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

Abstract

The developed Strut-and-Tie Model (STM) has no unique shape for each load caseof a given structural problem as long as the selected idealized internal load-resistingtruss is in equilibrium with boundary forces, and also stresses in its componentsstruts, ties, and nodes are within acceptable limits. However, the optimal shapesare the well-designed with best ordinal weight number of conditional factors as therebar amount, the load factor, and the structural concrete ductility. The currentstudy investigates numerically based on FE method stress flow contours and microtruss techniques many alternatives with different shapes of struts and ties thattransfer the flow of forces from top of the deep beam with opening to both right andleft supports. Then, these alternatives with different concrete characteristics areanalyzed by strut-and-tie computational tools using different code provisions forverifying its results accuracy with the numerical nonlinear finite element analysisresults for studying the structure performance under applied service loads and overloading till failure. The chosen alternative produce load factor to reach capacitygreater than 1, therefore the strut-and-tie method always give demand collapse loadlower than the true capacity collapse load. This implies that the solution obtainedfrom STM usually lies on the safe side with conservative sense for concretestructures subjected to service loads. That’s why the STM is emerging as anincreasingly popular code-worthy methodology for the design and detailing ofconcrete structures D-Regions.