Torsional provisions in building codes

1982 ◽  
Vol 9 (1) ◽  
pp. 38-46 ◽  
Author(s):  
W. K. Tso ◽  
V. Meng
Keyword(s):  
Response Spectrum ◽  
Building Codes ◽  
Irregular Structures ◽  
Uniform Frame ◽  
Reliable Procedure ◽  
Lateral Resonance ◽  
Story Building ◽  
Current Code ◽  
Code Provisions ◽  
Computed Torque

A study is made of the accuracy of the static code provisions on torsional effects, with special reference to the National Building Code of Canada of 1977. A uniform frame type monosymmetric 12-story building is used as an example. The static story torque is compared with the dynamic torque computed using the response spectrum technique as outlined in Commentary K of the Code. It has been found that for a building with uniform eccentricity, the static code torque estimate is good if the effect of sympathetic coupled torsional–lateral resonance is small. At the sympathetic coupled resonance, the static code torsional provision underestimates the story torque by a factor of approximately two. Also, it is shown that for buildings with large eccentricities, sympathetic resonance is unlikely to occur and the current Code requirement of doubling the computed torque for design is a very conservative requirement.In addition, the eccentricity expression given in the 1980 Code is used to estimate the story torques for eccentrically set-back buildings and its accuracy is checked with a response spectrum technique. It is concluded that for irregular structures, such as eccentrically set-back buildings, a dynamic analysis is the only reliable procedure for the estimation of the torque loading on the building.

Seismic assessment of existing RC shear walls non-compliant with current code provisions

2013 ◽  
Vol 65 (17) ◽  
pp. 1059-1072 ◽  
Author(s):  
Konstantinos Christidis ◽  
Emmanouil Vougioukas ◽  
Konstantinos G. Trezos
Keyword(s):  
Shear Walls ◽  
Seismic Assessment ◽  
Current Code ◽  
Code Provisions

scholarly journals A Literature Review on Seismic Response of Floating Column Building

2021 ◽  
Vol 9 (12) ◽  
pp. 68-72
Author(s):  
Deepak Jain
Keyword(s):  
Literature Review ◽  
Seismic Response ◽  
Spectrum Analysis ◽  
Response Spectrum ◽  
Seismic Loads ◽  
Seismic Zone ◽  
Response Spectrum Analysis ◽  
Promising Solution ◽  
Story Building ◽  
Shape And Size

Abstract: Floating column building is a new fascination for engineers. As floating column buildings provides more space and good aesthetics to the building. But have high structural challenges, when a floating column is provided in a multi-story building in a high seismic zone. This paper reviews several studies conducted on the floating column building and its behavior under seismic loads. This paper studies that floating column building are vulnerable to the high seismic zones. The risk of damage also depends on the shape and size of the buildings.The ductile detailing of the joints is the promising solution for immediate failure of such buildings. Keywords: Floating Column, Response spectrum analysis. Vulnerable, damage, multi-story

A Comparative Study of Seismic Performance Defined by Chinese Code and Eurocode8 on Seismic Design of Bridges

2011 ◽  
Vol 90-93 ◽  
pp. 3108-3116
Author(s):  
Ben Yan Lu ◽  
Gang Wang
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Highway Bridges ◽  
Lessons Learned ◽  
Performance Criteria ◽  
Existing Problems ◽  
Performance Based Seismic Design ◽  
Earthquake Action ◽  
Ground Types ◽  
Current Code

Earthquake codes have been revised and updated in recent years. The issue and implementation of the guidelines for seismic design of bridges have attracted interests and attentions of many researchs at home and abroad. The most important aspect of the code rests on its main approach incorporating “performance-based seismic design”. The main purpose of this study is to investigate the differences caused by the use of guidelines for seismic design of highway bridges and Eurocode8 for bridges in performance criteria, seismic design categories, ground types, response spectrum, earthquake action and detailing of ductile piers. The differences in expressions and some important points for performance criteria, seismic design categories, ground types, response spectrum, earthquake action and detailing of ductile piers by codes are briefly illustrated in tables and figures. Based on the lessons learned from significant earthquakes in the last few years, the existing problems of the current code are pointed, and the trends of future study are discussed.

