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CONTENTS
Volume 10, Number 3, March 2016
 

Abstract
Ancient monuments of Greek and Roman classical architecture usually consist of multi-drum columns that are constructed of stone blocks placed on top of each other. Several research studies deal with the seismic behaviour of such structures, since earthquakes are common causes of destruction of such monuments. This paper investigates the effect of multiple earthquakes on the seismic performance of multidrum columns, through numerical simulations and parametric analyses. The Discrete Element Method and an appropriate contact model have been implemented in a specially developed software application that is able to efficiently perform the necessary simulations in two dimensions. Specifically, various strong ground excitations are used in series for the computation of the collective final deformation of multi-drum columns. In order to calculate this cumulative deformation for a series of ground motions, the individual deformation of the column for each excitation is computed and then used as initial conditions for the next earthquake excitation. Various multi-drum columns with different dimensions are also considered in the analyses in order to examine how the geometric characteristics of columns can affect their seismic sequence behaviour, in combination with the excitation frequency content.

Key Words
ancient columns; rigid bodies; earthquake sequence; aftershock; rocking; discrete element method

Address
Loizos Papaloizou,Petros Komodromos: Department of Civil and Environmental Engineering, University of Cyprus, Nicosia, Cyprus

Panayiotis Polycarpou: Department of Engineering, University of Nicosia, Nicosia, Cyprus

George D. Hatzigeorgiou: School of Science and Technology, Hellenic Open University, Patras, Greece

Dimitri E. Beskos: Department of Civil Engineering, University of Patras, Patras, Greece

Abstract
Besides their spiritual significance, minarets are humanity´ s cultural heritage to the future generations due to their historical and architectural attraction. Currently, many historical masonry minarets are damaged and destroyed due to several reasons such as earthquakes and wind. Therefore, safety of these religiously significant buildings needs to be thoroughly investigated. The utmost care must be taken into account while investigating these structures. Our study investigated earthquake behavior of historical masonry minaret of Hac

Key Words
historical masonry minaret; dynamic characteristics; operational modal analysis; model calibration; seismic safety

Address
Hakan Başaran, Ali Demir,Halil Nohutçu, Celalettin Kozanoğlu: Department of Civil Engineering, Celal Bayar University, Manisa, Turkey

Emre Ercan: Department of Civil Engineering, Ege University, İzmir, Turkey

Emin Hökelekli: Bolvadin Vocational School, Afyon Kocatepe University, Afyon, Turkey

Abstract
The seismic behavior of a 1/2 scaled, three-story three-bay RC frame with masonry infill walls was studied experimentally and numerically. Pseudo-dynamic test results showed that despite following the column design provisions of modern seismic codes and neglecting the presence of infill walls, shear induced damage is unavoidable in the boundary columns. A finite element model was validated by using the results of available one-story one-bay frame tests in the literature. Simulations of the examined test frame demonstrated that boundary columns are subjected to shear demands in excess of their shear capacity. Seismic assessment of the test frame was conducted by using ASCE/SEI 41-06 (2006) guidelines and the obtained results were compared with the damage observed during experiment. ASCE/SEI 41-06 method for the assessment of boundary columns was found unsatisfactory in estimating the observed damage. Damage estimations were improved when the strain limits were used within the plastic hinge zone instead of column full height.

Key Words
pseudo-dynamic testing; masonry infill wall; finite element method; seismic assessment

Address
Aksel Fenerci: Department of Structural Engineering, Norwegian Univ. of Science and Tech., 7491, Trondheim, Norway

Baris Binici, Erdem Canbay: Department of Civil Engineering, Middle East Technical University, 06800 Ankara, Turkey

Pourang Ezzatfar, Guney Ozcebe: Department of Civil Engineering, TED University, 06420 Ankara, Turkey

Abstract
In this study, solution models are proposed to obtain code-compatible ground motion record sets which can be used for both uni-directional and bi-directional dynamic analyses. Besides scaled, unscaled ground motion record sets are obtained to show the utility and efficiency of the solution models. For scaled ground motion sets the proposed model is based on hybrid HS-Solver which integrates heuristic harmony search (HS) algorithm with the spreadsheet Solver add-in. For unscaled ground motion sets HS based solution model is proposed. Design spectra defined in Eurocode-8 for different soil types are selected as target spectra. The European Strong Motion Database is used to get ground motion record sets. Also, a sensitivity analysis is conducted to evaluate the effect of different HS solution parameters on the solution accuracy. Results show that the proposed solution models can be regarded as efficient ways to develop scaled and unscaled ground motion sets compatible with code-based design spectra.

