• Structural Engineering and Mechanics
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• 제88권5호
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• pp.419-437
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• 2023

The use of reinforced concrete (RC) shear walls (SW) as an efficient lateral load-carrying system has gained recent attention. However, creating openings in RC shear walls is unavoidable due to architectural requirements. This reduces the walls' strength and stiffness, resulting in the development of wall piers. In this study, the cyclic behavior of RC shear walls with openings, reinforced with carbon fiber reinforced polymer (CFRP) sheets in various patterns, was numerically investigated. Finite element analysis (FEA) using ABAQUS software was employed. Additionally, the retrofitting of sub-standard buildings (5, 10, and 15-story structures) designed based on the old and new versions of the Iranian Code of Practice for Seismic-Resistant Structures was evaluated. Nonlinear static analyses, specifically pushover analyses, were conducted on the structures. The best pattern of CFRP wrapping was determined and utilized for retrofitting the sub-standard structures. Various structural parameters, such as load-carrying capacity, ductility, stress contours, and tension damage contours, were compared to assess the efficiency of the retrofit solution. The results indicated that the load-carrying capacity of the sub-standard structures was lower than that of standard ones by 57%, 69%, and 67% for 5, 10, and 15-story buildings, respectively. However, the retrofit solution utilizing CFRP showed promising results, enhancing the capacity by 10-25%. The retrofitted structures demonstrated increased yield strength, ultimate strength, and ductility through CFRP wrapping and effectively prevented wall slipping.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.322-329
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• 2000

Current seismic design codes for building structures are based on the methods which can provide enough capacity to satisfy objected performance level and exactly evaluate the seismic performance of buildings. Pushover analysis of fast becoming an accepted method for the seismic evaluation of building structures. The popularity of this approximate, nonlinear static analysis method is due to its conceptual simplicity and ability to graphically describe a capacity and demand of structure. However, some of the shortcomings of the pushover analysis, especially for longer period and irregular buildings, is the inability of method to identify failure mechanisms due to effects of higher modes. In this paper proposed lateral load pattern which includes the contribution of higher modes of vibration for irregular building structure and compared to seismic response obtained by time history.

• Earthquakes and Structures
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• 제5권6호
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• pp.625-655
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• 2013

This paper investigated the seismic behaviour of an innovated non-ductile precast concrete wall structural system; namely HC Precast System (HCPS). The system comprises load-bearing precast wall panels merely connected only to column at both ends. Such study is needed because there is limited research information available in design codes for such structure particularly in regions having low to moderate seismicity threats. Experimentally calibrated numerical model of the wall system was used to carry out nonlinear pushover analyses with various types of lateral loading patterns. Effects of laterally applied single point load (SPL), uniformly distributed load (UDL), modal distributed load (MDL) and triangular distributed load (TDL) onto global behaviour of HCPS were identified. Discussion was focused on structural performance such as ductility, deformability, and effective stiffness of the wall system. Thus, a new method for engineers to estimate the nonlinear deformation of HCPS through linear analysis was proposed.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.71-78
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• 2005

In performance-based design methods, it is clear that the evaluation of the nonlinear response is required. The methods available to the design engineer today are nonlinear tim history analyses, or monotonic static nonlinear analyses, or equivalent static analyses with simulated inelastic influences. The nonlinear time analysis is the most accurate method in computing the nonlinear response of structures, but it is time-consuming and necessitate more efforts. Some codes proposed the capacity spectrum method based on the nonlinear static analysis to determine earthquake-induced demand given the structure pushover curve. This procedure is conceptually simple but iterative and time consuming with some errors. The nonlinear direct spectrum method is proposed and studied to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis. The purpose of this paper is to compare the accuracy and the reliability of approximate nonlinear methods with respect to RC dual system and various earthquakes.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.349-356
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• 2002

There has been an increasing trend toward the use of pushover analysis as a tool for evaluating the seismic resistant and safety of a building structure in the performance based earthquake engineering field. The ATC-40 document proposed a nonlinear static procedure based on the Capacity Spectrum Method to determine earthquake-induced demand given the structure pushover curve, which a curve representing base shear versus roof displacement. However, the procedure is conceptually simple, iterative and time consuming method and may sometimes lead to no solution or multiple solutions. A new improved method of seismic performance evaluation for moment frame building, which take into account the previously mentioned deficiencies of currently used elastic design procedures, is presented in this paper. The results of nonlinear static and nonlinear time history analysis of an example high-rise steel moment frame designed by the proposed method are presented and discussed.

