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CONTENTS
Volume 35, Number 2, April25 2020
 

Abstract
Sandwich composite wall consists of concrete core attached by two external steel faceplates. It combines the advantage of steel and concrete. The appropriate composite action between steel faceplate and concrete core is achieved by using adequate mechanical connectors. This research studied the compressive behavior of the sandwich composite walls using steel trusses to bond the steel faceplates to concrete infill. Four short specimens with different wall width and thickness of steel faceplate were designed and tested under axial compression. The test results were comprehensively evaluated in terms of failure modes, load versus axial and lateral deformation responses, resistance, stiffness, ductility, strength index, and strain distribution. The test results showed that all specimens exhibited high resistance and good ductility. Truss connectors offer better restraint to walls with thinner faceplates and smaller wall width. In addition, increasing faceplate thickness is more effective in improving the ultimate resistance and axial stiffness of the wall.

Key Words
sandwich composite; truss connector; compression; structural behavior

Address
Ying Qin: Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, Southeast University, Nanjing, China;
School of Civil Engineering, Southeast University, Nanjing, China
Xin Chen, Xingyu Zhu, Wang Xi and Yuanze Chen: School of Civil Engineering, Southeast University, Nanjing, China

Abstract
This paper aims at providing insights on the use of thermosetting liner for the repair of offshore pipelines exposed to corrosion and leakage. The work which covers both experimental and numerical approaches were aspired due to the high cost of repair for pipelines, limitations of thermoplastic material and limited study of reinforced thermosetting liner. The experiment involves a destruction test called the burst test, carried out on an API 5L X42 carbon steel pipe under four case studies, namely (i) intact pipe, (ii) pipe with corrosion defect, (iii) pipe with corrosion defect and repaired with thermosetting liner and (iv) pipe with leakage and repaired with thermosetting liner. The numerical simulation was developed to first validate the experimental results and later to optimize the design of the thermosetting liner in terms of the number of layers required to restore the original strength of the pipe. The burst test shows an improvement in 23% of the burst capacity for the pipe with corrosion defects, after being repaired with a three-layer thermosetting liner. The parametric studies conducted showed that with an addition of thermosetting layers, the burst capacity improves by an average of 1.85 MPa. In conclusions, the improvement in strength can be further increased with increasing thickness of the thermosetting liner. The thermosetting liner was also determined to fail first inside the host pipe.

Key Words
pipeline; corrosion; leakage; burst capacity; repair; thermosetting liner

Address
Ali Akram and Zahiraniza Mustaffa: Department of Civil and Environmental Engineering, Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak, Malaysia
Thar M. Badri Albarody: Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak, Malaysia

Abstract
Ground motion records are commonly used for fragility curves (FCs) developing utilized in seismic loss estimating analysis for earthquake prone zones. These records could be \'real\', say the recorded acceleration time series or \'simulated\' records consistent with the regional seismicity and produced by use of alternative simulation methods. This study has focused on fragility curves developing for masonry buildings through computational \'simulated\' ground motion records while evaluating the properness of these fragilities compared to the curves generated by the use of \'real\' records. Assessing the dynamic responses of structures, nonlinear computational time history analyses through the equivalent single degree of freedom systems have been implemented on OpenSees platform. Accordingly, computational structural analyses of multi-story 3D frame structures with different stiffening members considering soil interaction have been carried out with finite element software according to (1992) Earthquake East-West component. The obtained results have been compared to each frame regarding soil interaction. Conclusion and recommendations with the discuss of obtaining findings are presented.

Key Words
ground motion; masonry buildings; soil Interaction; 3D frame structure; finite element

Address
Abdulaziz Alaskar and Fahed Alrshoudi: Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11362, Saudi Arabia
Karzan Wakil: Research Center, Sulaimani Polytechnic University, Sulaimani 46001, Kurdistan Region, Iraq;
Department of Computer, College of Science, University of Halabja, Halabja 46018, Kurdistan Region, Iraq
Rayed Alyousef, Hisham Alabduljabbar and Abdeliazim Mustafa Mohamed: Department of Civil Engineering, College of Engineering, Prince Sattam bin Abdulaziz University, Al-kharj 11942, Saudi Arabia
Kittisak Jermsittiparsert: Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Vietnam;
Faculty of Social Sciences and Humanities, Ton Duc Thang University, Ho Chi Minh City, Vietnam
Lanh Si Ho: Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam



Abstract
This paper proposes a Global-Local Analysis Method (GLAM) to assess the progressive collapse of steel framed structures under fire-induced column failure. GLAM obtains the overall structural response by combining dynamic analysis of the heated column (local) with static analysis of the overall structure (global). Test results of two steel frames which explicitly consider the dynamic effect during fire-induced column failure were employed to validate the proposed GLAM. Results show that GLAM gives reasonable predictions to the test frames in terms of both whether to collapse and the displacement verse temperature curves. Besides, several case studies of a two-dimensional (2D) steel frame and a three-dimensional (3D) steel frame with concrete slabs were conducted by using GLAM. Results show that GLAM gives the same collapse predictions to the studied cases with nonlinear dynamic analysis of the whole structure model. Compared with nonlinear dynamic analysis of the whole structure model, GLAM saves approximately 70% and 99% CPU time for the cases of 2D and 3D steel frame, respectively. Results also show that the load level of a structure has notable effects on the restraint condition of a heated column in the structure.

