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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Earthquakes and Structures
Journal Basic Information
Journal DOI :
Editor in Chief :
Izuru Takewaki / Stavros A. / Anagnostopoulos / Jerome P. Lynch
Volume & Issues
Volume 7, Issue 6 - Dec 2014
Volume 7, Issue 5 - Nov 2014
Volume 7, Issue 4 - Oct 2014
Volume 7, Issue 3 - Sep 2014
Volume 7, Issue 2 - Aug 2014
Volume 7, Issue 1 - Jul 2014
Volume 6, Issue 6 - Jun 2014
Volume 6, Issue 5 - May 2014
Volume 6, Issue 4 - Apr 2014
Volume 6, Issue 3 - Mar 2014
Volume 6, Issue 2 - Feb 2014
Volume 6, Issue 1 - Jan 2014
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Experimental and numerical studies on seismic performance of hollow RC bridge columns
Han, Qiang ; Zhou, Yulong ; Du, Xiuli ; Huang, Chao ; Lee, George C. ;
Earthquakes and Structures, volume 7, issue 3, 2014, Pages 251~269
DOI : 10.12989/eas.2014.7.3.251
To investigate the seismic performance and to obtain quantitative parameters for the requirement of performance-based bridge seismic design approach, 12 reinforced concrete (RC) hollow rectangular bridge column specimens were tested under constant axial load and cyclic bending. Parametric study is carried out on axial load ratio, aspect ratio, longitudinal reinforcement ratio and transverse reinforcement ratio. The damage states of these column specimens were related to engineering limit states to determine the quantitative criteria of performance-based bridge seismic design. The hysteretic behavior of bridge column specimens was simulated based on the fiber model in OpenSees program and the results of the force-displacement hysteretic curves were well agreed with the experimental results. The damage states of residual cracking, cover spalling, and core crushing could be well related to engineering limit states, such as longitudinal tensile strains of reinforcement or compressive strains of concrete, etc. using cumulative probability curves. The ductility coefficient varying from 3.71 to 8.29, and the equivalent viscous damping ratio varying from 0.19 to 0.31 could meet the requirements of seismic design.
Life-cycle cost optimization of steel moment-frame structures: performance-based seismic design approach
Kaveh, A. ; Kalateh-Ahani, M. ; Fahimi-Farzam, M. ;
Earthquakes and Structures, volume 7, issue 3, 2014, Pages 271~294
DOI : 10.12989/eas.2014.7.3.271
In recent years, along with the advances made in performance-based design optimization, the need for fast calculation of response parameters in dynamic analysis procedures has become an important issue. The main problem in this field is the extremely high computational demand of time-history analyses which may convert the solution algorithm to illogical ones. Two simplifying strategies have shown to be very effective in tackling this problem; first, simplified nonlinear modeling investigating minimum level of structural modeling sophistication, second, wavelet analysis of earthquake records decreasing the number of acceleration points involved in time-history loading. In this paper, we try to develop an efficient framework, using both strategies, to solve the performance-based multi-objective optimal design problem considering the initial cost and the seismic damage cost of steel moment-frame structures. The non-dominated sorting genetic algorithm (NSGA-II) is employed as the optimization algorithm to search the Pareto optimal solutions. The constraints of the optimization problem are considered in accordance with Federal Emergency Management Agency (FEMA) recommended design specifications. The results from numerical application of the proposed framework demonstrate the capabilities of the framework in solving the present multi-objective optimization problem.
Seismic fragility analysis of conventional and viscoelastically damped moment resisting frames
Guneyisi, Esra Mete ; Sahin, Nazli Deniz ;
Earthquakes and Structures, volume 7, issue 3, 2014, Pages 295~315
DOI : 10.12989/eas.2014.7.3.295
This paper presents the results of an analytical study on seismic reliability of viscoelastically damped frame systems in comparison with that of conventional moment resisting frame systems. In order to exhibit the reliability of the frame systems with viscoelastic dampers, seismic reliability analyses were carried out for steel framed buildings, 5 and 12 storeys in height, designed as: (a) Case 1: Conventional moment resisting frame, (b) Case 2: Frame with viscoelastic dampers providing supplemental effective damping ratio of 10%, and (c) Case 3: Frame with viscoelastic dampers providing supplemental effective damping ratio of 20%. Nonlinear time history analyses were utilized to develop seismic fragility curves whilst monitoring various performance objectives. To obtain robust estimators of the seismic reliability, a database including 15 natural earthquake ground motion records with markedly different characteristics was employed in the fragility analysis. The results indicate that depending upon the supplemental effective damping ratio, frames designed with viscoelastic dampers have considerably lower annual probability of exceedance of performance limit states for structural components, showing up to a five-fold reduction in comparison to conventionally designed moment resisting frame system.
Cyclic test for solid steel reinforced concrete frames with special-shaped columns
Liu, Zu Q. ; Xue, Jian Y. ; Zhao, Hong T. ; Gao, Liang ;
Earthquakes and Structures, volume 7, issue 3, 2014, Pages 317~331
DOI : 10.12989/eas.2014.7.3.317
An experimental study was performed to investigate the seismic performance of solid steel reinforced concrete (SRC) frames with special-shaped columns that are composed of SRC special-shaped columns and reinforced concrete beams. For this purpose, two models of two-bay and three-story frame, including an edge frame and a middle frame, were designed and tested. The failure process and patterns were observed. The mechanical behaviors such as load-displacement hysteretic loops and skeleton curves, load bearing capacity, drift ratio, ductility, energy dissipation and stiffness degradation of test specimens were analyzed. Test results show that the failure mechanism of solid SRC frame with special-shaped columns is the beam-hinged mechanism, satisfying the seismic design principle of "strong column and weak beam". The hysteretic loops are plump, the ductility is good and the capacity of energy dissipation is strong, indicating that the solid SRC frame with special-shaped columns has excellent seismic performance, which is better than that of the lattice SRC frame with special-shaped columns. The ultimate elastic-plastic drift ratio is larger than the limit value specified by seismic code, showing the high capacity of collapse resistance. Compared with the edge frame, the middle frame has higher carrying capacity and stronger energy dissipation, but the ductility and speed of stiffness degradation are similar. All these can be helpful to the designation of solid SRC frame with special-shaped columns.
