scholarly journals Effect of Damping and Yielding on the Seismic Response of 3D Steel Buildings with PMRF

2014 ◽  
Vol 2014 ◽  
pp. 1-21 ◽  
Author(s):  
Alfredo Reyes-Salazar ◽  
Achintya Haldar ◽  
Ramon Eduardo Rodelo-López ◽  
Eden Bojórquez
Keyword(s):  
Seismic Response ◽  
Three Dimensional ◽  
Lateral Force ◽  
Viscous Damping ◽  
Steel Buildings ◽  
Local Response ◽  
Equivalent Viscous Damping ◽  
Response Parameter ◽  
Mdof Systems ◽  
Crude Approximation

The effect of viscous damping and yielding, on the reduction of the seismic responses of steel buildings modeled as three-dimensional (3D) complex multidegree of freedom (MDOF) systems, is studied. The reduction produced by damping may be larger or smaller than that of yielding. This reduction can significantly vary from one structural idealization to another and is smaller for global than for local response parameters, which in turn depends on the particular local response parameter. The uncertainty in the estimation is significantly larger for local response parameter and decreases as damping increases. The results show the limitations of the commonly used static equivalent lateral force procedure where local and global response parameters are reduced in the same proportion. It is concluded that estimating the effect of damping and yielding on the seismic response of steel buildings by using simplified models may be a very crude approximation. Moreover, the effect of yielding should be explicitly calculated by using complex 3D MDOF models instead of estimating it in terms of equivalent viscous damping. The findings of this paper are for the particular models used in the study. Much more research is needed to reach more general conclusions.

Combination rules and critical seismic response of steel buildings modeled as complex MDOF systems

2016 ◽  
Vol 10 (1) ◽  
pp. 211-238 ◽  
Author(s):  
Alfredo Reyes-Salazar ◽  
Federico Valenzuela-Beltran ◽  
David de Leon-Escobedo ◽  
Eden Bojorquez-Mora ◽  
Arturo Lopez Barraza
Keyword(s):  
Seismic Response ◽  
Steel Buildings ◽  
Combination Rules ◽  
Mdof Systems

Ductility Reduction Factors for Steel Buildings Modeled as 2D and 3D Structures

2014 ◽  
Vol 595 ◽  
pp. 166-172
Author(s):  
Alfredo Reyes-Salazar ◽  
Eden Bojorquez ◽  
Achintya Haldar ◽  
Arturo Lopez-Barraza ◽  
J. Luz Rivera-Salas
Keyword(s):  
Lateral Force ◽  
Reduction Factor ◽  
Steel Buildings ◽  
Structural Representation ◽  
Global Response ◽  
A Value ◽  
Mdof Systems ◽  
Moment Resisting ◽  
2D And 3D ◽  
Reduction Factors

The global ductility parameter (μG), commonly used to represent the capacity of a structure to dissipate energy, and the associated ductility reduction factor (Rμ), are estimated for steel buildings with perimeter moment resisting frames (PMRF), which are modeled as 2D and 3D complex MDOF systems. Results indicate that the μG value of 4, commonly assumed for moment resisting steel frames, cannot be justified. A value of 3 is more reasonable. The values of μG and Rμ may be quite different for 2D and 3D structural representations or for local and global response parameters, showing the limitation of the commonly used Equivalent Lateral Force Procedure (ELFP). Thus, the ductility and ductility reduction factors obtained from simplified structural representation must be taken with caution.

ENERGY-BASED APPROACH TO ESTIMATE SEISMIC DEMANDS FOR ASYMMETRIC BUILDINGS

2010 ◽  
Vol 04 (03) ◽  
pp. 215-230 ◽  
Author(s):  
RAMIN TABATABAEI ◽  
HAMED SAFFARI
Keyword(s):  
Seismic Response ◽  
Dynamic Properties ◽  
Pushover Analysis ◽  
Three Dimensional ◽  
Lateral Force ◽  
Three Dimensional Model ◽  
Seismic Demands ◽  
Asymmetric Buildings ◽  
Plastic Mechanism ◽  
Response History Analysis

In this paper, an energy-based approach to estimate the inelastic response of buildings is presented. In order to estimate torsional effects on the seismic response of structure, the associated plastic mechanism is developed in the three-dimensional model using an adapted version of the DRAIN-3DX program. The changing dynamic properties due to plastic mechanism are used for the calculation of modal lateral loads. Thus, the effects of both stiffness changes and localized response mechanisms at the structure under modal loading are included. The total input energy due to seismic loading is composed of both work done by (1) lateral force pattern acting through the translation displacement and (2) torsion acting through the rotation of each floor. For assessment of the seismic response of asymmetric buildings, the proposed procedure is shown to provide superior results compared to those obtained through deployment of the other methods commonly used: the adaptive modal combination (AMC) procedure, the modal pushover analysis (MPA), and the response history analysis (RHA) approach.

