Prediction of floor responses to crowd bouncing loads by response reduction factor and spectrum method

2020 ◽  
pp. 136943322097556
Author(s):  
Jun Chen ◽  
Jingya Ren ◽  
Vitomir Racic
Keyword(s):  
Structural Damage ◽  
Response Spectrum ◽  
Field Measurements ◽  
Reduction Factor ◽  
Response Reduction Factor ◽  
Long Span ◽  
Single Person ◽  
Vibration Serviceability ◽  
Concert Halls ◽  
Structural Responses

Bouncing is a typical rhythmic crowd activity in entertaining venues, such as concert halls and stadia. When the activity’s frequency is close to the natural frequency of the occupied structure, the corresponding bouncing loads can cause intense structural vibrations resulting in vibration serviceability problems, even structural damage. This study suggests a method for prediction of vibration response due to crowd bouncing by a response reduction factor (RRF) in conjunction with a previously established response spectrum approach pertinent to a single person bouncing. The RRF is defined as a ratio between structural responses with and without taking into account synchronization of body movements of individuals in a bouncing crowd. The variations of RRF with number of persons, structural frequency, bouncing frequency and structural damping ratios have been studied using experimental records of crowd bouncing loads. Based on the findings a practical design curve for RRF has been proposed. Application of the proposed method has been validated on numerical simulations and field measurements of a long-span floor subjected to crowd bouncing loads.

A Load Combination Method for Aseismic Design of Multiple Supported Piping Systems

1989 ◽  
Vol 111 (1) ◽  
pp. 10-16 ◽  
Author(s):  
K. Suzuki ◽  
A. Sone
Keyword(s):  
Structural Model ◽  
Response Spectrum ◽  
Reduction Factor ◽  
Combination Method ◽  
Piping System ◽  
Response Reduction Factor ◽  
Load Combination ◽  
Combination Scheme ◽  
Piping Systems ◽  
Reduction Effect

A new load combination scheme for seismic response calculation of piping systems subjected to multiple support excitations is presented. This scheme has an advantage, such that the cross-correlation among support excitations are properly taken into account by use of a stationary random vibration approach. The authors also present the idea of generating a “multi-excitation floor response spectrum.” First, using a simple analytical SDOF piping system to two support excitations and a simple Z-shaped piping model for shaking test, the combination law is supplied to various correlation cases of two support excitations and the maximum responses of piping in a fundamental mode is calculated. Second, nonlinear characteristics such as gap and friction appearing between piping itself and supports are specifically investigated. The response effect due to these nonlinearities is evaluated by the results through the shaking test with a piping-support structural model, and the amount of response reduction effect is represented by “a response reduction factor β.”

Vibration Serviceability of Long Span Cable Bridges using Long-term Monitoring Data

2019 ◽  
Author(s):  
Eui-seung Hwang ◽  
Sun-Kon Kim ◽  
Do-Young Kim ◽  
Ki-Jung Park
Keyword(s):  
Monitoring Data ◽  
Suspension Bridges ◽  
Span Length ◽  
Bridge Design ◽  
Long Span ◽  
Vibration Serviceability ◽  
Long Term Monitoring ◽  
Deflection Limit ◽  
Term Monitoring

<p>Along with building slender and longer span structures, vibration serviceability becomes more important considerations in bridge design and maintenance. In this study, vibration serviceability and deflection limit for long span cable bridges are investigated using long-term monitoring data such as accelerations and displacements of bridges. Exampled bridges are Yi Sun-Sin Grand Bridge (suspension bridge, main span length=1,545m) and 2<sup>nd</sup> Jindo Grand Bridge (cable stayed bridge, main span length=344m). Long-term data are analyzed and compared with various design codes, guidelines, and other research results. Probability of exceedance are calculated for each criterion. Regarding on deflection limits, Korean Bridge Design Code (Limit State Design) specifies L/400 and L/350 for cable stayed and suspension bridges, respectively. Saadeghvaziri suggested deflection limit based on natural frequency, acceleration limit of 0.5 m/s² and vehicle speed. Various human comfort criteria on vibration are also applied including ISO standards. The results of this study are expected to be useful reference for the design, the proper planning and deflection review of the long span cable bridges around the world. Further researches are required to find the optimum deflection or vibration criteria for long span bridge and their effects on bridge clearance and elevation.</p>

Proposed evaluation methods for vibration serviceability of long span cable bridges

2021 ◽  
Author(s):  
E.-S. Hwang ◽  
M. T. Hwang ◽  
D. Y. Kim ◽  
K. J. Park
Keyword(s):  
Heavy Traffic ◽  
Damping Ratio ◽  
Flexible Structures ◽  
Evaluation Methods ◽  
Monitoring Data ◽  
Long Span ◽  
Vibration Serviceability ◽  
Long Term Monitoring ◽  
Term Monitoring

<p>Vibration serviceability becomes more important considerations in design and maintenance, especially for slender and flexible structures such as long span cable bridges. In this study, various evaluation methods for vibration serviceability for long span cable bridges are proposed. These methods are based on short and long-term monitoring data such as accelerations and displacements of bridges. Proposed methods include (1) method of evaluating vibration amplitude based on Reiher-Meister curves, (2) method of evaluating variations in natural frequencies and damping ratio,</p><p>(3) method of weighted rms(root-mean-square) acceleration based on ISO 2631-1, and (4) probabilistic analysis using long-term monitoring data. These methods are applied to example cable bridge and cases of normal traffic, heavy traffic, windy condition and sudden abnormal vibration are considered. The results of this study are expected to be implemented to real bridge monitoring system for real-time and periodic evaluation of vibration serviceability.</p>

Study on Dynamic Characteristic and Seismic Response of Long-Span Suspension Bridge with 1960 MPa Cable Wire

