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CONTENTS
Volume 22, Number 5, May 2022
 

Abstract
One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

Key Words
concrete pipe; dynamic analysis; earthquake load; fluid force; numerical method

Address
Yanbing Liu:Beijing Earthquake Agency, Beijing 100080, China

Mohamed Amine Khadimallah:1)Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, Al-Kharj, 16273, Saudi Arabia
2)Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia

Amir Behshad:Faculty of Technology and Mining, Yasouj University, Choram 75761-59836, Iran

Abstract
In this article, wave propagation in functional gradation plates (FG) resting on an elastic foundation with two parameters is studied using a new quasi-three-dimensional (3D) higher shear deformation theory (HSDT). The new qausi-3D HSOT has only five variables in fields displacement, which means has few numbers of unknowns compared with others quasi3D. This higher shear deformation theory (HSDT) includes shear deformation and effect stretching with satisfying the boundary conditions of zero traction on the surfaces of the FG plate without the need for shear correction factors. The FG plates are considered to rest on the Winkler layer, which is interconnected with a Pasternak shear layer. The properties of the material graded for the plates are supposed to vary smoothly, with the power and the exponential law, in the z-direction. By based on Hamilton's principle, we derive the governing equations of FG plates resting on an elastic foundation, which are then solved analytically to obtain the dispersion relations. Numerical results are presented in the form of graphs and tables to demonstrate the effectiveness of the current quasi-3D theory and to analyze the effect of the elastic foundation on wave propagation in FG plates.

Key Words
dynamics responses advanced composite plates; quasi-3D theory; variables elastic foundations

Address
Riadh Bennai:1)Department of Civil Engineering, Faculty of Civil Engineering and Architecture, University Hassiba Benbouali of Chlef, Algeria
2)Laboratory of Structures, Geotechnics and Risks, Department of Civil Engineering, Hassiba Benbouali University of Chlef, Algeria

Fatma Mellal:1)Laboratory of Structures, Geotechnics and Risks, Department of Civil Engineering, Hassiba Benbouali University of Chlef, Algeria
2)Department of Technology, Faculty of Science and Technology, Djilali Bounaama University, Khemis Miliana, Algeria

Mokhtar Nebab:1)Laboratory of Structures, Geotechnics and Risks, Department of Civil Engineering, Hassiba Benbouali University of Chlef, Algeria
2)Department of Civil Engineering, Faculty of Sciences, University of M'Hamed BOUGARA Boumerdes, Algeria

Hocine Fourn:Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria

Mourad Benadouda:Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria

Hassen Ait Atmane:1)Department of Civil Engineering, Faculty of Civil Engineering and Architecture, University Hassiba Benbouali of Chlef, Algeria
2)Laboratory of Structures, Geotechnics and Risks, Department of Civil Engineering, Hassiba Benbouali University of Chlef, Algeria

Abdelouahed Tounsi:1)Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
2)YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea
3)Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran,
Eastern Province, Saudi Arabia

Muzamal Hussain:Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan



Abstract
Energy-saving block and invisible multiribbed frame composite wall (EBIMFCW) is an important shear wall, which is composed of energy-saving blocks, steel bars and concrete. This paper conducted seismic performance tests on six 1/2- scale EBIMFCW specimens, analyzed their failure process under horizontal reciprocating load, and studied the effect of axial compression ratio on the wall's hysteresis curve and skeleton curve, ductility, energy dissipation capacity, stiffness degradation, bearing capacity degradation. A formula for calculating the peak bearing capacity of such walls was proposed. Results showed that the EBIMFCW had experienced a long time deformation from cracking to failure and exhibited signs of failure. The three seismic fortification lines of the energy-saving block, internal multiribbed frame, and outer multiribbed frame sequentially played important roles. With the increase in axial compression ratio, the peak bearing capacity and ductility of the wall increased, whereas the initial stiffness decreased. The change in axial compression ratio had a small effect on the energy dissipation capacity of the wall. In the early stage of loading, the influence of axial compression ratio on wall stiffness and strength degradation was unremarkable. In the later stage of loading, the stiffness and strength degradation of walls with high axial compression ratio were low. The displacement ductility coefficients of the wall under vertical pressure were more than 3.0 indicating that this wall type has good deformation ability. The limit values of elastic displacement angle under weak earthquake and elastic-plastic displacement angle under strong earthquake of the EBIMFCW were1/800 and 1/80, respectively.

Key Words
axial compression ratio; EBIMFCW; hysteretic curve; shear wall; seismic performance

Address
Sheng-cai Li:School of Civil Engineering, Putian University, Southeast Coast Engineering Structure Disaster Prevention and Reduction Engineering
Research Center of Fujian Province University (JDGC03), Putian 351100, Fujian, China

Qiang Lin:School of Civil Engineering, Huaqiao University, Xiamen 361021, Fujian, China

Abstract
This paper presents a comparative experimental study on structural behavior of the interlocking masonry walls under in-plane cyclic loading. The main purpose of this study is to increase lateral load-bearing capacities of masonry walls by using interlocking units. The interlocking units were designed by considering failure modes of masonry walls and produced using lightweight foamed concrete. To this end, three masonry walls which are hollow, fully grouted, and reinforced were constructed with interlocking units. Also, a traditional masonry brick wall was built for comparison reasons. The walls were tested under in-plane cyclic loading. Then, structural parameters of the walls such as lateral load bearing and total energy dissipation capacities, ductility, stiffness degradation as well as failure modes obtained from the test were compared with each other. The results have shown that the walls with the interlocking units have better structural performance than traditional masonry brick walls and they may be used in the construction of low-rise masonry structures in rural areas to improve in-plane structural performance.