Key Words
steel framed structure; progressive collapse; robustness assessment method; fire-induced column failure; dynamic effect

Address
Binhui Jiang: School of Civil Engineering, Central South University, 68 South Shaoshan Road, Changsha 410075, China;
Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China
Guo-Qiang Li: College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China;
State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China
Michael C.H. Yam: Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China



Abstract
Cracks and defects may occur anywhere in a plate under tension. Cracks can affect the buckling stability performance and even the failure mode of the plate. A search of the literature reveals that the reported research has mostly focused on the study of plates with central and small cracks. Considering the effectiveness of cracks on the buckling behavior of plates, this study intends to investigate the effects of some key parameters, i.e., crack size and location as well as the plate aspect ratio and support conditions, on the buckling behavior, stress intensity factor (SIF), and the failure mode (buckling or fracture) in cracked plates under tension. To this end, a sophisticated mathematical code was developed using MATLAB in the frame-work of extended finite element method (XFEM) in order to analyze the buckling stability and collapse of numerous plate models. The results and findings of this research endeavor show that, in addition to the plate aspect ratio and support conditions, careful consideration of the crack location and size can be quite effective in buckling behavior assessment and failure mode prediction as well as SIF evaluation of the cracked plates subjected to tensile loading.

Key Words
cracked plates; tensile loading; buckling; stress intensity factor; extended finite element method

Address
Parham Memarzadeh, Sayedmohammad Mousavian and Mohammad Hosseini Ghehi: Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
Tadeh Zirakian: Department of Civil Engineering and Construction Management, California State University, Northridge, CA, USA

Abstract
Shear connectors are essential elements in the design of steel-concrete composite systems. These connectors are utilized to prevent the occurrence of potential slips at the interface of steel and concrete. The two types of shear connectors which have been recently employed in construction projects are C- and L-shaped connectors. In the current study, the behavior of C and L-shaped angle shear connectors is investigated experimentally. For this purpose, eight push-out tests were composed and subjected to monotonic loading. The load-slip curves and failure modes have been determined. Also, the shear strength of the connectors has been compared with previously developed relationships. Two failure modes of shear connectors were observed: 1) concrete crushing–splitting and 2) shear connector fracture. It was found that the L-shaped connectors have less shear strength compared to C-shaped connectors, and decreasing the angle leg size increases the shear strength of the C-shaped connectors, but decreases the relative ductility and strength of L-shaped connectors.

Key Words
composite beams; shear connector; C-shaped angle; L-shaped angle; push-out test; monotonic loading

Address
Mahdi Shariati: Division of Computational Mathematics and Engineering, Institute for Computational Science,
Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam;
Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam
Farzad Tahmasbi: Department of Civil Engineering, Sharif University of Technology, Tehran, Iran
Peyman Mehrabi: Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran
Alireza Bahadori: School of Civil Engineering, College of Engineering, University of Tehran, Iran
Ali Toghroli: Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam


Abstract
The main purpose of this research work is to investigate the free vibration of conical shell structures reinforced by graphene platelets (GPLs) and the elastic properties of the nanocomposite are obtained by employing Halpin-Tsai micromechanics model. To this end, a shell model is developed based on Donnell\'s theory. To solve the problem, the analytical Galerkin method is employed together with beam mode shapes as weighting functions. Due to importance of boundary conditions upon mechanical behavior of nanostructures, the analysis is carried out for different boundary conditions. The effects of boundary conditions, semi vertex angle, porosity distribution and graphene platelets on the response of conical shell structures are explored. The correctness of the obtained results is checked via comparing with existing data in the literature and good agreement is eventuated. The effectiveness and the accuracy of the present approach have been demonstrated and it is shown that the Donnell\'s shell theory is efficient, robust and accurate in terms of nanocomposite problems.