Key Words
ground motion selection; harmony search algorithm; response history analysis

Address
Department of Civil Engineering, University of Pamukkale, Denizli, Turkey

Abstract
This paper presents an analytical study aimed at evaluating the seismic performance of steel moment resisting frames (MRFs) retrofitted with different approaches. For this, 3, 6 and 12 storey MRFs having four equal bays of 5 m were selected as the case study models. The models were designed with lateral stiffness insufficient to satisfy code drift and hinge limitations in zones with high seismic hazard. Three different retrofit strategies including traditional diagonal bracing system and energy dissipation devices such as buckling restrained braces and viscoelastic dampers were used for seismic upgrading of the existing structures. In the nonlinear time history analysis, a set of ground motions representative of the design earthquake with 10% exceedance probability in fifty years was taken into consideration. Considering the local and global deformations, the results in terms of inter-storey drift index, global damage index, plastic hinge formations, base shear demand and roof drift time history were compared. It was observed that both buckling-restrained braces and viscoelastic dampers allowed for an efficient reduction in the demands of the upgraded frames as compared to traditional braces.

Key Words
buckling-restrained brace; conventional brace; earthquake; viscoelastic damper; structural response; performance characteristics

Address
Department of Civil Engineering, Gaziantep University, 27310, Gaziantep, Turkey

Abstract
The effectiveness of the use of modern repair schemes for the seismic retrofit of existing RC structures were assessed on a comparative experimental study of carbon fiber-reinforced polymer (CFRP) strips and sheets for the repair of reinforced concrete members of RC frames, damaged because of cyclic loading. Two virgin, single - story, one - bay, 1/3 - scale frame specimens were tested under cyclic horizontal loading, up to a drift level of 4%. Then, virgin specimens, B and F, respectively, were repaired and retested in the same way. One, specimen RB, was repaired with epoxy injections and CFRP strips and one, specimen RF, was repaired with epoxy injections and CFRP sheets. The two specimens are used to examine the differences between the structural behavior of frames repaired using CFRP strips and frames repaired using CFRP sheets. Both qualitative and quantitative conclusions, based on the observed maximum loads, loading and reloading stiffness, hysteretic energy absorption and failure mechanisms are presented and compared. The repaired frames recovered their strength, stiffness and energy dissipated reasonably. The use of CFRP sheets was found more effective than CFRP strips, due to the proper anchorage.

Key Words
RC frames; seismic loading; rehabilitation; CFRP strips; CFRP sheets

Address
Department of Civil Engineering, Technological Educational Institution of Central Macedonia, Serres 62124, Greece

Abstract
Among all the natural disasters, earthquakes are the most destructive calamities since they cause a plenty of injuries and economic losses leaving behind a series of signs of panic. The present study highlights the moment-curvature relationships for the structural elements such as beam and column elements and Non-Linear Static Pushover Analysis of RC frame structures since it is a very simplified procedure of non-linear static analysis. The highly popular model namely Mander´s model and Kent and Park model are considered and then, seismic risk evaluation of RC building has been conducted using SAP 2000 version 17 treating uncertainty in strength as a parameter. From the obtained capacity and demand curves, the performance level of the structure has been defined. The seismic fragility curves were developed for the variations in the material strength and damage state threshold are calculated. Also the comparison of experimental and analytical results has been conducted.

Key Words
pushover analysis; moment-curvature relationship; Mander model; Kent and Park model; fragility analysis; damage state thresholds

Address
Nagashree B.K., Ravi Kumar C.M.: Department of Civil Engineering, Visvesvaraya Technological University B.D.T College of Engineering, Davangere, Karnataka, 577004, India

Venkat Reddy D.: Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, Mangalore,
Karnataka, 575025, India

Abstract
The 750 m long "De Bosset" bridge in the Cephalonia Island of Western Greece, being the area with the highest seismicity in Europe, was constructed in 1830 by successive stone arches and stiff blocktype piers. The bridge suffered extensive damages during past earthquakes, such as the strong M7.2 earthquake of 1953, followed by poorly-designed reconstruction schemes with reinforced concrete. In 2005, a multidisciplinary project for the seismic assessment and restoration of the "De Bosset" bridge was undertaken under the auspices of the Greek Ministry of Culture. The proposed retrofitting scheme combining soil improvement, structural strengthening and reconstruction of the deteriorated masonry sections was recently applied on site. Design of the rehabilitation measures and assessment of the pre- and post-interventions seismic response of the bridge were based on detailed in-situ and laboratory tests, providing foundation soil and structural material properties. In-situ inspection of the rehabilitated bridge following the strong M6.1 and M6.0 Cephalonia earthquakes of January 26th and February 3rd 2014, respectively, revealed no damages or visible defects. The efficiency of the bridge retrofitting is also proved by a preliminary performance analysis of the bridge under the recorded ground motion induced by the above earthquakes.

