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CONTENTS
Volume 34, Number 1, January10 2020
 

Abstract
This paper presents experimental and numerical studies on effects of local damages on the in-plane elastic-plastic buckling and strength of a fixed parabolic steel tubular arch under a vertical load distributed uniformly over its span, which have not been reported in the literature hitherto. The in-plane structural behaviour and strength of ten specimens with different local damages are investigated experimentally. A finite element (FE) model for damaged steel tubular arches is established and is validated by the test results. The FE model is then used to conduct parametric studies on effects of the damage location, depth and length on the strength of steel arches. The experimental results and FE parametric studies show that effects of damages at the arch end on the strength of the arch are more significant than those of damages at other locations of the arch, and that effects of the damage depth on the strength of arches are most significant among those of the damage length. It is also found that the failure modes of a damaged steel tubular arch are much related to its initial geometric imperfections. The experimental results and extensive FE results show that when the effective cross-section considering local damages is used in calculating the modified slenderness of arches, the column bucking curve b in GB50017 or Eurocode3 can be used for assessing the remaining in-plane strength of locally damaged parabolic steel tubular arches under uniform compression. Furthermore, a useful interaction equation for assessing the remaining in-plane strength of damaged steel tubular arches that are subjected to the combined bending and axial compression is also proposed based on the validated FE models. It is shown that the proposed interaction equation can provide lower bound assessments for the remaining strength of damaged arches under in-plane general loading.

Key Words
local damage; strength; steel arch; experimental investigation; remaining strength; finite element analysis (FEA)

Address
Yonghui Huang, Airong Liu and Jiyang Fu: Guangzhou University-Tamkang University Joint Research Center for Engineering Structure
Disaster Prevention and Control, Guangzhou University, Guangzhou 510006, China
Yong-Lin Pi: Guangzhou University-Tamkang University Joint Research Center for Engineering Structure
Disaster Prevention and Control, Guangzhou University, Guangzhou 510006, China;
Centre for Infrastructure Engineering and Safety (CIES), School of Civil and Environmental Engineering,
The University of New South Wales, Sydney, NSW 2052, Australia
Mark A. Bradford: Centre for Infrastructure Engineering and Safety (CIES), School of Civil and Environmental Engineering,
The University of New South Wales, Sydney, NSW 2052, Australia






Abstract
This paper investigates the flexural behavior of concrete beams reinforced longitudinally with either steel bars, molded glass-fiber reinforced polymer (GFRP) grating mesh or pultruded glass-fiber reinforced polymer (GFRP) grating mesh, under four-point bending. The variables included in this study were the type of concrete (normal weight concrete, perlite concrete and vermiculite concrete), type of the longitudinal reinforcement (steel bars, molded and pultruded GFRP grating mesh) and the longitudinal reinforcement ratio (between 0.007 and 0.035). The influences of these variables on the load-midspan deflection curves, bending stiffness, energy absorption and failure modes were investigated. A total of fifteen beams with a cross-sectional dimension of 160 mm X 210 mm and an overall length of 2400 mm were cast and divided into three groups. The first group was constructed with normal weight concrete and served as a reference concrete. The second and third groups were constructed with perlite concrete and vermiculite concrete, respectively. An innovative type of stirrup was used as shear reinforcement for all beams. The results showed that the ultimate load of the beams reinforced with pultruded GFRP grating mesh ranged between 19% and 38% higher than the ultimate load of the beams reinforced with steel bars. The bending stiffness of all beams was influenced by the longitudinal reinforcement ratio rather than the type of concrete. Failure occurred within the pure bending region which means that the innovative stirrups showed a significant resistance to shear failure. Good agreement between the experimental and the analytical ultimate load was obtained.

Key Words
molded GFRP grating; pultruded GFRP grating; expanded perlite; expanded vermiculite; energy absorption

Address
Muhammad N.S. Hadi, Mohammed H.A. Almalome, Tao Yu and William A. Rickards: School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia

Abstract
Integral abutment bridges (IABs) are those bridges without expansion joints. A single row of steel H-piles (SHPs) is commonly used at the thin and stub abutments of IABs to form a flexible support system at the bridge ends to accommodate thermal-induced displacement of the bridge. Consequently, as the IAB expands and contracts due to temperature variations, the SHPs supporting the abutments are subjected to cyclic lateral (longitudinal) displacements, which may eventually lead to low-cycle fatigue (LCF) failure of the piles. In this paper, the potential of using finite element (FE) modeling techniques to estimate the LCF life of SHPs commonly used in IABs is investigated. For this purpose, first, experimental tests are conducted on several SHP specimens to determine their LCF life under thermal-induced cyclic flexural strains. In the experimental tests, the specimens are subjected to longitudinal displacements (or flexural strain cycles) with various amplitudes in the absence and presence of a typical axial load. Next, nonlinear FE models of the tested SHP specimens are developed using the computer program ANSYS to investigate the possibility of using such numerical models to predict the LCF life of SHPs commonly used in IABs. The comparison of FE analysis results with the experimental test results revealed that the FE analysis results are in close agreement with the experimental test results. Thus, FE modeling techniques similar to that used in this research study may be used to predict the LCF life of SHP commonly used in IABs.