• Structural Engineering and Mechanics
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• 제53권4호
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• pp.745-765
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• 2015

A nonlinear Finite Element (FE) algorithm is proposed to analyze the Reinforced Concrete (RC) columns subjected to Cyclic Loading (CL), Cyclic Oriented Lateral Force and Axial Loading (COLFAL), Monotonic Loading (ML) or Oriented Pushover Force and Axial Loading (OPFAL) in any direction. In the proposed algorithm, the following parameters are considered: uniaxial behavior of concrete and steel elements, the pseudo-plastic hinge produced in the critical sections, and global behavior of RC columns. In the proposed numerical simulation, the column is discretized into two Macro-Elements (ME) located between the pseudo-plastic hinges at critical sections and the inflection point. The critical sections are discretized into Fixed Rectangular Finite Elements (FRFE) in general cases of CL, COLFAL or ML and are discretized into Variable Oblique Finite Elements (VOFE) in the particular cases of ML or OPFAL. For pushover particular case, a fairly fast converging and properly accurate nonlinear simulation method is proposed to assess the behavior of RC columns. The proposed algorithm has been validated by the results of tests carried out on full-scale RC columns.

• 복합신소재구조학회 논문집
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• 제4권4호
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• pp.9-14
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• 2013

In this study, flexural strength properties of SC shear walls were investigated through static pushover test. Failure modes and stiffness characteristics of SC shear walls under lateral loads were inspected by analyzing the experimental results. Main failures of unstiffened SC shear walls were found to be the type of bending shear failure due to the unbonding of the steel plate at the concrete interface. The ductility capacity of SC structures was also confirmed to be improved, which is considered to be a confining effect on steel plates in the longitudinal behavior of SC shear walls.

• Earthquakes and Structures
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• 제12권6호
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• pp.591-601
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• 2017

To prevent or limit the damage caused by earthquakes on existing buildings, several retrofitting techniques are possible. In this work, an ultra high performance concrete based on sand dune has been formulated for use in the reinforcement of a multifunctional tower in the city of Skikda in Algeria. Tests on the formulated ultra high performance concrete are performed to determine its characteristics. A nonlinear dynamic analysis, based on the "Pushover" method was conducted. The analysis allowed an optimization of the width of reinforced concrete walls used in seismic strengthening. Two types of concrete are studied, the ordinary concrete and the ultra high performance concrete. Both alternatives are compared with the reinforcement with carbon fibers and by base isolation retrofit design.

• Steel and Composite Structures
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• 제27권5호
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• pp.613-622
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• 2018

The requirement to safe and economical buildings caused to the exploitation of nonlinear capacity structures and optimization of them. This requirement leads to forming seismic design method based on performance. In this study, concentrically braced frames (CBFs) have been optimized at the immediate occupancy (IO) and collapse prevention (CP) levels. Minimizing structural weight is taken as objective function subjected to performance constraints on inter-story drift ratios at various performance levels. In order to evaluate the seismic capacity of the CBFs, pushover analysis is conducted, and the process of optimization has been done by using Bee Algorithm. Results indicate that performance based design caused to have minimum structural weight and due to increase capacity of CBFs.

• Steel and Composite Structures
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• 제13권1호
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• pp.35-46
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• 2012

Implementation of openings in beams web has been introduced as an innovative method for improving seismic performance of steel moment frames. In this paper, several steel moment frames have been studied in order to evaluate the effect of openings in beams web. The beam sections with web opening have been modeled as a simplified super-element to be used in designing frames and to determine opening configurations. Finite element models of designed frames were generated and nonlinear static pushover analysis was conducted. The efficient location for openings along the beam length was discovered and the effects of beams with web openings on local and global behavioral characteristics of frames were discussed. Base on the results, seismic performance of steel moment frames was improved by creating openings in beams web, in terms of reduction in stress level of frame sensitive areas such as beam to column connections and panel zones.