Alaa G. Sherif

Punching Strength of Reinforced Concrete Footings

This study investigates the punching shear behavior of reinforced concrete footings. Punching tests were conducted on 17 reinforced concrete footings were tested to study the parameters assumed to affect the punching shear strength of footings. These parameters included shear span-depth ratio (a/d), concrete strength, and punching shear reinforcement. The (a/d) ranged between 1.25 and 2.0, while the concrete strength ranged between 20 and 40 MPa (2.9 and 5.8 ksi). To study the effect of soil-structure interaction, five footings were realistically supported on sand. The remaining specimens were supported on a column stub and a uniform surface load was applied. The present experimental investigations indicated that the angle of the failure shear crack is steeper in punching tests on compact footings than observed in tests on more slender slabs. Furthermore, the (a/d) significantly affects the punching shear capacity. The provisions of ACI and Eurocode 2 are evaluated by comparing them with experimental results. Modifications are proposed to overcome the deficiencies of these codes.

Simplified Punching Shear Design Method for Slab-Column Connections Using Fuzzy Learning

This paper presents a new approach for predicting the punching shear strength of concentrically loaded interior slab-column connections using fuzzy learning. A total of 178 experimental datasets obtained from concentric punching shear tests of reinforced concrete slab-column connections from the literature are used in training and testing of the fuzzy system. The fuzzy-based model is developed to address the interaction between various punching shear modeling parameters and the uncertainties between them, which might not be properly captured in classical modeling approaches. The model is trained using 82 datasets and verified using 96 datasets that are not used in the training process. The punching shear strength predicted by the fuzzy-based model is compared with those predicted by current punching shear strength models widely used in the design practice. The fuzzy-based model demonstrates a higher prediction of the punching shear strength of concentrically loaded interior slab-column connections than all current design codes. It also respects the fundamental failure mechanics of punching shear that have been observed by previous researchers. The authors also propose a simplified design model based on a set of design charts that were developed from the fuzzy-based model.

Assessment of vehicular live load and load factors for design of short-span bridges according to the new Egyptian Code

Abstract The new Egyptian Code (ECP-201:2012) introduces new vehicular live loads (VLL) and new load combinations for the design of roadway bridges. The new VLL and load combinations introduced in ECP-201:2012 are fundamentally different than those presented in previous versions of the code. The impact of these new loads and load combinations on the design of new bridges or the structural safety of the existing bridges that have been designed according to ECP-201:2003 or ECP-201:1993 has not been fully addressed for the different bridge deck systems. Three different bridge deck systems, i.e. concrete I-shaped girders, composite steel plate girders, and concrete box-girders with different spans were numerically modeled using two-dimensional grillage analogy. The bridge decks were analyzed under main gravity loads using VLL according to ECP-201:2012 and ECP-201:2003. The internal forces of individual load cases, total un-factored load combination, and total factored load combination of ECP-201:2012 and ECP-201:2003 were compared. The study shows that concrete box-girders designed according to ECP-201:2012 and ECP-201:2003 using the ultimate limit state method yield almost the same demand. Despite the increase in the VLL of ECP-201:2012, and consequently the live load forces, concrete I-shaped girder bridges will be subjected to less total factored internal forces in comparison to ECP-201:2003 This is attributed to the interaction between the live to dead loads ratio and the load combinations. Design of composite steel plate girder bridges according to ECP-201:2012 using the allowable stress design method yields over designed sections.