scholarly journals Influence of Multiple-Support Excitation on Seismic Response of Reinforced Concrete Arch Bridges

2019 ◽  
Vol 10 (1) ◽  
pp. 17 ◽  
Author(s):  
Marta Savor Novak ◽  
Damir Lazarevic ◽  
Josip Atalic ◽  
Mario Uros
Keyword(s):  
Reinforced Concrete ◽  
Spatial Variation ◽  
Seismic Response ◽  
Ground Motion ◽  
Seismic Analysis ◽  
Numerical Study ◽  
Relative Significance ◽  
Multiple Support ◽  
Arch Bridges ◽  
Support Excitation

Although post-earthquake observations identified spatial variation of ground motion (i.e., multiple-support excitation) as a frequent cause of the unfavorable response of long-span bridges, this phenomenon is often not taken into account in seismic design to simplify the calculation procedure. This study investigates the influence of multiple-support excitation accounting for coherency loss and wave-passage effects on the seismic response of reinforced concrete deck arch bridges of long spans founded on rock sites. Parametric numerical study was conducted using the time-history method, the response spectrum method, and a simplified procedure according to the European seismic standards. Results showed that multiple-support excitation had a detrimental influence on response of almost all analyzed bridges regardless of considered arch span. Both considered spatial variation effects, acting separately or simultaneously, proved to be very important, with their relative significance depending on the response values and arch locations analyzed and seismic records used. Therefore, it is suggested that all spatially variable ground-motion effects are taken into account in seismic analysis of similar bridges.

Seismic Analysis of Reinforced Concrete Rib Arch Bridge

2012 ◽  
Vol 256-259 ◽  
pp. 1496-1502 ◽  
Author(s):  
Da Lin Hu ◽  
Tian Qi Qu ◽  
Hong Bin Wang ◽  
Long Gang Chen
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Ground Motion ◽  
Seismic Analysis ◽  
Element Model ◽  
Structural Dynamic ◽  
Arch Bridge ◽  
Internal Forces ◽  
Arch Bridges ◽  
Horizontal Ground Motion

There are few researches on seismic response of reinforced concrete rib arch bridges at present; therefore, it is necessary to analyze seismic performance of this kind of bridges. Based on the engineering background of a three-span reinforced concrete rib arch bridge, a full bridge finite element model is built to analyze the structural dynamic characteristic and seismic response of the bridge. The internal forces and displacements of each key section is compared and discussed when the bridge is excited by horizontal unidirectional ground motion or the combination of vertical and horizontal ground motion. The structural seismic response calculated with different analysis methods is compared. The research results of this study can be used as a reference for the seismic design of similar bridges.

scholarly journals Effect of Frequency Content of Earthquake on the Seismic Response of Interconnected Electrical Equipment

CivilEng ◽  
2020 ◽  
Vol 1 (3) ◽  
pp. 198-215
Author(s):  
Kashif Salman ◽  
Sung Gook Cho
Keyword(s):  
Seismic Response ◽  
Natural Frequency ◽  
Ground Motion ◽  
High Frequency ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Low Frequency ◽  
Stable Operation ◽  
Design Spectrum ◽  
Standard Design

To ensure the stable operation of safety-related nuclear power plant (NPP) equipment, they are tested by following the seismic qualification procedures. The in-cabinet response spectrum (ICRS) is used to test the mounted components. However, the ICRS varies significantly with the number of uncertainties that include (1) loaded and unloaded condition of the cabinets, (2) the number of connected cabinets (grouping effects), and (3) higher frequency contents in the seismic inputs. This study focuses on the ICRS generation and alteration induced due to the listed uncertainties. A prototype of an electrical cabinet was experimentally examined. Followed by the numerical modeling of the cabinet, the seismic analysis for the group of cabinets was performed using artificial ground motion compatible with the standard design spectrum and the real accelerograms of high and low frequency contents. The seismic response using finite element (FE) analysis manifests (1) natural frequency of loaded cabinets reduced due to the in-cabinet components while for the unloaded cabinets it increased significantly, (2) a consistent reduction in ICRS due to the grouping effect was recorded when excited by the lower-frequency motion, while it was amplified dramatically due to high-frequency pulses. Interconnected cabinets under the low-frequency input motions have a significant reduction of 50% in the ICRS that corresponds to the higher stiffness of the cabinets, while a 100% increase under the high frequency of ground motion was obtained. High frequency of ground motion, usually above 10 Hz, can cause the interconnected cabinets to resonate as the natural frequency of these equipment lies in this range.

