Investigating the Effect of Vertical Component of Earthquake on Seismic Responses of Concrete Slabs with Opening

One of the most important factors in the design of the structures is providing seismic resistance against earthquakes-induced forces. Buildings might be subjected to stimulations of earthquake seismic components, which affect the structure in three perpendicular directions. In estimations of the earthquake forces, the vertical component is usually neglected or understated. However, the earthquake vertical component can lead to drastic stress changes in the structural elements, especially the concrete slabs with opening. In this study, the effect of earthquake vertical component on concrete slabs with opening has been investigated. Three concrete structures with 5, 8, and 12 stories and slab openings of 0, 15, 30, and 45 percent were subjected to the effect of the near-field record of Bam, Northridge, and El Centro earthquakes. Non-linear time history analysis was used to comparatively study the structural displacements and stresses. The results indicated that the contribution of vertical earthquake component in slabs displacements was not significant compared to that of three direction combination. On the other hand, it was inferred that the acquired stresses have a direct relationship with deformations generated in the slabs, so that in models with larger displacements, higher stress levels were detected. For both the three direction combination and the vertical direction earthquakes, increasing the opening percentage would result in growing more stress in concrete slabs. Generally, the maximum produced stress in the slabs was in some cases about sixty percent of the maximum stresses induced by three directional combined earthquakes.