Seismic fragility curves for mid-rise reinforced concrete framed structures with different lateral loads resisting systems

The current study presents lateral load analysis of mid-rise reinforced concrete framed structures with two different lateral load resisting systems; shear walls and rigid marginal beams. The main objective here is to investigate the influence of the location of the system in the structure; i.e. arrangement of shear walls and level of the marginal beam. For that purpose, seismic fragility curves are used as an assessment tool for comparing the seismic performance of the studied structures in different situations. Incremental dynamic analysis was performed under ten ground motions to determine the yielding and collapse capacity of each building. Five performance levels were considered in the analysis. These performance levels are (i) operational, (ii) immediate occupancy, (iii) damage control, (iv) life safety and (v) collapse prevention. Fragility curves were developed for the structural models of the studied structures considering the previously mentioned performance levels. It was observed that arrangement of shear walls on the long direction of the structure has insignificant effects on its performance while interior shear walls provide the best behavior of the structure compared to exterior shear walls only and distributing shear walls internally and externally. The analysis outcomes also indicated that the presence of the rigid marginal beam in the lower storey gives more efficiency regarding to lateral loads resistance in the studied structure

Experimental and numerical study of the behavior of RC slabs with openings reinforced by metal mesh under impact loading

The main objective of the following work is to inspect the effect of reinforcing metal mesh on the behavior of slabs with openings under impact loadings. Based on an earlier numerical study by Shaheen et al. (2017), slabs with mid-side openings revealed the worst behavior regarding to deflection and cracked pattern when subjected to impact loading compared to other slabs with different locations of openings. Hence, the present work focuses specifically on this type of slabs and the variation in their behavior when reinforced by welded or expanded metal mesh. Seven specimens were prepared and tested in Faculty of Engineering, Menoufia University, Egypt. Moreover, a FE model for the slabs was built using Abaqus 6.14 and verified against test results. It was found that expanded metal mesh had a significant effect on reducing deflection due to impact load as well as controlling of cracks in contrast with welded metal mesh

Modeling of Dowel Jointed Rigid Airfield Pavement under Thermal Gradients and Dynamic Loads

Concrete pavements have been widely used for constructing runways, taxiways, and apron areas at airports. The aviation industry has responded to increased demand for air travel by developing longer, wider, and heavier aircraft with increasing numbers of wheels to support the aircraft while in ground operation. Many researchers developed their models based on the finite element method (FEM) for the analysis of jointed concrete pavement. Despite the notable improvement, important considerations were overlooked. These simplifications may affect the results of the developed models and make them unrealistic. Sensitivity studies were conducted in this study to investigate the effect of the loading parameters on the load transfer efficiency (LTE) indictors where concept of LTE is fundamental in airfield design procedures.  The effect of main gear loading magnitudes in different wheel configurations combined with positive and negative thermal gradients was investigated. The verification process was presented to increases the confidence in the model results. Understanding the response of rigid airfield pavement under such circumstances is important developing a new pavement design procedure, as well as implementing a suitable remedial measure for existing pavements. The results obtained that utilizing a dynamic load allows studying the fatigue cycles that pavement can be subjected under different wheel configurations.   Moreover, the change in the thermal gradient from positive to negative significantly changed the slab curvature shape