Seismic behavior of RC building with and without buckling restrained braces / Daniel Rumbi Teruna (original) (raw)

Seismic Behavior of RC Building with and Without Buckling Restrained Braces

Journal of Mechanical Engineering, 2019

Nonlinear analysis for evaluating seismic performance of building under seismic excitation requires nonlinear properties of any component that are quantified by strength and deformation capacities. The nonlinear behavior of beams and column components are modeled in the form of plastic hinges as described in ASCE41-13 [1] guideline. This document provides the hinge rotation capacity for several ranges of detailing assumption. Buckling restrained braces (BRB) can be modeled as a link element with forcedeformation behavior through Wen's plasticity model. This paper evaluates possible differences of seismic performance of six-story reinforced concrete moment resisting frame with conforming and non-conforming plastic hinge rotation, with and without BRB in placed. The nonlinear static analysis is performed to obtain capacity curve using inverted triangular load pattern as described in ASCE7-10 [2]. The behaviors of investigating frames are discussed and evaluated by means of capacity curves and plastic hinge formation mechanism. Moreover, nonlinear time history analysis is carried out to investigate the effect of BRB properties on the seismic behavior of building model subjected to selected ground motion records. Furthermore, response parameters of building model are presented and compared in the form of base shear, story displacement, and story drift.

Seismic responses comparison of RC building in consideration of plastic hinge models and properties

IOP Conference Series: Materials Science and Engineering

Assessment of reinforced concrete building capacity under seismic excitation has been recognized to be highly important for the past decades especially in Indonesia. Previous studies showed failures of RC building occurred in columns with bad confinement. The confinement in RC column has significant role in providing ductility and shear capacity for seismic loads. For this aim, a five-story RC building having different confinement on column members are investigated under seismic excitation. Three set of ground motions are selected and matched with target response spectrum of Indonesian code. Nonlinear analysis is performed by utilizing OpenSEES finite element software. To account the inelastic behaviour of beam and column elements, two types of plastic hinge are applied for both elements, namely finite length plastic hinges (plastic zone) and distributed hinges along the length of elements. The results show that there is a noticeable difference in seismic responses in correlation with the building model.

Seismic Analysis of Building Structure with Buckling Restrained Brace

Conventional braces have limited deformation ductility capacity, and exhibit unsymmetrical hysteretic cycles, with marked strength deterioration when loaded in compression. To overcome the above mentioned problems, a new type of brace was developed in Japan called as buckling restrained braces, designated as BRB's. These braces are designed such that buckling is inhibited to occur, exhibiting adequate behavior and symmetrical hysteretic curves under the action of both tensile and compressive cycles, produced by the action of seismic and wind forces. Nonlinear time history analysis, response spectrum method and pushover analysis of 10-story 2D frame is carried using software, ETAB. The response parameters used to evaluate structural performance are natural time period, story displacement, inter story drift, story shear and axial forces.

Improving the Seismic Response of Tall Reinforced Concrete Buildings Using Buckling Restrained Braces

In the last years BRB were used in existing structures and in new ones as primary lateral force resisting elements. Retrofit of existing buildings in seismic areas can be made by using buckling restrained braces (BRBs), because they have the ability to sustain large inelastic deformations without important loss of strength. This study analyzes the possibility of using BRBs to improve the seismic response of tall reinforced concrete buildings. Therefore dynamic nonlinear analysis was performed on two tall structures: first, one structure with reinforced concrete walls (that has been designed according to the Romanian Seismic Design Code) and then the same structure with buckling restrained braces included. Computation was made for three recorded accelerograms. The aim of the study was to highlight the advantages and disadvantages of using BRBs together with reinforced concrete walls for improving the seismic response of tall buildings. Parameters like natural period, deformations and stresses were carefully evaluated and then some comparatively studies were made in order to establish the efficiency of the buckling restrained braces.

IRJET-SEISMIC ANALYSIS OF BUILDING STRUCTURE WITH BUCKLING RESTRAINED BRACE

Conventional braces have limited deformation ductility capacity, and exhibit unsymmetrical hysteretic cycles, with marked strength deterioration when loaded in compression. To overcome the above mentioned problems, a new type of brace was developed in Japan called as buckling restrained braces, designated as BRB’s. These braces are designed such that buckling is inhibited to occur, exhibiting adequate behavior and symmetrical hysteretic curves under the action of both tensile and compressive cycles, produced by the action of seismic and wind forces. Nonlinear time history analysis, response spectrum method and pushover analysis of 10-story 2D frame is carried using software, ETAB. The response parameters used to evaluate structural performance are natural time period, story displacement, inter story drift, story shear and axial forces.

