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CONTENTS
Volume 17, Number 3, September 2019
 

Abstract
An experimental study was conducted to evaluate the dynamic behavior of a free-standing frame equipped with a movable base system using cast iron and mortar as the bearing materials. The preliminary friction test indicated that a graphite layer developed on the interface and exhibited stable friction behavior. The friction coefficient ranged from 0.33 to 0.36 when the applied normal compression stress ranged from 2.6 to 5.2 MPa. The effect of the variation of normal compression stress would be small. Shaking table tests on the free-standing frame showed that rock, slide, and rock-slide responses occurred. The cumulative slide distance reached 381 mm under JMA Kobe wave excitation; however, only a few cyclic slides occurred at the same locations along the moving track. Most surfaces sustained single slides. Similar results can be observed in other shaking conditions. The insufficient cyclic sliding and significant rocking resulted in a few graphite layers on the mortar surfaces. Friction coefficients were generally similar to those obtained in the preliminary friction tests; however, the values fluctuated when the rocking became significant. The collisions due to rocking caused strong horizontal acceleration responses and resulted in high friction coefficient. In addition, the strong horizontal acceleration responses caused by the collisions made the freestanding specimen unable to reduce the input horizontal acceleration notably, even when slippage occurred. Compared with the counterpart fixed-base specimen, the specimen equipped with the iron-mortar base could reduce the horizontal acceleration amplification response and the structural deformation, whereas the vertical acceleration response was doubled due to collisions from rocking.

Key Words
friction coefficient; slide; movable base; mortar; cast iron; steel frame; shaking table test

Address
Yu-Lin Chung, Kuan-Ting Kuo: Department of Architecture, National Cheng Kung University, 701, No.1, University Road, Tainan City, Taiwan
Takuya Nagae: Department of Architecture, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
Koichi Kajiwara: Hyogo Earthquake Engineering Research Center, National Research Institute for Earth Science and Disaster Resilience, 1501-21, Nishikameya, Mitsuda, Shijimi-cho, Miki, Hyogo, 673-0515, Japan

Abstract
The purpose of this work is to analyze the bending behavior of laminated composite plates using the refined four-variable theory and the finite element method approach using an ANSYS 12 computational code. The analytical model is based on the multilayer plate theory of shear deformation of the nth-order proposed by Xiang et al 2011 using the theory principle developed by Shimpi and Patel 2006. Unlike other theories, the number of unknown functions in the present theory is only four, while five or more in the case of other theories of shear deformation. The formulation of the present theory is based on the principle of virtual works, it has a strong similarity with the classical theory of plates in many aspects, it does not require shear correction factor and gives a parabolic description of the shear stress across the thickness while filling the condition of zero shear stress on the free edges. The analysis is validated by comparing results with those in the literature.

Key Words
laminated; bending; refined nth-order shear deformation theory; finite element method

Address
Mokhtar Bouazza: Department of Civil Engineering, University Tahri Mohamed of Bechar, Bechar 08000, Algeria; Laboratory of Materials and Hydrology (LMH), University of Sidi Bel Abbes, Sidi Bel Abbes 2200, Algeria
Tawfiq Becheri, Abderrahmane Bouchetaand: Department of Civil Engineering, University Tahri Mohamed of Bechar, Bechar 08000, Algeria
Noureddine Benseddiq: Mechanics Laboratory of Lille, CNRS UMR 8107, University of Lille 1, 59655 Villeneuve d\'Ascq, France

Abstract
Knowing the response of buildings to earthquakes is very important in order to ensure that a structure is able to withstand a given level of ground shaking. Thus, nonlinear dynamic earthquake engineering analyses are unavoidable and are preferable procedure in the seismic assessment of buildings. In order to estimate seismic performance on the basis of the hazard at the site where the structure is located, the selection of appropriate seismic input is known to be a critical step while performing this kind of analysis. In this paper, seismic analysis is performed for a four-story reinforced concrete ISPRA frame structure which is designed according to Eurocode 8 (EC8). A total of 90 different earthquake scenarios were selected, 30 for each of three target spectrums, EC8 spectrum, Uniform Hazard Spectrum (UHS), and Conditional Mean Spectrum (CMS). The aim of this analysis was to evaluate the average maximum Inter-story Drift Ratio (IDR) for each target spectrum. Time history analysis for every earthquake record was obtained and, as a result, IDR as the main measure of damage were presented in order to compare with defined performance levels of reinforced concrete bare frames.