Comparison and Research on Seismic Performance between Guidelines for Seismic Design of Highway Bridges and Eurocode 8 for Seismic Design of Bridges

2010 ◽  
Vol 163-167 ◽  
pp. 4395-4400
Author(s):  
Ben Yan Lu ◽  
Bo Quan Liu ◽  
Ming Liu ◽  
Guo Hua Xing
Keyword(s):  
Seismic Design ◽  
Future Study ◽  
Response Spectrum ◽  
Highway Bridges ◽  
Lessons Learned ◽  
Performance Criteria ◽  
Eurocode 8 ◽  
Existing Problems ◽  
Earthquake Action ◽  
Current Code

Earthquake codes have been revised and updated in recent years. The issue and implementation of the guidelines for seismic design of bridges have attracted interests and attentions of many researchs at home and abroad. In this paper, it is compared that the provisions about performance criteria, seismic design categories, response spectrum and earthquake action between guidelines for seismic design of highway bridges and Eurocode 8 for bridges. The main purpose of this study is to investigate the differences caused by the two codes in performance criteria, seismic design categories, response spectrum and earthquake action. The results indicate that it is similar in performance criteria, seismic design categories and response spectrum between guidelines for seismic design of highway bridges and Eurocode 8 for bridges. Based on the lessons learned from significant earthquakes in the last few years, the existing problems of the current code are pointed, and the trends of future study are discussed.

Seismic Response of Vertical Irregular Structures in Setback and Stepped Buildings

2021 ◽  
Vol 2 (1) ◽  
pp. 15-25
Author(s):  
Surendra Bhatta ◽  
Latip Kumar Sharma ◽  
Bharat Niure ◽  
Sudhir Niraula
Keyword(s):  
Seismic Vulnerability ◽  
Response Spectrum ◽  
Plastic Hinge ◽  
Pushover Analysis ◽  
Poor Performance ◽  
Finite Element Software ◽  
Reconnaissance Survey ◽  
Irregular Structure ◽  
Irregular Structures ◽  
Formation Pattern

Vertical irregular buildings are frequently constructed across the globe for functional as well as aesthetic purpose. However post-earthquake reconnaissance survey reports revealed high seismic vulnerability of the building with vertical irregularities. Consequently it is very important to explore the reason behind the high seismic vulnerability and the poor performance of irregular structures during the earthquake. A humble effort is under taken considering several case studies comprising different configuration of vertical irregular structures, so as to comprehend the seismic behavior of vertical irregular structure using response spectrum and pushover analysis has been attempted in finite element software ETABS 16.2.1 version. The results of the analysis indicate the irregular structures have ample chance of higher stress concentration as well as higher displacement demand at the vicinity of irregularity. Member strength enhancement at the vicinity of vertical irregularity may improve the overall seismic performance of the building. Also, this research checks the adequacy of fundamental mode properties for the quantification of vertical irregularity. Furthermore, pushover analysis has been done to observe the hinge formation pattern and also the plastic hinge rotation for observing the performance level of building.

Seismic Behavior of Horizontally Irregular Structures: Current Wisdom and Challenges Ahead

2016 ◽  
Vol 68 (6) ◽  
Author(s):  
Suvonkar Chakroborty ◽  
Rana Roy
Keyword(s):  
Seismic Behavior ◽  
Ground Motions ◽  
Response Assessment ◽  
Design Guidelines ◽  
Research Progress ◽  
Future Research ◽  
Irregular Structures ◽  
Traditional Design ◽  
The Subject ◽  
Code Provisions

In view of the stronger vulnerability of horizontally irregular structures during earthquakes, numerous studies have been made since mid-1950 s. Unfortunately, research progress in this subject does not appear encouraging. This is evident from the current wisdom embodied in modern codes in the form of design guidelines. Beginning with a critical review of the earlier works and the available code-provisions, the present paper emphasizes on the prevalent controversies and the fundamental fallacies in research studies and traditional design. The review intends to address the strength vis-a-vis weakness of the studies accomplished so far and helps streamlining future research. The present paper also summarizes the updated views for selecting and processing appropriate set of ground motions. This is a key input in seismic response assessment and a major reason of the existing controversies in the subject of asymmetry. A prognostic scrutiny of the research progress recognizes the prospective challenges ahead.