Upgrading the seismic capacity of existing RC buildings using buckling restrained braces

Alexandria Engineering Journal, 2017

Many existing RC buildings do not meet the lateral strength requirements of current seismic codes and are vulnerable to significant damage or collapse in the event of future earthquakes. In the past few decades, buckling-restrained braces have become increasingly popular as a lateral force resisting system because of their capability of improving the strength, the stiffness and the energy absorbing capacity of structures. This study evaluates the seismic upgrading of a 6-story RCbuilding using single diagonal buckling restrained braces. Seismic evaluation in this study has been carried out by static pushover analysis and time history earthquake analysis. Ten ground motions with different PGA levels are used in the analysis. The mean plus one standard deviation values of the roof-drift ratio, the maximum story drift ratio, the brace ductility factors and the member strain responses are used as the basis for the seismic performance evaluations. The results obtained in this study indicate that strengthening of RC buildings with buckling restrained braces is an efficient technique as it significantly increases the PGA capacity of the RC buildings. The results also indicate the increase in the PGA capacity of the RC building with the increase in the amount of the braces.

Seismic performance and vulnerability analysis of code: conforming RC buildings

2011

This paper investigates seismic performance and vulnerability analysis of 4-storey and 6-storey code-conforming (IS: 456-2000, Indian standard for plain and reinforced concrete code and IS: 1893-2002, Indian standard criteria for earthquake resistant design of structures) reinforced concrete (RC) buildings. The buildings are designed for two different cases such as ordinary moment resisting frame (OMRF) and special moment resisting frame (SMRF). The nonlinear static analysis (pushover analysis) is used to capture initial yielding and gradual progressive plastic behaviour of elements and overall building response under seismic excitations. The deformation characteristics of structural elements are essential to simulate the plastic hinge formation in the process of generation of capacity curve during the pushover analysis. An analytical procedure is developed to evaluate the yield, plastic and ultimate rotation capacities of beams and columns along with different plastic hinge lengths...

Seismic performance evaluation of existing RC buildings designed as per past codes of practice

Sadhana, 2012

Assessing the capacity of existing building as per the present codes of practice is an important task in performance-based evaluation. In order to enhance the performance of existing buildings to the present level of ductile design prescribed by present codes and find the retrofit or design a rehabilitation system, there is an urgent need to assess accurately the actual lateral load resistance and the potential failure modes. In this paper, a typical 6-storey reinforced concrete (RC) building frame is designed for four design cases as per the provisions in three revisions of IS: 1893 and IS: 456 and it is analysed using user-defined (UD) nonlinear hinge properties or default-hinge (DF) properties, given in SAP 2000 based on the FEMA-356 and ATC-40 guidelines. An analytical procedure is developed to evaluate the yield, plastic and ultimate rotation capacities of RC elements of the framed buildings and these details are used to define user-defined inelastic effect of hinge for columns as P-M-M and for beams as M3 curves. A simplified three parameter model is used to find the stress-strain curves of RC elements beyond the post yield region of confined concrete. Building performance of structural components in terms of target building performance levels are studied with the nonlinear static analysis. The possible differences in the results of pushover analysis due to default-and user-defined nonlinear component properties at different performance levels of the building are studied.

Guidelines for Nonlinear Structural Analysis for Design of Buildings Part IIb – Reinforced Concrete Moment Frames

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SEISMIC EVALUATION OF R/C FRAMED BUILDING USING SHEAR FAILURE MODEL

KEYWORDS: shear hinges, shear strength, shear displacement, nonlinear static pushover analysis, hinge property, reinforced concrete. Prediction of nonlinear shear hinge parameters in RC members is difficult because it involves a number of parameters like shear capacity, shear displacement, shear stiffness. As shear failure are brittle in nature, designer must ensure that shear failure can never occur. Designer has to design the sections such that flexural failure (ductile mode of failure) precedes the shear failure. Also design code does not permit shear failure. However, past earthquakes reveal that majority of the reinforced concrete (RC) structures failed due to shear. Indian construction practice does not guaranty safety against shear. Therefore accurate modelling of shear failure is almost certain for seismic evaluation of RC framed building. A thorough literature review does not reveal any information about the nonlinear modelling of RC sections in Shear. The current industry practice is to do nonlinear analysis for flexure only. Therefore, the primary objective of the present work is to develop nonlinear forcedeformation model for reinforced concrete section for shear and demonstrate the importance of modelling shear hinge in seismic evaluation of RC framed building. From the existing literature it is found that equations given in Indian Standard IS-456: 2000 and American Standard ACI-318: 2008 represent good estimate of ultimate strength. However, FEMA-356 recommends ignoring concrete contribution in shear strength calculation for ductile beam under earthquake loading. No clarity is found regarding yield strength from the literature. Priestley et al. (1996) is reported to be most effective for calculating shear displacement at iii yield whereas model proposed by Park and Paulay (1975) is most effective in predicting the ultimate shear displacements for beams and columns. Combining these models shear hinge properties can be calculated. To demonstrate the importance of modelling shear hinges, an existing RC framed building is selected. Two building models, one with shear hinge and other without shear hinges, are analysed using nonlinear static (pushover) analysis. This study found that modelling shear hinges is necessary to correctly evaluate strength and ductility of the building. When analysis ignores shear failure model it overestimates the base shear and roof displacement capacity of the building. The results obtained here show that the presence of shear hinge can correctly reveal the non-ductile failure mode of the building. iv