Publication: Progressive collapse behavior of rubberized steel fiber concrete frame
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Date
2020-10-01
Authors
Alshaikh, Ibrahim Mohammed Hasan
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Abstract
Given the large economic losses and extensive casualties caused by progressive collapse, researchers began to conduct further studies to advance the understanding of the behavior of structures under column removal scenarios. However, most of the experimental studies were conducted and focus on reinforcement rebars such as adding rebar layers or seismic detailing for mitigating progressive collapse. On the contrary, there is a lack of related data available regarding the use of special concretes and economical and environmental solutions at the same time (especially adding a crumb rubber and steel fibers). The influence of these materials in the concrete mixtures to resist progressive collapse has not been considered in previous studies. Reviewing the literature has shown that the incorporation of crumb rubber, steel fibers, and their combination into the concrete mixtures resulted in improving deformability, ductility, flexural capacity, energy dissipation, and strain capacity. As a result, this can increase the resistance of progressive collapse or even mitigate it. In this study, experimental and numerical tests were conducted to investigate the influence of crumb rubber and steel fibers in concrete mixtures in resisting progressive collapse. Size of crumb rubber between 1-2 mm (20% replacement of fine aggregate) and 0.5% of micro steel fiber with aspect ratio of 60 were used. The progressive collapse was simulated by assuming that the middle column had lost part of it through abnormal loadings when a static load was applied on the column through a hydraulic actuator. The test, under load control, was quasi-static by increasing the middle column displacement until complete specimen failure. The behavior of progressive collapse was numerically simulated using ABAQUS-explicit and validated by comparing the FEM results with the experimental test observations. In addition, eighteen (18) new models were non-linearly analyzed using the calibrated numerical model. The experimental results showed that there was more deflection beyond the maximum load (reaching up to 29.53%) resulting in the improvement of the entire structural ductility factors (reaching up to 58.29%) as a result of incorporating crumb rubber, steel fibers, and their combination. In conclusion, rubberized concrete and steel fiber rubberized concrete can be used as an eco-friendly building material for enhancing the ductility of RC elements as a new design strategy and thus preventing progressive collapse. In addition, the provided numerical models were successfully implemented to simulate different geometries of structures in a very realistic and accurate manner and satisfied the resistance requirements of progressive collapse according to the guidance.