Application of Supplemental Damping Characteristics to Response Spectrum Analyses of Nonproportionally Damped Multistory Asymmetric-Plan Buildings

2013 ◽  
Vol 29 (1) ◽  
pp. 207-232 ◽  
Author(s):  
Jui-Liang Lin ◽  
Keh-Chyuan Tsai
Keyword(s):  
Response Spectrum ◽  
Response Spectra ◽  
Vibration Modes ◽  
Numerical Examples ◽  
System Parameters ◽  
Damping Characteristics ◽  
Supplemental Damping ◽  
Story Building

For practicing engineers, knowledge of the characteristics of supplemental damping in buildings is essential to understand the resultant effects of added damping. Characterizing the overall system parameters representing the amount and the plan-wise distribution of the supplemental damping in a single-story asymmetrical building is straightforward. However, this becomes a difficult task for multistory asymmetrical buildings. For this reason, this paper first develops the effective one-story building (EOSB), which retains the characteristics of the two dominant vibration modes of the original nonproportionally damped multistory asymmetrical building. By using the EOSB, it becomes convenient to characterize the supplemental damping in the original multistory asymmetrical building. The effectiveness of this approach is verified by using three numerical examples, which include one one-story, three eight-story, and one 20-story asymmetrical buildings. Next, the relationships between the roof displacements of the original building and those of the EOSB are established. This enables the application of the response spectra constructed from the EOSBs to estimate the peak roof displacements of the original multistory asymmetrical building.

Strength Demand Issues Relevant for the Seismic Design of Moment-Resisting Frames

2005 ◽  
Vol 21 (2) ◽  
pp. 415-439 ◽  
Author(s):  
Ricardo A. Medina ◽  
Helmut Krawinkler
Keyword(s):  
Seismic Design ◽  
Brittle Failure ◽  
Failure Modes ◽  
Shear Forces ◽  
Moment Resisting Frames ◽  
Weak Beam ◽  
Moment Resisting ◽  
Nonlinear Static ◽  
Current Code ◽  
Code Provisions

This paper deals with the evaluation of strength demands relevant for the seismic design of columns that are part of moment-resisting frames. Regular frames with fundamental periods from 0.3 sec. to 3.6 sec. and number of stories from 3 to 18 are investigated. An evaluation of the relationships between strength demands (e.g., story shear forces, story overturning moments, and moments in columns), ground motion intensity, fundamental period, and number of stories is the focus of this paper. The results from this study demonstrate that the magnitude and distribution over the height of maximum axial and shear forces in columns exposed to severe earthquakes often are not adequately estimated by current seismic design and analysis procedures (e.g., the nonlinear static pushover). Moreover, the potential of plastic hinging in columns is high for regular frames designed according to the strong-column/weak-beam requirements of current code provisions, and more stringent strong-column/weak-beam criteria appear to be called for. The presented results are intended to provide guidance for improvement of seismic design provisions to avoid brittle failure modes in columns of moment-resisting frames.

Seismic demand of moderately ductile reinforced concrete shear walls subjected to high-frequency ground motions

2014 ◽  
Vol 41 (2) ◽  
pp. 125-135 ◽  
Author(s):  
Hieu Luu ◽  
Pierre Léger ◽  
Robert Tremblay
Keyword(s):  
Reinforced Concrete ◽  
High Frequency ◽  
Shear Force ◽  
Shaking Table Test ◽  
Numerical Models ◽  
Response Spectrum ◽  
Shear Walls ◽  
Shaking Table ◽  
Seismic Force ◽  
Code Provisions

A parametric study was performed to examine the seismic behaviour of moderately ductile (MD) reinforced concrete shear walls designed according to Canadian code provisions, including National Building Code of Canada (NBCC) 2010 and Canadian Standards Association (CSA) 23.3-04, when subjected to typical high-frequency eastern North America earthquakes. The numerical models were experimentally validated based on large specimens shaking table test results. The results obtained following the code response spectrum procedure were compared with the results from inelastic response history analyses to investigate the effect of higher modes on seismic force demands. The results indicate that current code provisions for MD shear walls need to be modified. A new base shear factor and shear force design envelop are proposed to evaluate the seismic shear force demand more realistically. This study also recommends that the current CSA 23.3-04 requirements for ductile shear walls for bending moments could be applied to constrain the location of inelastic flexural deformations at the base of MD shear walls.

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