
00
=≠
Δθ
0M
0V
=
≠ Interior Connection Interior Support (hinge or roller) (hinge or roller)
00
≠≠
Δθ
0M
0V
≠
≠ Interior Support Interior Connection (hinge or roller) (hinge or roller)
Sign Convention( الإشارات المتفق عليها:)
ة سرى للعارضة مع فرض : تم إتباع الفرضية التالي ة الي ة تكون في النهاي نقطة الأصل للعارضة المحمل
ي الهطول الموجب وبذلك فإن موجب إلى اليمين ) x(اتجاه الهطول إلى الأسفل موجباً و إتجاه هطول يعن
.دوران مقطع العارضة باتجاه عقرب الساعةي يعنوالدوران الموجب إلى الأسفل
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):Conjugate Beam Method(خطوات الحل بطريقة العارضة المرتفقة
.للمنشأ الأصلي المعطى) BMD(نستخرج مخطط العزم )١
.نرسم العارضة المرتفقة بنفس طول العارضة الأصلية مع إحداث التغييرات اللازمة للمساند )٢