Earthquake resistant structures

About: Earthquake resistant structures is a research topic. Over the lifetime, 1126 publications have been published within this topic receiving 27467 citations.

Simplified Method for the Seismic Analysis of Masonry Shear-Wall Buildings

Abstract: In this paper, an improved version of a simplified method to assess lateral shear forces attracted by shear walls of regular, low-rise masonry structures is presented. This simplified method for seismic analysis SMSA is allowed by Mexican building codes since the 1970s. The impact of shear deformations in the three-dimensional distribution of the forces absorbed by these walls is assessed for different wall aspect ratios H / L. Based on extensive parametric studies, effective shear area factors FAE originally proposed in the SMSA are modified to improve the estimates of shear forces using this method. New FAE are proposed for three different performance levels for the structure: 1 elastic response; 2 completely nonlinear cracked response of all walls along the building height; and 3 partially nonlinear cracked response along the height.

Benchmarking Seismic Performance of Reinforced Concrete Frame Buildings

Abstract: With the ultimate goal to benchmark the seismic performance of new (building-code compliant) reinforced concrete frame structures, we have applied a probabilistic assessment methodology, developed by the Pacific Earthquake Engineering Research Center, to a four-story office building. A key component of the assessment is characterization of the structural response through nonlinear time history analyses organized using an Incremental Dynamic Analysis approach. The results show that the seismic performance of the building is generally consistent with the expectations of current building codes, having a life-safety performance level (ASCE 356) for the 2% in 50 year event. A sensitivity study shows that the record-to-record variability is the single most important contributor to the total variability in structural response; however, the cumulative affect of other modeling and design uncertainties is also shown to be significant – resulting in the total dispersion being roughly double the dispersion due to record-to-record effects. To further investigate modeling uncertainties, we have compared the responses predicted by using a force-based fiber model and a lumped plasticity model. These comparisons show that the concrete tensile strength and tension stiffening effect significantly impact the response predictions, especially for structures with highly under-reinforced members subjected to lower ground motion intensity levels.

Behavior of Externally Confined Concrete Columns

Abstract: This paper investigates the feasibility of strengthening of seismically deficient concrete columns with high-strength fiber composite straps. The concrete columns will be externally confined by wrapping thin glass-fiber-reinforced or carbon-fiber-reinforced straps around the column. The confinement provided by the straps will increase the stress and strain of concrete at failure and will increase its ductility. Moreover, the composite strap will prevent buckling of longitudinal bars and spalling of the shell and therefore will further increase the load carrying capacity of the column. Analytical models are developed and a seismically deficient parametric study is conducted to investigate the effectiveness of this technique for strengthening of concrete columns designed before the new seismic design provisions and codes were in place. The variables used in the parametric study include, concrete compressive strength, thickness of composite strap, clear spacing between composite straps and type of the composite strap, i.e., carbon fiber reinforced or glass fiber reinforced. The results indicate that external confinement provided by the composite straps significantly increases the strength and ductility of concrete columns.

Experimental Evaluation of Pretopped Precast Diaphragm Critical Flexure Joint under Seismic Demands

Abstract: Precast concrete diaphragm seismic response is examined in experimental research integrating model-based simulation with physical testing. The experimental substructure is the diaphragm critical flexural region of a prototype precast parking structure. This region is expected to undergo significant inelastic flexural deformation, while potentially nonductile regions remain elastic on the basis of capacity design rules from an emerging design methodology. The physical test is conducted at half-scale. The test specimen is detailed using diaphragm reinforcement intended to meet deformability requirements. Predetermined displacement histories are applied to the test specimen on the basis of nonlinear transient dynamic analyses of the prototype structure. The loading history is applied by a test fixture capable of simultaneously providing shear, axial, and moment to the joint. Moment strength, stiffness, rotational deformation capacity, and progressive damage are examined under a sequence of increasing intensity earthquakes. Design recommendations are provided.