Full Scale Load Testing BPEX Project, Maptaphut Rayong

9.2 AT FIRST YIELDINGAfter cracking, the stress‐strain relationship of concrete is assumed to be parabolicup to failure, as shown below:bStrain of concretedhd’c-d’φd-cCsCcTStrain of steelBeam SectionStrain DistributionStress DistributionThe compression force in concrete is obtained by integration of parabola stressblock:Ccf bφc⎛ φc⎞⎜1−⎟⎝ 3ε⎠' 2=cε00εcφ =c0.002=d − cAt yielding, tension force in steel is:T = A sfyEquating compression force in concrete and tensile force in steel and solve forneutral axis depth to get c = 318 mm.ε = 0.002cc0.0012d−c=The c.g. of compression force is obtained from:8ε0− 3εcx =12ε− 4ε0c= 202mm22