“A Comparative Analysis of the Concentrated Plasticity, the Yielded Block Spread Plasticity, and the Spread cracking and yielding block Pushover analysis models”

Abstract

Pushover analysis is mainly carried out using the concentrated plasticity model where by when a point reaches yield, a hinge is placed at that point. The other is the yielded block spread plasticity model, whereby when a point reaches yield, an elastic sub-element of the beam is replaced by a yielded block sub-element having a reduced cross section and second moment of area. Both of these models ignore cracking. This research seeks to determine the effect of considering cracking during modelling on the accuracy of estimating deformations in RC structures during pushover analysis by proposing a spread cracking and yielding block model. For the single storey frame, a comparison between the proposed model and the yielded block spread plasticity model indicates an improvement in accuracy of the joint rotational, displacement, moment and lateral load capacities of the frame by 27.81%, 13.46%, 2.035% and 6.26% respectively in favour of the proposed model. The proposed model in comparison to the concentrated plasticity model, leads to an improvement in accuracy of the joint rotational, displacement, moment and lateral load capacities of the frame by 58.01%, 56.59%, 53.69% and 55.56% respectively. For the three storey frame, a comparative analysis of the deformations given by both the proposed model and the yielded block spread plasticity model indicates that there is an improvement in accuracy of the joint rotational and moment capacities of the frame by 66.67% and 37.2% respectively at some joints. Comparing the proposed model with the concentrated plasticity model, indicates that there is an improvement in accuracy of the joint rotational and moment capacities of the frame by 150% and 102.98% respectively at some joints. The improvement in accuracy of floor displacements and inter-storey drift ratios is negligible. The accuracy of the lateral load capacity of the frame improves by 33.9%.