Design and structural performance measurements of a novel multi-cantilever foil bearing

2014 ◽  
Vol 229 (10) ◽  
pp. 1830-1838 ◽  
Author(s):  
Kai Feng ◽  
Xueyuan Zhao ◽  
Zhiyang Guo
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Load ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Viscous Damping ◽  
Equivalent Viscous Damping ◽  
Foil Bearing ◽  
Load Tests ◽  
Stiffness And Damping ◽  
Motion Amplitude

With increasing need for high-speed, high-temperature, and oil-free turbomachinery, gas foil bearings (GFBs) have been considered to be the best substitutes for traditional oil-lubricated bearings. A multi-cantilever foil bearing (MCFB), a novel GFB with multi-cantilever foil strips serving as the compliant underlying structure, was designed, fabricated, and tested. A series of static and dynamic load tests were conducted to measure the structural stiffness and equivalent viscous damping of the prototype MCFB. Experiments of static load versus deflection showed that the proposed bearing has a large mechanical energy dissipation capability and a pronounced nonlinear static stiffness that can prevents overly large motion amplitude of journal. Dynamic load tests evaluated the influence of motion amplitude, loading orientation and misalignment on the dynamic stiffness and equivalent viscous damping with respect to excitation frequency. The test results demonstrated that the dynamic stiffness and damping are strongly dependent on the excitation frequency. Three motion amplitudes were applied to the bearing housing to investigate the effects of motion amplitude on the dynamic characteristics. It is noted that the bearing dynamic stiffness and damping decreases with incrementally increasing motion amplitudes. A high level of misalignment can lead to larger static and dynamic bearing stiffness as well as to larger equivalent viscous damping. With dynamic loads applied to two orientations in the bearing midplane separately, the dynamic stiffness increases rapidly and the equivalent viscous damping declines slightly. These results indicate that the loading orientation is a non-negligible factor on the dynamic characteristics of MCFBs.

Effect of Pile-Soil-Structure Interaction on the Cable-Stayed Bridge in Response to the Earthquake

2014 ◽  
Vol 539 ◽  
pp. 731-735 ◽  
Author(s):  
Yu Chen
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Soil Structure ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Cable Stayed Bridge ◽  
Three Dimensional Finite Element

In this thesis, based on the design of a 140+90m span unusual single tower and single cable plane cable-stayed bridge, free vibration characteristics and seismic response are investigated; three dimensional finite element models of a single tower cable-stayed bridge with and without the pile-soil-structure interaction are established respectively by utilizing finite element software MIDAS/CIVIL, seismic response of Response spectrum and Earthquake schedule are analyzed respectively and compared. By the comparison of the data analysis, for small stiffness span cable-stayed bridge, the pile-soil-structure interaction can not be ignored with calculation and analysis of seismic response.

Numerical exploration on snap buckling of a pre-stressed hemispherical gridshell

2021 ◽  
pp. 1-11
Author(s):  
Weicheng Huang ◽  
Longhui Qin ◽  
Qiang Chen
Keyword(s):  
Three Dimensional ◽  
Energy Functional ◽  
Elastic Rods ◽  
Geometrically Nonlinear ◽  
Local Response ◽  
Micro Electro Mechanical Systems ◽  
One Dimensional ◽  
Numerical Exploration ◽  
Planar Grid ◽  
Fundamental Understanding

Abstract Motivated by the observations of snap-through phenomena in pre-stressed strips and curved shells, we numerically investigate the snapping of a pre-buckled hemispherical gridshell under apex load indentation. Our experimentally validated numerical framework on elastic gridshell simulation combines two components: (i) Discrete Elastic Rods method, for the geometrically nonlinear description of one dimensional rods; and (ii) a naive penalty-based energy functional, to perform the non-deviation condition between two rods at joint. An initially planar grid of slender rods can be actuated into a three dimensional hemispherical shape by loading its extremities through a prescribed path, known as buckling induced assembly; next, this pre-buckled structure can suddenly change its bending direction at some threshold points when compressing its apex to the other side. We find that the hemispherical gridshell can undergo snap-through buckling through two different paths based on two different apex loading conditions. The first critical snap-through point slightly increases as the number of rods in gridshell structure becomes denser, which emphasizes the mechanically nonlocal property in hollow grids, in contrast to the local response of continuum shells. The findings may bridge the gap among rods, grids, knits, and shells, for a fundamental understanding of a group of thin elastic structures, and inspire the design of novel micro-electro-mechanical systems and functional metamaterials.

scholarly journals Viscoelastic Boundary Conditions for Multiple Excitation Sources in the Time Domain

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Chen Xia ◽  
Chengzhi Qi ◽  
Xiaozhao Li
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Time Domain ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Seismic Loads ◽  
Element Analysis ◽  
Artificial Boundaries ◽  
The Time Domain ◽  
Transmitting Boundaries

Transmitting boundaries are important for modeling the wave propagation in the finite element analysis of dynamic foundation problems. In this study, viscoelastic boundaries for multiple seismic waves or excitations sources were derived for two-dimensional and three-dimensional conditions in the time domain, which were proved to be solid by finite element models. Then, the method for equivalent forces’ input of seismic waves was also described when the proposed artificial boundaries were applied. Comparisons between numerical calculations and analytical results validate this seismic excitation input method. The seismic response of subway station under different seismic loads input methods indicates that asymmetric input seismic loads would cause different deformations from the symmetric input seismic loads, and whether it would increase or decrease the seismic response depends on the parameters of the specific structure and surrounding soil.

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