Key Words
in-plane behavior; interlocking masonry; mortared joints; masonry structures; structural parameters

Address
Fatma Birinci Kayaalp and Metin Hüsem: Department of Civil Engineering, Karadeniz Technical University, Trabzon, Turkey

Abstract
China is prone to earthquake disasters, and the higher seismic performance is required by many existing civil buildings. And seismic evaluation and retrofit are effective measures to mitigate seismic hazards. With the development of performance-based seismic design and diverse retrofit technology for buildings, advanced evaluation methods and retrofit strategies are in need. In this paper, we introduced the evolution of seismic performance objectives in China combined with performance-based seismic design. Accordingly, multi-phase evaluation methods and comprehensive seismic capacity assessment are introduced. For buildings with seismic deficiency or higher performance requirements, the retrofit technologies are categorized into three types: component strengthening, system optimization, and passive control. Both engineering property and social property for the retrofit methods are discussed. The traditional seismic retrofit methods usually are costly and disturbing, and for example in Beijing, seismic strengthening costs approx. 1000 RMB/m2 (for 160 USD/m2 ), for hospital building even more expensive as 5000 RMB/m2 (for 790 USD/m2 ). So cost-efficient and little disturbance methods are promising techniques. In the end, some opinions about the retrofit strategy and schemes category are shared and wish to discuss the situation and future of seismic retrofit in China.

Key Words
advanced retrofit strategy; code evolution; existing building; performance-based seismic evaluation; practical retrofit techniques

Address
Hao Wang, Baitao Sun and Hongfu Chen:1)Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics,
China Earthquake Administration, Harbin 150080, China
2)Key Laboratory of Earthquake Disaster Mitigation, Ministry of Emergency Management, Harbin 150080, China

Abstract
This paper presents the development of seismic fragility curves for a precast reinforced concrete bridge instrumented with a structural health monitoring (SHM) system. The bridge is located near an active seismic fault in the Dominican Republic (DR) and provides the only access to several local communities in the aftermath of a potential damaging earthquake; moreover, the sample bridge was designed with outdated building codes and uses structural detailing not adequate for structures in seismic regions. The bridge was instrumented with an SHM system to extract information about its state of structural integrity and estimate its seismic performance. The data obtained from the SHM system is integrated with structural models to develop a set of fragility curves to be used as a quantitative measure of the expected damage; the fragility curves provide an estimate of the probability that the structure will exceed different damage limit states as a function of an earthquake intensity measure. To obtain the fragility curves a digital twin of the bridge is developed combining a computational finite element model and the information extracted from the SHM system. The digital twin is used as a response prediction tool that minimizes modeling uncertainty, significantly improving the predicting capability of the model and the accuracy of the fragility curves. The digital twin was used to perform a nonlinear incremental dynamic analysis (IDA) with selected ground motions that are consistent with the seismic fault and site characteristics. The fragility curves show that for the maximum expected acceleration (with a 2% probability of exceedance in 50 years) the structure has a 62% probability of undergoing extensive damage. This is the first study presenting fragility curves for civil infrastructure in the DR and the proposed methodology can be extended to other structures to support disaster mitigation and post-disaster decision-making strategies.

Key Words
civil infrastructure; digital twins; earthquake engineering; fragility curves; structural health monitoring

Address
Norberto Rojas-Mercedes:School of Engineering, Instituto Tecnológico de Santo Domingo (INTEC), Santo Domingo, Dominican Republic

Kalil Erazo:1)School of Engineering, Instituto Tecnológico de Santo Domingo (INTEC), Santo Domingo, Dominican Republic
2)Department of Civil and Environmental Engineering, Rice University, Houston, Texas, USA

Luigi Di Sarno:


Abstract
In this paper, nonlinear P-delta effects are studied on the seismic performance, and the modal responses of a flexural frame, considering large deformations. Using multiple scales method, the nonlinear differential equations of motion are estimated, and the nonlinear interactions between the frame's degrees of freedom are outcropped. The results of time and frequency domain analyzes of a dynamic model are examined under internal resonance cases, and the linear and nonlinear responses are investigated in each modal cases. Also, changing the modal responses with respect to the amplitude and frequency of the harmonic forces is evaluated. It is shown that the dominant absorption of energy is in the first natural frequency of the frame, in the case of earthquake excitation, and when a harmonic force is applied to the frame, the peaks of the frequency domain responses depending on the frequency of harmonic force are in the first, and second or third natural frequency of the structure.

Key Words
flexural frame; multiple scales method; nonlinear interaction; P-delta effect

Address
Dana Afshar and Majid Amin Afshar:Department of Technology and Engineering, Imam Khomeini International University P.O. Box 34149-16818, Qazvin, Iran

Abstract
In this paper the free vibration frequencies of tri-directional functionally graded materials imperfect plate is investigated for Several plate geometries with two types of porosity (even and uneven) and different type of material configuration. The effect of several parameters such as power law index and boundary conditions have been investigated. For this purpose, an efficient computational method is developed and written under Matlab environment, based on a threedimensional modeling and the isogeometric method is used for the discretization of the structure based on NURBS (Nonuniform rational B-spline) basis functions. The results obtained by the present method are validated by the comparison with the results given by several authors in the literature.

Key Words
free vibration; isogeometric analysis; multi-directional functionally graded materials; porosity

Address
Abdelhafid Lahdiri:Laboratory of Solid Mechanics and Systems, University of M

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