Key Words
seismic damage assessment; target spectrum; earthquake records

Address
Kristina Strukar, Tanja Kalman Sipos: Department for technical mechanics, Faculty of Civil Engineering and Architecture Osijek, Vladimira Preloga 3, HR31000 Osijek, Republic of Croatia
Mario Jelec, Marijana Hadzima-Nyarko: Department for materials and constructions, Faculty of Civil Engineering and Architecture Osijek, Vladimira Preloga 3, HR31000 Osijek, Republic of Croatia

Abstract
During the seismic performance assessment of existing buildings, staircases are generally not taken into account as structural members but as dead load. Staircases, as secondary structural members, not only serve for connecting successive floors but also provide considerable amount of strength and stiffness to the building which can modify its seismic behaviour considerably. In this parametric study, the influence of staircases on the seismic response of substandard RC frame buildings which differ in number of storey and span, presence of staircase and its position has been examined. Modal Analyses and bidirectional Non-Linear Time History Analyses (NLTHA) were conducted to compare several engineering demand parameters (EDPs) such as inter-storey drift ratio (ISDR), floor accelerations, modal properties, member shear forces and plastic hinge distribution. Additionally, short column effect, variation in shear forces of columns that are attached to the staircase slab, failure and deformation in staircase models have also been investigated. As the staircase was considered in the analytical model, a different damage pattern can be developed especially in the structural components close to staircase.

Key Words
substandard; RC frame; staircase; short column; seismic

Address
Ayberk Karaaslan: Department of Civil Engineering, Uludag University, Bursa, Turkey
Ozgür Avsar: Department of Civil Engineering, Eskişehir Technical University, Eskişehir, Turkey

Abstract
The extension of existing RC buildings is a challenging process, which requires efficient connection between existing and new materials to guarantee load transferring between the lap-spliced longitudinal columns\' reinforcement. Therefore, the length of the columns\' starter bars is a crucial factor, which decisively affects the seismic response of the new columns. In particular, when the length of the starter bars is short, then the length of the lap splices of reinforcement is inadequate to ensure load transfer between steel bars and concrete, with an indisputable detrimental impact on the seismic behaviour of the columns. Moreover, in most of the existing RC buildings the column starter bars are of particularly short length, while they have probably been bent, cut or corroded. In the present study, the effectiveness of both welded rebar and mechanical splices of reinforcement in ensuring load transferring between the starter bars and the longitudinal reinforcement of the new column was experimentally evaluated. Four cantilever column subassemblages were constructed and subjected to earthquaketype loading. Three of the specimens were used to examine different types of shielded metal arc welding (SMAW), while in the fourth subassemblage mechanical splices were tested. The hysteretic response of the columns was evaluated and compared to the behaviour of a fifth specimen with continuous reinforcement, tested by Kalogeropoulos and Tsonos (2019). Test results clearly demonstrated that the examined types of SMAW were equally satisfactory in ensuring the ductile seismic performance of the columns, while the mechanical splices found to be more susceptible to exhibit slipping of the bars.

Key Words
RC columns; rebar; welding; mechanical splices of reinforcement

Address
George I. Kalogeropoulos, Alexander-Dimitrios G. Tsonos: Department of Civil Engineering, Aristotle University of Thessaloniki, GR-54-124 Thessaloniki, Greece
Dimitrios Konstantinidis: Department of Civil Engineering T.E., Alexander Technological Educational Institute of Thessaloniki, GR-57-400, Greece

