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Go to Editorial ManagerConcrete roof-folded plates have been shown to be inherently resilient to earthquakes, despite limited research on the reasons for their apparent seismic resistance. It is possible to make very thin, folded concrete plates because of their high structural efficiency. It is implicitly resistant to earthquake forces because thin, folded plat structures are relatively lightweight. Typically, folded plate structures are designed to perform under ideal gravity loads that are transported primarily as a result of membrane activity across the surface. It is possible for concrete-folded plate structures to be damaged by bending stresses when earthquakes induce unexpected horizontal forces. Through a parametric analysis of an 8-cm-thick concrete roof folded plate structure, it has been shown that thin concrete roof folded plates with a span < 30 m can be intrinsically earthquake-resistant. Despite having a low mass and high geometric stiffness, these buildings have fundamental frequencies that are substantially higher than those connected to seismic events that actually occur. This characteristic causes the folded plate to behave elastically under earthquake excitation without exceeding the maximum concrete strength. The vertical components of earthquake vibrations exert greater stress on a shallow, folded plate than the horizontal components. The values of the stresses imposed by the changing span were relatively small. They ranged from (3.5-4.4) MPa for the Landers earthquake, while for the El Centro earthquake, they ranged from (2.7-8.6) MPa. In addition, by raising the folded big plates and inclining them to a greater angle, it will become more common and lessen the harm caused by earthquake shaking in the vertical direction. In general, this paper aims to present an examination of earthquakes and their consequences for folded concrete plates.
The objective of the present paper is to evaluate the effects of the soil-structure interaction on the seismic evaluation in the building when a framed building is supported on raft foundation. Also the foundation-soil interaction effect has been considered by replacing it with equivalent springs. Nonlinear static pushover analyses of eight-storey reinforced concrete hospital building located at Delhi-India has been performed using the Capacity Spectrum Method of ATC-40. The deformations define the state of damage in the structure through three limit states of the NEHRP Guidelines and the FEMA-356 have been used to evaluate the performance level of the building for drift, the plastic hinge stage of the crack and shear under the condition of the fixed base and the effect of the soil-structure interaction. The performance of the building and individual components has been estimated for Design Basis Earthquake and Maximum Considered Earthquake. The weight of the slab was distributed as triangular and trapezoidal loads to the surrounding beams as per IS 456:2000. The weight of the brick masonry was distributed uniformly on the beams. The results show that the soil structure interaction has marked effect on the roof displacement, storey drift, design base shear, effective damping and crack pattern for beams and columns while there is a minor effect on the torsional behavior of the building. The building is more critical in the performance level when considering the soil flexibility.
The goal of the present paper is to study the adequacy of torsional provisions in the international buildings code (IBC) for irregular building taken into account effect of the angles of seismic attacks. The responses of the frame-shear-wall twelve- story asymmetric building under earthquake loading by using equivalent lateral force procedure and dynamic response spectrum analysis have been studied intensively in this present research paper. This study performs static and dynamic response analyses of building models under earthquake ground motions compatible with the design response spectrum defined in the international buildings code. The dynamic response spectrum was scaled according to the code static base shear. The static and dynamic base shear with different angles of seismic attacks has been calculated. The scaling factors, angles of seismic attacks, accidental storey torsions, storey shear, dynamic and static base shear have been evaluated here. The torsional moment at different storey levels for dynamic analysis has been estimated and compared with the static values.