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CONTENTS
Volume 6, Number 5, May 2014
 

Abstract
The paper presents the field investigations and seismic analyses of a historical masonry brick minaret damaged during October 23 (Erciş) and November 9 (Edremit), 2011 Van earthquakes in Turkey. Ulu Mosque Minaret located on Tebriz Kapi Street in the city centre of Van, Turkey is selected for investigation. Two earthquakes hit the minaret within seventeen days, causing progressive damage. It was seen from the field investigations that the minaret was heavily damaged. To validate the field investigations, three dimensional finite element model of the minaret is constituted by ANSYS software using relievo drawings. Finite element model of the minaret is analyzed under the Van earthquake records to determine the seismic behavior. The displacements, maximum and minimum principal stresses and strains are obtained from the analyses and compared with field observations.

Key Words
earthquake damages; seismic analyses; masonry minarets; Ulu Mosque minaret; Van earthquakes in 2011; field investigations

Address
Murat Muvafik: Department of Civil Engineering, Yuzuncu Yil Universitesi, 65080, Van, Turkey

Abstract
Progressive collapse, which is referred to as the collapse of the entire building under local damages, is a common failure mode happened by earthquakes. The collapse process highly depends on the whole structural system. Since, asymmetry of the building plan leads to the local damage concentration; it may intensify the progressive collapse mechanism of asymmetric buildings. In this research the progressive collapse of regular and irregular 6-story RC ordinary moment resisting frame buildings are studied in the presence of the earthquake loads. Collapse process and collapse propagation are investigated using nonlinear time history analyses (NLTHA) in buildings with 5%, 15% and 25% mass asymmetry with respect to the number of collapsed hinges and story drifts criteria. Results show that increasing the value of mass eccentricity makes the asymmetric buildings become unstable earlier and in the early stages with lower number of the collapsed hinges. So, with increasing the mass eccentricity in building, instability and collapse of the entire building occurs earlier, with lower potential of the progressive collapse. It is also demonstrated that with increasing the mass asymmetry the decreasing trend of the number of collapsed beam and column hinges is approximately similar to the decreasing trend in the average story drifts of the mass centers and stiff edges. So, as an alternative to a much difficult-to-calculate local response parameter of the number of collapsed hinges, the story drift, as a global response parameter, measures the potential of progressive collapse more easily.

Key Words
progressive collapse mechanism; asymmetric reinforced concrete buildings; earthquake load

Address
Somayyeh Karimiyan: Department of Earthquake Engineering, Taha University, Tehran, Iran

Ali Husseinzadeh Kashan: Department of Industrial Engineering, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran

Morteza Karimiyan: Applied Science and Technology University, Tehran, Iran

Abstract
The performance of passive control system for the seismic protection of a multi-tower cable-stayed bridge with the application of partially longitudinal constraint system is investigated. The seismic responses of the Jiashao Bridge, a six-tower cable-stayed bridge using the partially longitudinal constraint system are studied under real earthquake ground motions. The effects of the passive control devices including the viscous fluid dampers and elastic cables on the seismic responses of the bridge are examined by taking different values of parameters of the devices. Further, the optimization design principle of passive control system using viscous fluid dampers is presented to determine the optimized parameters of the viscous fluid dampers. The results of the investigations show that the control objective of the multi-tower cable-stayed bridge with the partially longitudinal constraint system is to reduce the base shears and moments of bridge towers longitudinally restricted with the bridge deck. The viscous fluid dampers are found to be more effective than elastic cables in controlling the seismic responses. The optimized parameters for the viscous fluid dampers are determined following the principle that the peak displacement at the end of bridge deck reaches to the maximum value, which can yield maximum reductions in the base shears and moments of bridge towers longitudinally restricted with the bridge deck, with slight increases in the base shears and moments of bridge towers longitudinally unrestricted with the bridge deck.

Key Words
multi-tower cable-stayed bridge; seismic response; viscous fluid damper; elastic cable; passive control system

Address
Geng Fangfang, Ding Youliang and Li Aiqun: Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, Southeast University, Nanjing 210096, China

Song Jianyong and Li Wanheng: Research Institute of Highway Ministry of Transport, Beijing 100088, China


Abstract
Current seismic codes (e.g. the NTC08 Italian code and the EC8 European code) adopt a performance-based approach for both the design of new buildings and the assessment of existing ones. Different limit states are considered by verifying structural members as well as non structural elements and facilities which have generally been neglected in practice. The key role of non structural elements on building performance has been shown by recent earthquakes (e.g. L\'Aquila 2009) where, due to the extensive damage suffered by infills, partitions and ceilings, a lot of private and public buildings became unusable with consequent significant socio-economic effects. Furthermore, the collapse of infill panels, particularly in the case of out-of-plane failure, represented a serious source of risk to life safety. This paper puts forward an infill model capable of accounting for the effects arising from prior in-plane damage on the out-of-plane capacity of infill panels. It permits an assessment of the seismic performance of existing RC buildings with reference to both structural and non structural elements, as well as of their mutual interaction. The model is applied to a building type with RC framed structure designed only to vertical loads and representative of typical Italian buildings. The influence of infill on building performance and the role of the out-of-plane response on structural response are also discussed.

Key Words
RC buildings; seismic assessment; masonry infills; out-of-plane behaviour; in-plane damage; seismic code

Address
V. Manfredi and A. Masi: School of Engineering, University of Basilicata, viale dell\'Ateneo Lucano, 85100 Potenza, Italy

Abstract
Shaking tables are devices for testing structures or structural components models with a wide range of synthetic ground motions or real recorded earthquakes. They are essential tools in earthquake engineering research since they simulate the effects of the true inertial forces on the test specimens. The destructive earthquakes that occurred at the north part of Algeria during the period of 1954-2003 resulted in an initiative from the Algerian authorities for the construction of a shaking simulator at the National Earthquake Engineering Research Center, CGS. The acceleration tracking performance and specifically the inability of the earthquake simulator to accurately replicate the input signal can be considered as the main challenge during shaking table test. The objective of this study is to validate the uni-axial sinusoidal performances curves and to assess the accuracy and fidelity in signal reproduction using the advanced adaptive control techniques incorporated into the MTS Digital controller and software of the CGS shaking table. A set of shake table tests using harmonic and earthquake acceleration records as reference/commanded signals were performed for four test configurations: bare table, 60 t rigid mass and two 20 t elastic specimens with natural frequencies of 5 Hz and 10 Hz.

Key Words
servohydraulic shaking table; MTS 469D controller; stex3.0 controller; adaptive control

Address
Hassan AKNOUCHE, Hakim BECHTOULA1b, Abdelhalim AIROUCHE: National Earthquake Engineering Research Center, CGS, Rue Kaddour Rahim Prolongée Bp 252 H-Dey Alger, Algeria

Hassan AKNOUCHE, Abdelhalim AIROUCHE and Djillali BENOUAR: University of Bab Ezzouar (USTHB), FGC/ Built Environment Res. Lab. (LBE) BP 32 El Alia, Bab Ezzouar, Alger 16111, Algeria

Abstract
After strong earthquakes conventional frames used worldwide in multi - story steel buildings (e.g. moment resisting frames) are not well positioned according to reparability. Two innovative systems for seismic resistant steel frames incorporated with dissipative fuses were developed within the European Research Program

Key Words
innovative; seismic; systems; fuses; beams

Address
Georgia Dougka, Danai Dimakogianni and Ioannis Vayas: School of Civil Engineering, National Technical University of Athens,
Iroon Polytechniou 9, 15772 Zografou, Greece


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