Abstract
Building prediction and control theory have been drawing the attention of many scientists over the past few years because design and control efficiency consumes the most financial and energy. In the literature, many methods have been proposed to achieve this goal by trying different control theorems, but all of these methods face some problems in correctly solving the problem. The Evolutionary Bat (EB) Algorithm is one of the recently introduced optimization methods and providing researchers to solve different types of optimization problems. This paper applies EB to the optimization of building control design. The optimized parameter is the input to the fuzzy controller, which gives the status response as an output, which in turn changes the state of the associated actuator. The novel control criterion for guarantee of the stability of the system is also derived for the demonstration in the analysis. This systematic and simplified controller design approach is the contribution for solving complex dynamic engineering system subjected to external disturbances. The experimental results show that the method achieves effective results in the design of closed-loop system. Therefore, by establishing the stability of the closed-loop system, the behavior of the closed-loop building system can be precisely predicted and stabilized.

Key Words
intelligent control; system design; fuzzy theory; bat algorithm; fuzzy optimization

Address
Tim Chen: AI LAB, Faculty of Information Technology, Ton Duc Thang University, Ho Chi Minh City, Vietnam
Alex Bird: National Physical Laboratory, New Delhi, Dr KS Krishnan Marg, Pusa, New Delhi, Delhi 110012, India
John Mazhar Muḥammad: Computer Simulation Research Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PJ UK
S. Bhaskara Cao: National University of Sciences and Technology (NUST), School of Natural Sciences, H-12, Islamabad
Charles Melvilled : National University of Sciences and Technology (NUST), School of Natural Sciences, H-12, Islamabad
C.Y.J. Cheng: Department of Automatic Control, University of Southern Queensland, Darling Heights, TOOWOOMBA QLD 4350, Australia

Abstract
High-speed railway bridge piers in seismically active area may be subjected to multiple earthquakes and then produce cumulative residual deformation. To study the cumulative residual deformation of high-speed railway bridge piers under multiple earthquakes, a nonlinear numerical analytical model with multi-DOF (MDOF) system is presented and validated against two shaking table tests in this paper. Based on the presented model, a simple supported beam bridge pier model of highspeed railway is established and used to investigate the cumulative residual deformation of high-speed railway bridge pier under mainshock-aftershock sequences and swarm type seismic sequences. The results show that the cumulative residual deformation of the bridge pier increases with earthquake number, and the increasing rates are different under different earthquake number. The residual deformation of bridge pier subjected to multiple earthquakes is accumulated and may exceed the limit of code.

Key Words
high-speed railway bridge piers; multiple earthquakes; cumulative residual deformation; nonlinear numerical analytical model with multi-DOF

Address
Hongye Gou: Department of Bridge Engineering, School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China; Key Laboratory of High-Speed Railway Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
Dan Leng, Longcheng Yang and Hongyu Jia: Department of Bridge Engineering, School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China

Abstract
An efficient shear deformation beam theory is developed for thermo-elastic vibration of FGM beams. The theory accounts for parabolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the on the surfaces of the beam without using shear correction factors. The material properties of the FGM beam are assumed to be temperature dependent, and change gradually in the thickness direction. Three cases of temperature distribution in the form of uniformity, linearity, and nonlinearity are considered through the beam thickness. Based on the present refined beam theory, the equations of motion are derived from Hamilton\'s principle. The closed-form solutions of functionally graded beams are obtained using Navier solution. Numerical results are presented to investigate the effects of temperature distributions, material parameters, thermal moments and slenderness ratios on the natural frequencies. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

Key Words
thermo-elastic vibration; functionally graded materials; Hamilton

Address
Abdelkader Safa: 1Department of Civil Engineering, Ahmed Zabana University Centre, Relizane, 48000, Algeria; Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department,
Sidi Bel Abbes, Algeria
Lazreg Hadji: Department of Mechanical Engineering, Ibn Khaldoun University, BP 78 Zaaroura, 14000, Tiaret, Algeria; Laboratory of Geomatics and Sustainable Development, Ibn Khaldoun University of Tiaret, Algeria
Mohamed Bourada: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Sidi Bel Abbes, Algeria
Nafissa Zouatnia: Department of Civil Engineering, Ibn Khaldoun University, BP 78 Zaaroura, Tiaret, 14000, Algeria

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