In urban environments, temporary excavation support systems (ESSs) are intensively recommended during the construction process of structures with underground levels to preserve nearby structures and maintain the excavation sides. Once the foundations and basements are constructed, these systems are rendered useless. As a result, integrating the temporary ESS into the building foundation may have significant benefits. Therefore, the main aim of this paper was to investigate the behavior of Secant Pile Walls (SPWs) through fifteen model tests with an acceptable scale on an axially loaded SPW embedded in medium and dense sand. This study considered several factors to define wall behavior, such as normalized lateral deflection (δh/Ht%), the vertical deflection of the SPW (δvw/Ht%), vertical ground settlement (δv/Ht%), and settlement influence zone (Do). These factors were investigated and analyzed under the influence of a set of parameters including normalized penetration depth (He/Hc), sand relative density (Dr), and surcharge load density (Wsur). The findings demonstrated that SPWs had structural and overall stability features to withstand lateral earth pressures as well as applied axial loads. Generally, increasing the He/Hc ratio further than a limit value of 2.0 for the same surcharge load had a limited impact on the ultimate axial capacity, particularly in the case of dense sand. The location of the pivot point (ε′) extended from 0.24 to 0.41He from the wall tip, with a mean value of 0.34He and 0.29He for the values of Dr = 80 ± 2%, and 60 ± 2%, respectively. Other issues were also discussed for selected samples, including an analysis of the wall's bending moments and any potential wall buckling. Finally, to correlate the experimental data with the theoretical values, a modification factor for the pile static formula was developed by using nonlinear regression analysis with a significant prediction accuracy with an R2 of 0.94.
This paper investigates numerically and experimentally the performance of reinforced concrete (RC) beam with unequal depths subjected to combined bending and shear. Such beams can geometrically be considered for unleveled reinforced concrete (RC) floor slab-beam system. However, it may generate critical disturbances in stress flow at the re-entrant corner (i.e. location of drop in beam depth). This research investigates the use of shear reinforcement and geometric properties to enhance cracking characteristics, yielding, ultimate load-carrying capacity, and exhibiting ductile failure mode. Ten reinforced concrete (RC) beams were constructed and tested experimentally considering the following key parameters: recess length, depth of smaller beam nib, and amount and layout of shear reinforcement at re-entrant corner. Finite element analysis (FEA) with material non-linearity was conducted in two RC beams that were tested experimentally to validate the computer modelling. The FEA models were then extended to conduct a parametric study to investigate the influence of geometric parameters (beam shape and width) and amount and arrangement of shear reinforcement on the structural response. Results confirmed that geometric properties and ratio of shear reinforcement at the re-entrant region significantly affect the behavior of reinforced concrete beam with unequal depths in terms of first cracking, yielding level, ultimate load carrying capacity and mode of failure.
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