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CONTENTS
Volume 5, Number 3, September 2013
 

Abstract
Oil, hysteretic and inertial mass dampers are representatives of passive dampers used for smart enhancement of seismic performance of building structures. Since oil dampers have a nonlinear relief mechanism and hysteretic dampers possess nonlinear restoring-force characteristics, several difficulties arise in the evaluation of buildings including such dampers. The purpose of this paper is to propose a practical method for simultaneous optimal use of such dampers. The optimum design problem is formulated so as to minimize the maximum interstory drift under design earthquakes in terms of a set of damper quantities subject to an equality constraint on the total cost of dampers. The proposed method to solve the optimum design problem is a successive procedure which consists of two steps. The first step is a sensitivity analysis by using nonlinear time-history response analyses, and the second step is a modification of the set of damper quantities based upon the sensitivity analysis. Numerical examples are conducted to demonstrate the effectiveness and validity of the proposed design method.

Key Words
optimal damper placement; multiple dampers; variable adaptive step length; nonlinear damper; simultaneous optimization

Address
Department of Architecture and Architectural Engineering, Kyoto University. Kyotodaigaku-Katsura, Nishikyo-ku, Kyoto 615-8540, Japan


Abstract
Margin of safety against potential of progressive collapse is among important features of a structural system. Often eccentricity in plan of a building causes concentration of damage, thus adversely affects its progressive collapse safety margin. In this paper the progressive collapse of symmetric and asymmetric 3-story reinforced concrete ordinary moment resisting frame buildings subjected to the earthquake ground motions are studied. The asymmetric buildings have 5%, 15% and 25% mass eccentricity. The distribution of the damage and spread of the collapse is investigated using nonlinear time history analyses. Results show that potential of the progressive collapse at both stiff and flexible edges of the buildings increases with increase in the level of asymmetry in buildings. It is also demonstrated that \"drift\" as a more easily available global response parameter is a good measure of the potential of progressive collapse rather than much difficult-to-calculate local response parameter of \"number of collapse plastic hinges\"

Key Words
asymmetric buildings; progressive collapse; mass eccentricity; reinforced concrete ordinary moment resisting frame building; nonlinear time history analysis; flexible edge; stiff edge

Address
Int\'l Institute of Earthquake Eng. and Seismology (IIEES), No. 21, Arghavan St., North Dibajee, Farmanieh, Tehran, Iran


Abstract
Two destructive earthquakes occurred on October 23 and November 9, 2011 in Van province of Turkey. The damage in residential units shows significant deviation from the expectation of decreasing damage with increasing distance to epicenter. The most damaged settlement Ercis has the same distance to the epicenter with Muradiye, where no damage occurred while relatively less damage observed in Van having half distance. These three cities seem to have resembling soil conditions. If the damages are evaluated: joint failures and insufficient lap splice lengths are observed to be the main causes of the total collapses in RC buildings. Additionally, low concrete strength, reinforcement detailing mistakes, soft story, heavy overhang, pounding and short columns are among other damage reasons. Examples of damages due to non-structural elements are also given. Remarkable points about seismic damages are: collapsed buildings with shear-walls, heavily damaged buildings despite adequate concrete strength due to detailing mistakes, undamaged two-story adobe buildings close to totally collapsed RC ones and undamaged structural system in buildings with heavily damaged non-structural elements. On the contrary of the common belief that buildings with shear-walls are immune to total collapse among civil engineers, collapse of Gedikbulak primary school is a noteworthy example.

Key Words
Ercis; distance to epicenter; irregularity; reinforced concrete; seismic damage; shear wall; Van

Address
Department of Civil Engineering, Usak University, 64200 Usak, Turkey
Department of Civil Engineering, Pamukkale University, 20070 Denizli, Turkey


Abstract
This paper investigates earthquake response of reinforced concrete regular frames subjected to rebar corrosion. A typical four-story reinforced concrete frame is designed according to Turkish Earthquake Code in order to examine earthquake response. Then different levels of rebar corrosion scenarios are applied to this frame structure. The deteriorated conditions as a result of these scenarios are included loss in cross sectional area of rebar, loss of mechanical properties of rebar, loss in bond strength and variations in damage limits of concrete sections. The frame is evaluated using a nonlinear static analysis in its sound as well as deteriorated conditions. The rebar corrosion effect on the structural response is investigated by comparing the response of the frame in each scenario with respect to the sound condition of the frame. The results shows that the progressive deterioration of the frame over time cause serious reductions on the base shear and top displacement capacity and also structural ductility of the corroded frames. The propagation time, intensity, and extensity of rebar corrosion on the frame are important parameters governing the effect of rebar corrosion on earthquake response of the frame.

Key Words
Earthquake; frame; rebar corrosion; reinforced concrete, response

Address
Department of Civil Engineering, Bursa Technical University, Bursa, Turkey
Department of Construction, Zonguldak Vocational School, Bulent Ecevit University, Zonguldak, Turkey


Abstract
On May 19, 2011 an earthquake struck Simav district of Kütahya which located west of Turkey. According to Disaster and Emergency Management Agency (DEMA), magnitude of this earthquake was ML = 5.7. In this earthquake 2 people lost their lives and considerably damages occurred in the city center and surrounding villages. Damaged structures in the earthquake area did not have adequate earthquake resistance since low quality materials, poor workmanship and improper selection of the structural system. In this study, reasons of damages and failure mechanism of reinforced concrete and masonry buildings were evaluated.

Key Words
Simav earthquake; reinforced concrete buildings; masonry buildings; ground motions

Address
Department of Civil Engineering, Firat University, Elazlg, Turkey
Earthquake Division of the Turkish Disaster and Emergency Management Presidency, Ankara, Turkey


Abstract
The problem of identification of multi-component and (or) spatially varying earthquake support motions based on measured responses in instrumented structures is considered. The governing equations of motion are cast in the state space form and a time domain solution to the input identification problem is developed based on the Kalman and particle filtering methods. The method allows for noise in measured responses, imperfections in mathematical model for the structure, and possible nonlinear behavior of the structure. The unknown support motions are treated as hypothetical additional system states and a prior model for these motions are taken to be given in terms of white noise processes. For linear systems, the solution is developed within the Kalman filtering framework while, for nonlinear systems, the Monte Carlo simulation based particle filtering tools are employed. In the latter case, the question of controlling sampling variance based on the idea of Rao-Blackwellization is also explored. Illustrative examples include identification of multi-component and spatially varying support motions in linear/nonlinear structures.

Key Words
dynamic state estimation; particle filters; force identification; earthquake support motions

Address
Department of Civil Engineering, Indian Institute of Science, Bangalore 560 012, India


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