Key Words
Donnell\'s shell theory; porosity; Halpin-Tsai micromechanics model; conical structures; graphene platelets (GPLs)

Address
Kai Yan, Yao Zhang and Hao Cai: Key Lab of Building structural Retrofitting and Underground Space Engineering of the Ministry of Education,
Shandong Jianzhu University, Jinan, Shandong 251010, China
Vahid Tahouneh: Young Researchers and Elite Club, Islamshahr Branch, Islamic Azad University, Islamshahr, Iran


Abstract
In steel-concrete composite beams, to improve the cracking resistance of the concrete slab in the hogging moment region, a new type of connector in the interface, named uplift-restricted and slip-permitted screw-type (URSP-S) connector has been proposed. This paper focuses on the behavior of steel-concrete composite beams with URSP-S connectors. A total of three beam specimens including a simply supported beam with URSP-S connectors and two continuous composite beams with different connectors arrangements were designed and tested. More specifically, one continuous composite beam was equipped with URSP-S connectors in negative moment region and traditional shear studs in other regions. For comparison, the other one was designed with only traditional shear studs. The failure modes, crack evolution process, ultimate capacities, strain responses at different locations as well as the interface slip of the three tested specimens were measured and evaluated in-depth. Based on the experimental study, the research findings indicate that the larger slip deformation is allowed while using URSP-S connectors. Meanwhile, the tensile stress reduces and the cracking resistance of the concrete slab improves accordingly. In addition, the overall stiffness and strength of the composite beam become slightly lower than those of the composite beam using traditional shear studs. Moreover, the arrangement suggestion of URSP-S connectors in the composite beam is discussed in this paper for its practical design and application.

Key Words
steel-concrete composite beam; uplift-restricted and slip-permitted screw-type (URSP-S) connector; experimental study; cracking resistance; interface slip

Address
Linli Duan: College of Civil Engineering, Hunan University, Changsha 410082, China
Hongbing Chen: Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry,
Department of Civil Engineering, Tsinghua University, Beijing 100084, China
Xin Nie: Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry,
Department of Civil Engineering, Tsinghua University, Beijing 100084, China;
National Engineering Laboratory for Green and Safe Construction Technology in Urban Rail Transit,
Tsinghua University, Beijing 100084, China
Sanwei Han: Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry,
Department of Civil Engineering, Tsinghua University, Beijing 100084, China





Abstract
Foundation of a building is damaged under service loads during construction. First visit shows that the foundation has been punched at the 6 column\'s foot region led to building rotation. Foundation shear punching occurring has made some stresses and deflections in construction. In this study, progressing of damage caused by foundation shear punching and inverse loading in order to resolve the building rotation has been evaluated in the foundation and frame of building by finite element modeling in ABAQUS software. The stress values of bars in punched regions of foundation has been deeply exceeded from steel yielding strength and experienced large displacement based on software\' s results. On the other hand, the values of created stresses in the frame are not too big to make serious damage. In the beams and columns of ground floor, some partial cracks has been occurred and in other floors, the values of stresses are in the elastic zone of materials. Finally, by inverse loading to the frame, the horizontal displacement of floors has been resolved and the values of stresses in frame has been significantly reduced.

Key Words
shear punching; foundation; progressive collapse; inverse loading; ABAQUS

Address
Morteza Naghipour and Kia Moghaddas Niak: Department of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
Mahdi Shariati: Division of Computational Mathematics and Engineering, Institute for Computational Science,
Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam;
Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam
and Ali Toghroli: Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam


Abstract
This paper deals with free vibration analysis of non-uniform column resting on elastic foundations and subjected to follower force at its free end. The internal pores and graphene platelets (GPLs) are distributed in the matrix according to different patterns. The model is proposed with material parameters varying in the thickness of column to achieve graded distributions in both porosity and nanofillers. The elastic modulus of the nanocomposite is obtained by using Halpin-Tsai micromechanics model. The differential quadrature method as an efficient and accurate numerical approach is used to discretize the governing equations and to implement the boundary conditions. It is observed that the maximum vibration frequency obtained in the case of symmetric porosity and GPL distribution, while the minimum vibration frequency is obtained using uniform porosity distribution. Results show that for better understanding of mechanical behavior of nanocomposite column, it is crucial to consider porosities inside the material structure.

Key Words
columns; vibration; pores and graphene platelets; Halpin-Tsai micromechanics model; elastic foundation; Functionally Graded Materials (FGMs)

Address
Wen-qi Liu, Ming-yu Fan and Ji-peng Wang:School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu Sichuan, 611731, China
Shan-jun Liu: Key Lab of Information Network Security, Ministry of Public Security, Shanghai 201204, China
Wei Tian,:The 9533 troop of People\' s Liberation Army of China, Changsha Hunan 201204, China
Vahid Tahouneh: Young Researchers and Elite Club, Islamshahr Branch, Islamic Azad University, Islamshahr, Iran

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