The Seismic Response Analysis Method of the Jacket under Multiple Support Excitation

2012 ◽  
Vol 256-259 ◽  
pp. 2051-2055
Author(s):  
Jian Mei Sun ◽  
Hao Cui
Keyword(s):  
Seismic Analysis ◽  
Response Analysis ◽  
Analysis Method ◽  
Seismic Response Analysis ◽  
Oil Reserves ◽  
Long Span ◽  
Simplified Method ◽  
Multiple Support ◽  
Support Excitation ◽  
Offshore Oil

With the development of demand of exploiting offshore oil reserves, the Jacket platform structure’ span and depth is more and more large, so the seismic analysis of the jacket structure will become more and more complicated. In the dynamic analysis of long-span structures, multiple support excitation may be accounted is necessary. For big jacket structure, it is more accurate and reasonable by multiple support excitation than by uniform excitation. The objective of the research described herein is to develop a simplified method to investigate the effect of multiple support excitation on the jacket structure.

Study on Ground Motion Intensities and Modification for Seismic Analysis of Reinforced Concrete Frames

2014 ◽  
Vol 1065-1069 ◽  
pp. 1438-1442
Author(s):  
Dong An ◽  
Tie Jun Qu
Keyword(s):  
Reinforced Concrete ◽  
Ground Motion ◽  
Nonlinear Dynamic ◽  
Seismic Analysis ◽  
Reinforced Concrete Buildings ◽  
Intensity Measure ◽  
Concrete Buildings ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses ◽  
Spectrum Matching

The selection of input ground motion for seismic analysis of the structure is a complicated task, especially when nonlinear dynamic analysis is utilized. A decision has to be made regarding the intensity measure better to represent the potential damage of the ground motion. This paper presents a lot of analysis to deal with the problem. A set of nonlinear dynamic analyses were conducted on reinforced concrete buildings widely present in China. Input ground motions contain uncertainty and variability comes from both natural recordings and synthetic data. First, a set of natural recordings is considered. Second, two ground motion modification schemes are used in this study: magnitude scaling and spectrum matching. Third, a set of ground motion is synthesized. The peak value of displacement has been selected as the response parameter better able to represent the structural damage level. Nonlinear dynamic analyses of reinforced concrete buildings simulated by OpenSEES are carried out to evaluate the correlation coefficients of displacement response and the chosen ground motion parameters. Findings from the investigation indicate that the Housner intensity is the more effective intensity measure for selecting the seismic input. The synthesized ground motion fit with code spectrum shows good performance as a design input motion. Considering ground motion modification, spectrum matching is generally more stable in response prediction than scaling.

Seismic Performance Analysis of Tower Lines System under Multiple Support Excitation

2013 ◽  
Vol 732-733 ◽  
pp. 1085-1089
Author(s):  
Jian Mei Sun ◽  
Jun Qiang Li ◽  
Fu Gang Yang
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
Time History ◽  
Time History Analysis ◽  
Transmission Tower ◽  
Long Span ◽  
History Analysis ◽  
Tower Structure ◽  
Multiple Support ◽  
Support Excitation

In order to determine the calculational model of long span transmission tower structure under the multiple support excitation, tower-lines system are adopted. Seismic Performance of long span transmission tower lines system under Multiple Support Excitation were studied by time history analysis method. The seismic response difference of two kinds of excitation is analyzed from Dynamic Characteristics and the number of dangerous bar. It will offer the theory data for the seismic design of the kind of structure. Through analysis, the seismic response difference of the two kinds excitation is correlative to the apparent velocity; Therefore long span transmission tower structure should be considered the effect of multiple support excitation, otherwise the conclusion will be inclined to conservative or risk. Key words: tower lines system; seismic response; time history analysis,multiple support excitation

scholarly journals Study of the Seismic Response on the Infill Masonry Walls of a 15-Storey Reinforced Concrete Structure in Nepal

Buildings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 39 ◽  
Author(s):  
André Furtado ◽  
Nelson Vila-Pouca ◽  
Humberto Varum ◽  
António Arêde
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Concrete Structure ◽  
Numerical Study ◽  
Numerical Models ◽  
Ambient Vibration ◽  
Reinforced Concrete Structure ◽  
Infill Walls ◽  
Ambient Vibration Tests ◽  
Vibration Tests

Following the strong earthquake on April 25, 2015 in Nepal, a team from the University of Porto, in collaboration with other international institutions, made a field study on some of the most affected areas in the capital region of Kathmandu. One of the tasks was the study of a high-rise settle of buildings that were damaged following the earthquake sequence. A survey damage assessment was performed to a 15-storey infilled reinforced concrete structure, which will be detailed in the manuscript. Moreover, ambient vibration tests were carried out to determine the natural frequencies and corresponding vibration modes of the structure. The main aim of this manuscript is to present a numerical study concerning the influence of the masonry infill walls in the structure seismic response. For this, three numerical models were built discriminating the situations with and without damage and nondamaged infill walls. Validation and calibration of the numerical model was ensured by comparing the numerical frequencies with those obtained from ambient vibration tests. In addition, linear elastic analyses were carried out, using real accelerograms from the Gorkha earthquake to assess and quantify the major differences between the models in terms of inter-storey drifts ratios, inter-storey shear forces and seismic loadings.

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