Proposed Method for Cost Assessment of Seismic Mitigation Designs for Reinforced Concrete Buildings According to ECP Code

Abstract

The Earthquake can be considered as a natural phenomenon or a disaster based on the seismic response of structures during a severe earthquake that plays a vital role in the extent of structural damage and resulting injuries and losses. It is necessary to predict the performance of the existing structures and structures at the design stage when it subjected to an earthquake load. Also, it is needed to predict the repair cost required for the rehabilitation of the existing buildings that is insufficient in seismic resistance, and the construction cost and the expected repairing cost for the structures at the design stage that designed to have a ductile behavior with acceptable cracks. This study aims to propose a method for seismic performance evaluation for existing and new structures depending on the width of cracks resulted from the seismic exposure. Also, it assesses the effect of building performance during earthquakes on its life cycle cost. FEMA 356 criteria were used to predict the building responses due to seismic hazard. A case study of seven-story reinforced concrete building designed by four design approaches and then analyzed by static nonlinear pushover analysis to predict its response and performance during earthquake events using Sap 2000 software. The first design approach is to design the building to resist gravity loads only by using ECP code. The second one is to design the building to resist gravity loads and seismic loads by using static linear analysis according to ECP code. The third one is to design the building to resist gravity loads and seismic loads by using static linear analysis according to the regulations of the Egyptian Society of Earthquake Engineering (ESEE). Finally the fourth one is to design the building as the second approach but with ground acceleration greater by five times than it or by using ductility factor R = 1. The methodology followed in this study provides initial How to cite this paper: Fayed, Y., Sobaih, M.E. and El Hakem, Y.

Response Reduction Factor for Structures with Significant Irregularities on Different Soil Stratum

“…The concept behind the response factor is to integrate nonlinearity with the overstrength, redundancy, and ductility of a structure to accurately assess the seismic force. Figure 1 illustrates the relationship between a structure's base shear (total horizontal load) and its roof displacement, as described by [1][2][3] for nonlinear static analysis. The reduction factor is typically expressed as a function of various structural system factors, including strength, ductility, damping, and redundancy.…”

“…A structure must be able to withstand intense seismic events without collapsing suddenly, even though it may suffer some structural and nonstructural damage. This is the core principle of earthquake -resistant design, which involves constructing a structure to withstand seismic forces by dissipating energy a nd exhibiting inelastic behavior [1][2][3]. Recent earthquakes have shown that elastic analysis is inadequate for assessing the true seismic performance of reinforced concrete buildings.…”

“…If the modification factor is overestimated, it can lead to a reduction in base shear and potentially result in more economical design solutions. However, precautions should be taken to ensure the structure's ductility performance [2][3][4]. Conversely, underestimating R could lead to uneconomical structural designs.…”

“…The structural systems of buildings often need to incorporate various geometric irregularities, either in the horizontal or vertical plane, as specified by architectural requirements. Many existing structures exhibit severe irregularities that may not be addressed by current design codes, necessitating thorough research for their proper design [3]. Past experiences have shown that irregular constructions are more prone to catastrophic damage during earthquakes compared to regular structures [11].…”

“…These values need to be adjusted to accommodate severe irregularities. Fayed et al [3] calculated behavior factor values at failure for idealized multistory frame systems with moment resistance made of RC and developed in compliance with ECP-201 (2012) [13]. A decrease in the stated R values was observed.…”