Investigation of elasto-plastic seismic response analysis method for complex steel bridges
Tang, Zhanzhan ; Xie, Xu ; Wang, Yan ; Wang, Junzhe ;
Earthquakes and Structures, volume 7, issue 3, 2014, Pages 333~347
DOI : 10.12989/eas.2014.7.3.333
Multi-scale model can take both computational efficiency and accuracy into consideration when it is used to conduct elasto-plastic seismic response analysis for complex steel bridges. This paper proposed a method based on pushover analysis of member sharing the same section pattern to verify the accuracy of multi-scale model. A deck-through type steel arch bridge with a span length of 200m was employed for seismic response analysis using multi-scale model and fiber model respectively, the validity and necessity of elasto-plastic seismic analysis for steel bridge by multi-scale model was then verified. The results show that the convergence of load-displacement curves obtained from pushover analysis for members having the same section pattern can be used as a proof of the accuracy of multi-scale model. It is noted that the computational precision of multi-scale model can be guaranteed when length of shell element segment is 1.40 times longer than the width of section where was in compression status. Fiber model can only be used for the predictions of the global deformations and the approximate positions of plastic areas on steel structures. However, it cannot give exact prediction on the distribution of plastic areas and the degree of the plasticity.
Blast load induced response and the associated damage of buildings considering SSI
Mahmoud, Sayed ;
Earthquakes and Structures, volume 7, issue 3, 2014, Pages 349~365
DOI : 10.12989/eas.2014.7.3.349
The dynamic response of structures under extremely short duration dynamic loads is of great concern nowadays. This paper investigates structures' response as well as the associated structural damage to explosive loads considering and ignoring the supporting soil flexibility effect. In the analysis, buildings are modeled by two alternate approaches namely, (1) building with fixed supports, (2) building with supports accounting for soil-flexibility. A lumped parameter model with spring-dashpot elements is incorporated at the base of the building model to simulate the horizontal and rotational movements of supporting soil. The soil flexibility for various shear wave velocities has been considered in the investigation. In addition, the influence of variation of lateral natural periods of building models on the obtained response and peak response time-histories besides damage indices has also been investigated under blast loads with different peak over static pressures. The Dynamic response is obtained by solving the governing equations of motion of the considered building model using a developed Matlab code based on the finite element toolbox CALFEM. The predicted results expressed in time-domain by the building model incorporating SSI effect are compared with the corresponding model results ignoring soil flexibility effect. The results show that the effect of surrounding soil medium leads to significant changes in the obtained dynamic response of the considered systems and hence cannot be simply ignored in damage assessment and response time-histories of structures where it increases response and amplifies damage of structures subjected to blast loads. Moreover, the numerical results provide an understanding of level of damage of structure through the computed damage indices.
Correlation between parameters of pulse-type motions and damage of low-rise RC frames
Cao, Vui Van ; Ronagh, Hamid Reza ;
Earthquakes and Structures, volume 7, issue 3, 2014, Pages 365~384
DOI : 10.12989/eas.2014.7.3.365
The intensity of a ground motion can be measured by a number of parameters, some of which might exhibit robust correlations with the damage of structures subjected to that motion. In this study, 204 near-fault pulse-type records are selected and their seismic parameters are determined. Time history and damage analyses of a tested 3-storey reinforced concrete frame representing for low-rise reinforced concrete buildings subjected to those earthquake motions are performed after calibration and comparison with the available experimental results. The aim of this paper is to determine amongst several available seismic parameters, the ones that have strong correlations with the structural damage measured by a damage index and the maximum inter-story drift. The results show that Velocity Spectrum Intensity is the leading parameter demonstrating the best correlation, followed by Housner Intensity, Spectral Acceleration and Spectral Displacement. These seismic parameters are recommended as reliable parameters of near-fault pulse-type motions related to damage potential of low-rise reinforced concrete structures. The results also reaffirm that the conventional and widely used parameter of Peak Ground Acceleration does not exhibit a good correlation with the structural damage.
Influence of mass and contact surface on pounding response of RC structures
Khatiwada, Sushil ; Larkin, Tam ; Chouw, Nawawi ;
Earthquakes and Structures, volume 7, issue 3, 2014, Pages 385~400
DOI : 10.12989/eas.2014.7.3.385
Pounding damage to bridges and buildings is observed in most major earthquakes. The damage mainly occurs in reinforced concrete slabs, e.g. building floors and bridge decks. This study presents the results from pounding of reinforced concrete slabs. A parametric investigation was conducted involving the mass of the pendulums, the relative velocities of impact and the geometry of the contact surface. The effect of these parameters on the coefficient of restitution and peak impact acceleration is shown. In contrast to predictions from numerical force models, it was observed that peak acceleration is independent of mass. The coefficient of restitution is affected by the impact velocity, total participating mass and the mass ratio of striker and struck block.