Numerical investigations on progressive collapse of rubberized concrete frames strengthened by CFRP sheets

Abnormal loads have the potential to cause localized damage, which can eventually lead to progressive collapse of reinforced concrete structures. This, in turn, can result in casualties and trigger catastrophic financial consequences. To save time and avoid the high costs and potential risks of experimental tests, numerical simulation of the effects of abnormal loads on structures using the finite element (FE) method is, therefore, necessary. In this paper, two concrete mixtures, including normal concrete (NC) and rubberized concrete (RuC) were utilized to numerically examine the progressive collapse resistance of NC and RuC frames strengthened by CFRP sheets using ABAQUS-Explicit. A comparison has been conducted between the numerical results of this study and available experimental results to improve and validate the FE models' accuracy and reliability. To this end, twenty-six FE models were generated based on the validated FE models with different specifications (i.e., five schemes of CFRP wrapping) to further comprehend the mechanism of resistance to progressive collapse. The CFRP composites demonstrated high efficiency in improving the progressive collapse resistance compared to the un-strengthened specimens by increasing the ultimate load and energy absorption, thereby preventing, and delaying the reinforcing bars' fractures, reducing concrete crashing at the joint interfaces, and increasing the catenary force contribution.