Analysis of Reinforced Concrete D-Regions Using Strut-and-Tie Model

Mohamed Husain, Hilal Abd El-Kader Hassan, Mahmoud Khater, Amr Ghoniem

Abstract


The developed Strut-and-Tie Model (STM) has no unique shape for each load case of a given structural problem as long as the selected idealized internal load-resisting truss is in equilibrium with boundary forces, and also stresses in its components "struts, ties, and nodes" are within acceptable limits. However, the optimal shapes are the well-designed with best ordinal weight number of conditional factors as the rebar amount, the load factor, and the structural concrete ductility. The current study investigates numerically based on FE method stress flow contours and micro truss techniques many alternatives with different shapes of struts and ties that transfer the flow of forces from top of the deep beam with opening to both right and left supports. Then, these alternatives with different concrete characteristics are analyzed by strut-and-tie computational tools using different code provisions for verifying its results accuracy with the numerical nonlinear finite element analysis results for studying the structure performance under applied service loads and over loading till failure. The chosen alternative produce load factor to reach capacity greater than 1, therefore the strut-and-tie method always give demand collapse load lower than the true capacity collapse load. This implies that the solution obtained from STM usually lies on the safe side with conservative sense for concrete structures subjected to service loads. That’s why the STM is emerging as an increasingly popular code-worthy methodology for the design and detailing of concrete structures D-Regions.

Keywords


D-regions. Strut-and-tie. STM. Strut-and-tie computational tool. CAST. Numerical nonlinear finite element analysis. ANSYS. Reinforced concrete deep beam. Optimal shape.

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