Key Words
retrofitting; "De Bosset" bridge; old stone masonry bridges; numerical analysis; micropiles; Cephalonia 2014 earthquakes

Address
Emmanouil N. Rovithis: Institute of Engineering Seismology and Earthquake Engineering (EPPO-ITSAK), Dasyliou Str., Elaiwnes, Pylaia, 55102, Thessaloniki, Greece

Kyriazis D. Pitilakis: Department of Civil Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece

Abstract
In this paper, the underground box structure is discretized as a system with limited freedoms, and the explosion seismic wave is regarded as series of dynamic force acting on the lumped masses. Based on the local deformation theory, the elastic resistances of the soil are simplified as the effects of numbers of elastic chain-poles. Matrix force method is adopted to analyze the deformation of the structure in elastic half space. The structural dynamic equations are established and by solving these equations, the axial force, the moment and the displacement of the structure are all obtained. The influences of size ratio, the incident angle and the rock type on the dynamic response of the underground box structure are all investigated through a case study by using the proposed method.

Key Words
explosion seismic wave; underground box structure; dynamic response; matrix force method

Address
Houxu Huang, Jie Li, Xiaoli Rong, Pengxian Fan: State Key Laboratory of Disaster prevention and Mitigation of Explosion and Impact, PLA University of Science and Technology, Nanjing, China

Shufang Feng: Institute of Engineering Research and Design, Headquarters of Shenyang Military Area, Shenyang, China

Abstract
The model of two-temperature magneto-thermoelasticity for a non-simple variable-thermalconductivity infinitely-long solid cylinder is established. The present cylinder is made of an isotropic homogeneous thermoelastic material and its bounding plane is traction-free and subjected to a timedependent temperature. An exact solution is firstly obtained in Laplace transform space to obtain the displacement, incremental temperature, and thermal stresses. The inversion of Laplace transforms has been carried out numerically since the response is of more interest in the transient state. A detailed analysis of the effects of phase-lags, an angular frequency of thermal vibration and the variability of thermal conductivity parameter on the field quantities is presented.

Key Words
thermoelasticity; phase-lags; non-simple; solid cylinder; variable thermal conductivity

Address
Ashraf M. Zenkour: Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia

Ashraf M. Zenkour: Department of Mathematics, Faculty of Science, Kafrelsheikh University, Kafr El-Sheikh 33516, Egypt

Ahmed E. Abouelregal: Department of Mathematics, Faculty of Science, Mansoura University, Mansoura 35516, Egypt

Ahmed E. Abouelregal: Department of Mathematics, College of Science and Arts, Aljouf University, El-Qurayat, Saudi Arabia

Abstract
Buckling-restrained braced frames (BRBFs) are commonly used as lateral force-resisting systems in the structures located in seismic-active regions. The nearly symmetric load-displacement behavior of buckling-restrained braces (BRBs) helps in dissipating the input seismic energy through metallic hysteresis. In this study, an experimental investigation has been conducted on the reduced-core length BRB (RCLBRB) specimens to evaluate their hysteretic and overall performance under gradually increased cyclic loading. Detachable casings are used for the concrete providing confinement to the steel core segments of all test specimens to facilitate the post-earthquake inspection of steel core elements. The influence of variable core clearance and the local detailing of casings on the cyclic performance of RCLBRB specimens has been studied. The RCLBRB specimen with the detachable casing system and a smaller core clearance at the end zone as compared to the central region exhibited excellent hysteretic behavior without any slip. Such RCLBRB showed balanced higher yielding deformed configuration up to a core strain of 4.2% without any premature instability. The strength-adjustment factors for the RCLBRB specimens are found to be nearly same as that of the conventional BRBs as noticed in the past studies. Simple expressions have been proposed based on the regression analysis to estimate the strength-adjustment factors and equivalent damping potential of the RCLBRB specimens.

Key Words
braced frames; buckling-restrained braces; component testing; energy dissipation; seismic response; yielding

Address
Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi-110016, India

Abstract
Trapezoidal Cemented Sand and Gravel Dam, namely Trapezoid CSG, is a new type of dam. Due to lack of dynamic studies in the field of CSG dam, this research was performed to analyze Trapezoidal CSG dam using dynamic Finite element method with ABAQUS Software. To investigate possible earthquake-induced damages, fragility curves are plotted based on damage index, the length of the cracks created at the dam base and the area of cracked elements in the dam. The seismic analysis indicated that minimum and maximum tensions are generated in the heel and toe of the dam, respectively. According to the fragility curves, with increase in PGA, the possibility of the exceeding the defined limit state is increased. However, the rate of increment is significantly reduced after PGA=0.4 g. Also, the same result is achieved for the second limit state. The "area of cracked elements" is more conservative criterion than the "crack length at the dam base", especially at PGA<0.4 g. As conclusion, CSG dams, despite of being made of poor materials in comparison with concrete dams, show good resistance, and even in some situations, better performance than the weighted concrete dams.

Key Words
CSG dam; numerical analysis; fragility curves; concrete damage plasticity; damage index; limit state

Address
Amir Arefian: Department of Civil Engineering, Science and Research branch, Islamic Azad University, Tehran, Iran

Ali Noorzad: Department of Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran

Mohsen Ghaemian: Civil Engineering Department, Sharif University of Technology, Tehran, Iran

Abbas Hosseini: Department of Civil Engineering, Science and Research branch, Islamic Azad University, Tehran, Iran


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