Drift and Ductility Estimates in Regular Steel MRF Subjected to Ordinary Ground Motions: A Design-Oriented Approach

2008 ◽  
Vol 24 (2) ◽  
pp. 431-451 ◽  
Author(s):  
Theodore L. Karavasilis ◽  
Nikitas Bazeos ◽  
Dimitri E. Beskos
Keyword(s):  
Seismic Design ◽  
Simple Procedure ◽  
Ground Motions ◽  
Plastic Hinge ◽  
Pushover Analysis ◽  
Time History ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Strength Reduction Factor ◽  
Existing Structures

A simple procedure to estimate drift and ductility demands of regular steel frame buildings subjected to ordinary (i.e., without near fault effects) ground motions is described. Given the strength reduction (or behavior) factor, the procedure provides reliable estimates of the maximum roof displacement, the maximum interstorey drift ratio and the maximum rotation ductility along the height of the structure. The strength reduction factor refers to the point of the development of the first plastic hinge in the building and thus, pushover analysis and estimation of the overstrength factor are not required. This important feature enables both the rapid seismic assessment of existing structures and the direct deformation-controlled seismic design of new ones. The derivation of the proposed relations is based on regression analysis of the results of thousands of nonlinear time history analyses of steel frames. A comparison of the proposed method with the procedures adopted in current seismic design codes reveals the efficiency of the former.

Strength reduction factor of self-centering structures under near-fault pulse-like ground motions

2020 ◽  
Vol 24 (1) ◽  
pp. 119-133
Author(s):  
Huihui Dong ◽  
Qiang Han ◽  
Xiuli Du ◽  
Canxing Qiu
Keyword(s):  
Ground Motions ◽  
Time History ◽  
Reduction Factor ◽  
Strength Reduction ◽  
The Self ◽  
Hysteretic Behavior ◽  
Hysteretic Model ◽  
Strength Reduction Factor ◽  
Vibration Period ◽  
Near Fault

Many studies on the strength reduction factor mainly focused on structures with the conventional hysteretic models. However, for the self-centering structure with the typical flag-shaped hysteretic behavior, the corresponding study is limited. The main purpose of this study is to investigate the strength reduction factor of the self-centering structure with flag-shaped hysteretic behavior subjected to near-fault pulse-like ground motions by the time history analysis. For this purpose, the smooth flag-shaped model based on Bouc-Wen model which can show flag-shaped hysteretic behavior is first described. The strength reduction factor spectra of the flag-shaped model are then calculated under 85 near-fault pulse-like ground motions. The influences of the ductility level, vibration period, site condition, hysteretic parameter, and hysteretic model are investigated statistically. For comparison, the strength reduction factors under ordinary ground motions are also analyzed. The results show that the strength reduction factor from near-fault pulse-like ground motions is smaller. Finally, a predictive model is proposed to estimate the strength reduction factor for the self-centering structure with the flag-shaped model under near-fault pulse-like ground motions.

Studies on Seismic Demand Spectra Based on Strength Reduction Factor

2011 ◽  
Vol 243-249 ◽  
pp. 4047-4051
Author(s):  
Xiao Li Zhu ◽  
Gao Hang Cui ◽  
Xia Xin Tao
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Structural Characteristics ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Seismic Demand ◽  
Capacity Design ◽  
Strength Reduction Factor ◽  
Seismic Design Code ◽  
Bridge Structures

For resolving the practical problem about bridge structures, according to the seismic damage regularity and the structural characteristics, the capacity design method of bridge structure was introduced. In order to account synthetically for the influence factors and convert the inelastic seismic design method into the pseudo-static method, which is easily accepted by engineers, the strength reduction factor was commonly used in seismic design of structures. Based on the principles of the inelastic spectrum established by using the relationship between the strength reduction factor R and ductility factor μ, the seismic demand spectra were obtained from the design spectrum of the Highway Engineering Seismic Design Code (JTJ 004-89). This will be beneficial to the earthquake-resistant capacity design in practical bridge structures.

scholarly journals An Improved Multidimensional MPA Procedure for Bidirectional Earthquake Excitations

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Feng Wang ◽  
Jian-Gang Sun ◽  
Ning Zhang
Keyword(s):  
Pushover Analysis ◽  
Structural Response ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Multidimensional Analysis ◽  
Strength Reduction Factor ◽  
Earthquake Excitation ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
Modal Pushover

Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA) method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two components earthquake excitations, and independent analysis in each direction is not required and the application of simplified superposition formulas is avoided. The strength reduction factor spectra based on superposition of earthquake excitations are discussed and compared with the traditional strength reduction factor spectra. The step-by-step procedure is proposed to estimate seismic demands of structures. Two examples are implemented to verify the accuracy of the method, and the results of the examples show that (1) the IMMPA method can be used to estimate the responses of structure subjected to bidirectional earthquake excitations. (2) Along with increase of peak of earthquake acceleration, structural response deviation estimated with the IMMPA method may also increase. (3) Along with increase of the number of total floors of structures, structural response deviation estimated with the IMMPA method may also increase.

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