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Alpha College of Engineering and Technology
Civil-A Subject- Structure Analysis- 2 Group no-18 Group members- 1) Chaudhary Babubhai ( ) 2) Chaudhary Arvind ( ) 3) Chaudhary Madrup ( ) 4) Jain Mehul ( ) Guided By :- Prof. Vivek Patel Prof. Umesh Dobariya 1
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SINKING FOR SLOPE DEFLECTION METHOD
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SINKING ( SETTLEMENT):
The settlement will be taken as positive, if it rotates the beam as a ᵟ= whole in the clockwise ve direction. The settlement will be taken as negative, if it rotates the beam as a whole in the ᵟ= anticlockwise direction ve
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In this problem A ϴ =0, ϴB≠0, ϴc≠ 0, δ =15mm
Example (1): Analyse the continuous beam ABCD shown in figure by slope deflection method. The support B sinks by 15mm. Solution: In this problem A ϴ =0, ϴB≠0, ϴc≠ 0, δ =15mm
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SINKING ( SETTLEMENT):
FEM: FAB = - wab ˄2 / l˄2 = kn.m FAB = + wa˄2b / l˄2 = kn.m FBC = - wl˄2 / 8 = kn.m FCB = + wl˄2 / 8 = kn.m FEM due to yield of support B
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SINKING ( SETTLEMENT):
Slope deflection equation: MAB = FAB + 2EI / l ( 2ϴA+ ϴB - 3 δ/l ) = /3 EI ϴB- 6 = /3 EI ϴB (1) MBA = FBA + 2EI / l ( 2ϴA+ ϴB - 3 δ/l ) = /3 EI ϴB- 6 = /3 EI ϴB (2)
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SINKING ( SETTLEMENT):
MBC = FBC + 2EI / l ( 2ϴB+ ϴC - 3 δ/l ) = /5 EIϴB + 2/5 EI ϴC - 6 = /5 EIϴB + 2/5 EI ϴC (3) MCB = FCB + 2EI / l ( 2ϴC+ ϴB - 3 δ/l ) = /5 EI ϴC + 2/5 EI ϴB = /5 EI ϴC + 2/5 EI ϴB (4) MCB = - 30 KN.M (5)
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SINKING ( SETTLEMENT):
There are only two unknown rotations ϴBand ϴC. Accordingly the boundary conditions are: MBA + MBC = 0 MCB + MCD = 0 Now, MBA + MBC = /15 EIϴB + 2/5 EIϴC = 0 MCB + MCD = /5 EIϴB + 4/5 EIϴC = 0 Solving the equation we get, ϴB = / EI ϴC = / EI
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SINKING ( SETTLEMENT):
Final Moments: MAB= /3 (-31.35) = KN.M MBA= /3 (-31.35) = KN.M MBC= /5 (-31.35) + 2/5 (-9.71) = KN.M MCB= /5 (-9.71) + 2/5 (-31.35) = KN.M MCD = - 30 KN.M
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SINKING ( SETTLEMENT):
Consider the free body diagram of continuous beam for finding reactions
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SINKING ( SETTLEMENT):
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SINKING ( SETTLEMENT):
Reactions: Span AB: RB × 6 = 100 x – 60.89 RB = 66.85 RA = 100 – RB = KN Span BC: RB × 5 = 20 x 5 x – 30 RB = KN RC = 20 x 5 - RB = KN
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SINKING ( SETTLEMENT):
B.M. diagram: Span AB, M = Wab / l = (100×4×2) / 6 = kn.m Span BC, M = Wl˄2 / 8 = ( 20×25) / 8 = kn.m
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Example (2):Determine the internal moments at the supports of the beam shown in Fig. The support at B is displaced (settles) 12 mm.
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SINKING ( SETTLEMENT):
Solution Two spans must be considered. FEMs are determined using
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SINKING ( SETTLEMENT):
2. SLOPE DEFLECTION METHOD:
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SINKING ( SETTLEMENT):
3. Equilibrium condition:
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SINKING ( SETTLEMENT):
In order to obtained the rotations equations (n) & (p) may then be solved simultaneously, it may be noted that since A is fixed support. Thus, Substituting these values into equations (i to l) yields
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