The performance-based seismic response of special steel MRF: Effects of pulse-like ground motion and foundation safety factor

Structures ◽  
2020 ◽  
Vol 28 ◽  
pp. 127-140
Author(s):  
Sima Mashhadi ◽  
Azita Asadi ◽  
Farshad Homaei ◽  
Hamed Tajammolian
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Safety Factor ◽  
Special Steel ◽  
Steel Mrf

scholarly journals Seismic rocking effects on a mine tower under induced and natural earthquakes

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Piotr Adam Bońkowski ◽  
Juliusz Kuś ◽  
Zbigniew Zembaty
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Ground Surface ◽  
Tall Buildings ◽  
Earthquake Ground Motion ◽  
Seismic Action ◽  
Seismic Effects ◽  
Copper Ore ◽  
Rotational Components ◽  
Natural Earthquakes

AbstractRecent research in engineering seismology demonstrated that in addition to three translational seismic excitations along x, y and z axes, one should also consider rotational components about these axes when calculating design seismic loads for structures. The objective of this paper is to present the results of a seismic response numerical analysis of a mine tower (also called in the literature a headframe or a pit frame). These structures are used in deep mining on the ground surface to hoist output (e.g. copper ore or coal). The mine towers belong to the tall, slender structures, for which rocking excitations may be important. In the numerical example, a typical steel headframe 64 m high is analysed under two records of simultaneous rocking and horizontal seismic action of an induced mine shock and a natural earthquake. As a result, a complicated interaction of rocking seismic effects with horizontal excitations is observed. The contribution of the rocking component may sometimes reduce the overall seismic response, but in most cases, it substantially increases the seismic response of the analysed headframe. It is concluded that in the analysed case of the 64 m mining tower, the seismic response, including the rocking ground motion effects, may increase up to 31% (for natural earthquake ground motion) or even up to 135% (for mining-induced, rockburst seismic effects). This means that not only in the case of the design of very tall buildings or industrial chimneys but also for specific yet very common structures like mine towers, including the rotational seismic effects may play an important role.

Wave Passage and Ground Motion Incoherency Effects on Seismic Response of an Extended Bridge

2011 ◽  
Vol 16 (3) ◽  
pp. 364-374 ◽  
Author(s):  
Aman M. Mwafy ◽  
Oh-Sung Kwon ◽  
Amr Elnashai ◽  
Youssef M. A. Hashash
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Wave Passage

Seismic response and retrofit of industrial brick masonry chimneys

1992 ◽  
Vol 19 (1) ◽  
pp. 117-128 ◽  
Author(s):  
A. Ghobarah ◽  
T. Baumber
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Strong Motion ◽  
Brick Masonry ◽  
Wind Loading ◽  
Earthquake Ground Motion ◽  
Lumped Mass ◽  
Mass System ◽  
Higher Modes ◽  
Recent Earthquakes

During recent earthquakes, the documented cases of collapsed unreinforced brick masonry industrial chimneys are numerous. Observed modes of structural failure are either total collapse or sometimes collapse or damage of the top third of the structure. The objective of this study is to analyze and explain the modes of observed failure of masonry chimneys during earthquake events, and to evaluate two retrofit systems for existing chimneys in areas of high seismicity. The behaviour of the masonry chimney, when subjected to earthquake ground motion, was modelled using a lumped mass system. Several actual strong motion records were used as input to the model. The shear, moment, and displacement responses to the earthquake ground motion were evaluated for various chimney configurations. It was found that the failure of the chimney at its base is the result of the fundamental mode of vibration. Failure at the top third of the structure due to the higher modes of vibration is possible when the chimney is subjected to high frequency content earthquakes. Higher modes, which are normally not of concern under wind loading, were shown to be critical in seismic design. Post-tensioning and the reinforcing steel cage were found to be effective retrofit systems. Key words: masonry, chimneys, behaviour, analysis, design, retrofit, dynamic, earthquakes, seismic response.

scholarly journals Multi-angle and nonuniform ground motions on cable-stayed bridges

2021 ◽  
pp. 875529302110513
Author(s):  
Eleftheria Efthymiou ◽  
Alfredo Camara
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Seismic Waves ◽  
Incidence Angle ◽  
Design Parameters ◽  
System Configuration ◽  
Cable System ◽  
Parametric Problem ◽  
Wide Range ◽  
Cable Stayed Bridges

The definition of the spatial variability of the ground motion (SVGM) is a complex and multi-parametric problem. Its effect on the seismic response of cable-stayed bridges is important, yet not entirely understood to date. This work examines the effect of the SVGM on the seismic response of cable-stayed bridges by means of the time delay of the ground motion at different supports, the loss of coherency of the seismic waves, and the incidence angle of the seismic waves. The focus herein is the effect of the SVGM on cable-stayed bridges with various configurations in terms of their length and of design parameters such as the pylon shape and the pylon–cable system configuration. The aim of this article is to provide general conclusions that are applicable to a wide range of canonical cable-stayed bridges and to contribute to the ongoing effort to interpret and predict the effect of the SVGM in long structures. This work shows that the effect of the SVGM on the seismic response of cable-stayed bridges varies depending on the pylon shape, height, and section dimensions; on the cable-system configuration; and on the response quantity of interest. Furthermore, the earthquake incidence angle defines whether the SVGM is important to the seismic response of the cable-stayed bridges. It is also confirmed that the SVGM excites vibration modes of the bridges that do not contribute to their seismic response when identical support motion is considered.

Nonstationary Probabilistic Seismic Response Analysis of Nonlinear Soil Profile under Bidirectional Dynamic Loading

2012 ◽  
Vol 193-194 ◽  
pp. 949-953
Author(s):  
Xiao Dong Pan ◽  
Jia En Zhong ◽  
Chao Chao He
Keyword(s):  
Spectral Density ◽  
Seismic Response ◽  
Ground Motion ◽  
Power Spectral Density ◽  
Soil Profile ◽  
Response Analysis ◽  
Time Varying ◽  
Seismic Response Analysis ◽  
Dynamic Reliability ◽  
Power Spectral

In this paper, according to the characteristics of near-fault earthquakes, combined with the strong ground motion attenuation law in China, the nonstationary power spectrum of bidirectional ground motion input is obtained through random vibration analysis. By introducing the pseudo excitation algorithm, the evolutionary power spectral density (PSD) of acceleration at the engineering bedrock is handled as the nonstationary pseudo input, and the Hardin-Drnevich hyperbolic model is utilized to take into account the nonlinearity of soil layer. On this basis, finite element method in the time domain and frequency domain are used for seismic response analysis of soil profile. Values including various time-varying power spectral density of the dynamic response, time varying RMS and time-dependent reliability at different threshold can be obtained by calculating, which provides a basis for the analysis of the foundation dynamic reliability assessment.

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