2016 ◽  
Vol 858 ◽  
pp. 157-162 ◽  
Author(s):  
Hao Lei Wang ◽  
Feng Jie Ma ◽  
Chao Zhu
Keyword(s):  
Dynamic Characteristic ◽  
Seismic Response ◽  
Response Spectrum ◽  
Water Channel ◽  
Suspension Bridge ◽  
Viscous Damper ◽  
Vibration Period ◽  
Long Span ◽  
Design Response Spectrum ◽  
Cable Wire

In order to break through the limitation of the width of river, depth of water, channel and etc., it is an optimal choice to construct a long-span suspension bridge. In a suspension bridge, the main cable is the major bearing member; and the use of super high strength cable wire can lighten the dead weight and obtain an economical design. 1960 Mpa cable wire is adopted by an under-construction suspension bridge, namely Ni-Zhou Channel Bridge, for the first time in China. In this paper, taking the Ni-Zhou Channel Bridge as a case-study, comparative analyses on dynamic characteristic and seismic response of long-span suspension bridge with 1960 Mpa cable wire are performed. Firstly, dynamic calculating model for Ni-Zhou Channel Bridge is built and its dynamic characteristics are studied; then by using response spectrum and time history analysis method, seismic response of Ni-Zhou Channel Bridge is investigated on the basis of design response spectrum and artificial seismic ground motions; finally, the energy dissipation performances of a seismic protection devices (viscous damper) are also discussed. The results show that long-span suspension bridge with 1960 Mpa cable wire has a longer natural vibration period; the use of viscous damper can effectively reduce the peak value of bending moment in stiffening girder. This paper can provide references for the project’s construction.

Building Seismic Vulnerability Study for China High Rises

2013 ◽  
Vol 353-356 ◽  
pp. 2301-2304
Author(s):  
Fan Wu ◽  
Ming Wang ◽  
Xin Yuan Yang
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Earthquake Ground Motion ◽  
Published Data ◽  
Rapid Urbanization ◽  
High Rise ◽  
Story Drift

High-rise buildings, as a result of rapid urbanization in China, become one of popular structure kind. However, there have been few seismic vulnerability studies on high-rise buildings, and few fragility curves have been developed for the buildings. Based on the published data of more than 50 high rises and super high rises, the structural information such as building heights, mode periods, locations and sites, the maximum design story drift ratios, are collected and analyzed. The vulnerability analysis for high rises uses response spectrum displacement as seismic ground motion input, since the structures have comparatively long natural period. Using statistics and regression analysis, the relationship between the maximum story drift ratio and response spectrum displacement is established. Based on height groups and earthquake design codes, the fragility curves of different performance levels can be developed. These curves can provide good loss estimation of high rise structural damage under earthquake ground motion.

Dynamic Property Evaluation of a Long-Span Cable-Stayed Bridge (Sutong Bridge) by a Bayesian Method

2018 ◽  
Vol 19 (01) ◽  
pp. 1940010 ◽  
Author(s):  
Yan-Chun Ni ◽  
Qi-Wei Zhang ◽  
Jian-Feng Liu
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Structural Damage ◽  
Dynamic Properties ◽  
Modal Identification ◽  
Modal Parameters ◽  
Modal Parameter ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Sutong Bridge

Modal identification aims at identifying the dynamic properties including natural frequency, damping ratio, and mode shape, which is an important step in further structural damage detection, finite element model updating, and condition assessment. This paper presents the work on the investigation of the dynamic characteristics of a long-span cable-stayed bridge-Sutong Bridge by a Bayesian modal identification method. Sutong Bridge is the second longest cable-stayed bridge in the world, situated on the Yangtze River in Jiangsu Province, China, with a total length of 2 088[Formula: see text]m. A short-term nondestructive on-site vibration test was conducted to collect the structural response and determine the actual dynamic characteristics of the bridge before it was opened to traffic. Due to the limited number of sensors, multiple setups were designed to complete the whole measurement. Based on the data collected in the field tests, modal parameters were identified by a fast Bayesian FFT method. The first three modes in both vertical and transverse directions were identified and studied. In order to obtain modal parameter variation with temperature and vibration levels, long-term tests have also been performed in different seasons. The variation of natural frequency and damping ratios with temperature and vibration level were investigated. The future distribution of the modal parameters was also predicted using these data.

Investigation on Buckling Behavior of Cylindrical Liquid Storage Tanks Under Seismic Loading: 3rd Report — Proposed Design Procedure Considering Dynamic Response Reduction

2003 ◽  
Author(s):  
Akihisa Sugiyama ◽  
Koji Setta ◽  
Yoji Kawamoto ◽  
Koji Hamada ◽  
Hideyuki Morita ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Seismic Loading ◽  
Absorption Capacity ◽  
Reduction Factor ◽  
Storage Tanks ◽  
Energy Absorption Capacity ◽  
Design Guideline ◽  
Response Reduction Factor ◽  
Liquid Storage ◽  
Thin Walled

As for thin walled cylindrical liquid storage tanks in nuclear power plants, the current elastic design guideline against seismic loading might result in too conservative component design as compared with elasto-plastic design in general industries. Therefore, it is thought possible to make the design guideline more reasonable by taking dynamic response reduction into account. In this series of study, experiments using scaled models were carried out, and seismic behavior of thin walled cylindrical liquid storage tanks was simulated to investigate energy absorption capacity and seismic resistance of those tanks. In this 3rd report of series of studies, seismic behavior of tanks was simulated to estimate a dynamic response reduction factor. This factor is based on the energy absorption capacity of structures. Through experiments and numerical study, a response reduction factor to design thin walled cylindrical liquid storage tanks has been proposed.

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