Seismic Response of Single-Degree-of-Freedom Systems Representing Low-Ductility Steel Concentrically Braced Frames with Reserve Capacity

2013 ◽  
Vol 139 (2) ◽  
pp. 199-211 ◽  
Author(s):  
Gang Li ◽  
Larry A. Fahnestock
Keyword(s):  
Seismic Response ◽  
Degree Of Freedom ◽  
Reserve Capacity ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Concentrically Braced

Seismic Response Reduction Caused by Coupling Between Beam-Type and Oval-Type Vibrations of a Cylindrical Water Storage Tank Under Large Excitation

2007 ◽  
Author(s):  
Akira Maekawa ◽  
Katsuhisa Fujita ◽  
Michiaki Suzuki
Keyword(s):  
Seismic Response ◽  
Water Storage ◽  
Degree Of Freedom ◽  
Seismic Excitation ◽  
System Model ◽  
Single Degree Of Freedom ◽  
Water Storage Tank ◽  
Single Degree ◽  
Input Acceleration ◽  
Beam Type

This study describes the response reduction caused by coupling between the beam-type and the oval-type vibrations of a cylindrical water storage tank under seismic excitation. In this study, the seismic response experiment is performed by using a 1/10 reduced scale model of an actual tank and then numerical simulation is performed by the simplified model. The authors conducted the sinusoidal response experiment for the tank and reported that the coupling between the beam-type and the oval-type vibrations causes the resonance frequency of the beam-type vibration to shift to the lower frequency and the response in the beam-type vibration (the response of the tank) to reduce. The seismic response experiment of the tank model filled with water up to 95% is performed by a shaking table. The El Centro 1940 NS and the improved standard seismic wave for Japanese LWR are used as the input seismic wave. The experimental results show that the maximum response acceleration does not enlarge linearly as the maximum input acceleration increases. The dominant resonance frequency slightly shifts to the lower frequency as the maximum input acceleration increases. It is concluded that the coupling between the beam-type and the oval-type vibrations make an influence on the beam-type vibration in seismic excitation. In the meantime, the authors propose the nonlinear single-degree-of-freedom system model to explain that the vibration response of the tank reduces. This model is based on geometric nonlinearity due to the out-of-plane deformation of the side-wall of the tank caused by the oval-type vibration. The numerical simulation of the seismic response is conducted using the nonlinear single-degree-of-freedom system model proposed by the authors. The analytical results agree with the experimental results as a general trend. Therefore, it is concluded that the response reduction of the tank is generated by coupling between the beam-type and the oval-type vibrations in the seismic excitation as well as the sinusoidal excitation. In addition, the response reduction rate of the tank under much larger seismic excitation can be estimated by using the nonlinear single-degree-of-freedom system model.

scholarly journals The Effect of Local Fuse on Behavior of Concentrically Braced Frame by a Numerical Study

2018 ◽  
Vol 4 (3) ◽  
pp. 655 ◽  
Author(s):  
Ali Kachooee ◽  
Mohammad Ali Kafi ◽  
Mohsen Gerami
Keyword(s):  
Seismic Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Compressive Loading ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Reduced Cross Section ◽  
Braced Frame ◽  
Concentrically Braced Frame ◽  
Concentrically Braced

The concentrically braced frames (CBFs) are one of the most widely used lateral load-resisting systems. Seismic performance of these structures has a weakness that is due to the brace buckling at a lower loading than the ultimate compressive loading capacity. In this paper, attempt is made to enhance the seismic response of CBFs through utilizing a local fuse. For this purpose, first the formulation of fuse area and length are presented. Then based on this formulation, several numerical models have been built and analyzed to examine the effect of implementing this fuse on seismic response of CBFs. From the analyses results, it is found that if the reduced cross-section fuse (RCF) is properly designed and also the end of brace is fixed, the CBFs with equal energy dissipation capacity, that are equipped with this fuse exhibit a better ductility than the customary CBFs.

Parameters Study of Steel Concentrically-Braced Frames Using IDA

2013 ◽  
Vol 351-352 ◽  
pp. 223-226
Author(s):  
Zhi Qian Dong ◽  
Gang Li ◽  
Hong Nan Li
Keyword(s):  
Dynamic Instability ◽  
Lateral Force ◽  
Incremental Dynamic Analysis ◽  
Reserve Capacity ◽  
Analysis Method ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Study Variable ◽  
Concentrically Braced ◽  
Moderate Seismic Regions

Steel concentrically-braced frames (CBFs) as a lateral force resisting system are widely used in moderate seismic regions. The collapse capacity of CBF is uncertain in prior study so that an appropriate analysis method is hard to hunt. Incremental Dynamic Analysis (IDA) is an efficient method to evaluate the dynamic instability of structure. The IDA is incorporated in evaluation of collapse capacity of CBFs systems and IDA-based collapse ductility spectra of CBFs are concluded in this study. Variable periods range of CBFs systems considering reserve capacity are determined based on the IDA.

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