Key Words
Integral Abutment Bridge; Steel H-Pile; Low Cycle Fatigue; finite element simulation

Address
Memduh Karalar: Department of Civil Engineering, Bülent Ecevit University, Zonguldak, Turkey
Murat Dicleli: Department of Engineering Sciences, METU, 06800 Ankara, Turkey

Abstract
A novel all-steel miniature bar-type structural fuse (MBSF) with cold formed bolted connections is developed in this study, which consists of a central energy dissipation core cut from a smooth round bar, an external confining tube and nuts. Three types of cross sections for the central energy dissipation core, i.e., triple-cut, double-cut and single-cut cross sections, were studied. Totally 18 specimens were axially tested under either symmetric or asymmetric cyclic loading histories, where the parameters such as cut cross sectional area ratio, length of the yielding portion and cross sectional type were investigated. Numerical simulation of 2 representative specimens were also conducted. An analytical model to evaluate the bending failure at the elastic portion was proposed, and a design method to avoid this failure mode was also presented. The experimental results show that the proposed MBSFs exhibit satisfactory hysteretic performance under both the two cyclic loading histories. Average strain values of 8% and 4% are found to be respectively suitable for designing the new MBSFs as the ultimate strain under the symmetric and asymmetric cyclic loadings.

Key Words
structural fuses; quasi-triangular cross section; seismic performance; cyclic loading; steel

Address
Dongzhi Guan and Zhengxing Guo: School of Civil Engineering, Southeast University, Nanjing 211189, China;
Key Laboratory of Concrete and Pre-Stressed Concrete Structures of the Ministry of Education, Nanjing 211189, China
Sen Yang: Key Laboratory of Concrete and Pre-Stressed Concrete Structures of the Ministry of Education, Nanjing 211189, China
Liang-Jiu Jia: Department of Disaster Mitigation for Structures, Tongji University, Shanghai 200092, China


Abstract
The current paper illustrates the effect of in-plane varying compressive force on critical buckling loads and buckling modes of sandwich composite laminated beam rested on elastic foundation. To generalize a proposed model, unified higher order shear deformation beam theories are exploited through analysis; those satisfy the parabolic variation of shear across the thickness. Therefore, there is no need for shear correction factor. Winkler and Pasternak elastic foundations are presented to consider the effect of any elastic medium surrounding beam structure. The Hamilton\'s principle is proposed to derive the equilibrium equations of unified sandwich composite laminated beams. Differential quadrature numerical method (DQNM) is used to discretize the differential equilibrium equations in spatial direction. After that, eigenvalue problem is solved to obtain the buckling loads and associated mode shapes. The proposed model is validated with previous published works and good matching is observed. The numerical results are carried out to show effects of axial load functions, lamination thicknesses, orthotropy and elastic foundation constants on the buckling loads and mode shapes of sandwich composite beam. This model is important in designing of aircrafts and ships when non-uniform compressive load and shear loading is dominated.

Key Words
buckling stability; in-plane load function; sandwich beams; unified beam theories; elastic foundations; Differential Quadrature Method (DQM)

Address
Mostafa A. Hamed: Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, Saudi Arabia
Salwa A Mohamed: Department of Engineering Mathematics, Faculty of Engineering, Zagazig University,P.O. Box 44519, Zagazig, Egypt
Mohamed A. Eltaher: Mechanical Design & Production Department, Faculty of Engineering, Zagazig University,P.O. Box 44519, Zagazig, Egypt

Abstract
Steel-concrete composite beam with profiled steel sheet has gained its popularity in the last two decades. Due to the ageing of these structures, retrofitting in terms of flexural strength is necessary to ensure that the aged structures can carry the increased traffic load throughout their design life. The steel ribs, which presented in the profiled steel deck, limit the use of shear connectors. This leads to a poor degree of composite action between the concrete slab and steel beam compared to the solid slab situation. As a result, the shear connectors that connects the slab and beam will be subjected to higher shear stress which may also require strengthening to increase the load carrying capacity of an existing composite structure. While most of the available studies focus on the strengthening of longitudinal shear and flexural strength separately, the present work investigates the effect of both flexural and longitudinal shear strengthening of steel-concrete composite beam with composite slab in terms of failure modes, ultimate load carrying capacity, ductility, end-slip, strain profile and interface differential strain. The flexural strengthening was conducted using carbon fibre reinforced polymer (CFRP) or steel plate on the soffit of the steel I-beam, while longitudinal shear capacity was enhanced using post-installed high strength bolts. Moreover, a combination of both the longitudinal shear and flexural strengthening techniques was also implemented (hybrid strengthening). It is concluded that hybrid strengthening improved the ultimate load carrying capacity and reduce slip and interface differential strain that lead to improved composite action. However, hybrid strengthening resulted in brittle failure mode that decreased ductility of the beam.

Key Words
strengthening; steel-concrete composite; FRP; welded plate; longitudinal shear; profiled steel sheeting; steel deck

Address
Mahbube Subhani, Muhammad Ikramul Kabir and Riyadh Al-Ameri: School of Engineering, Deakin University, 75 Pigdons Road, Waurn Ponds, VIC 3216, Australia


Abstract
Moment resisting stub columns (MRSCs) have increasingly adopted in special moment-resisting frame (SMF) systems in steel building structures, especially in Asian countries. The MRSCs typically provide a lower deformation capacity compared to shear-panel stub columns, a limited post-yield stiffness, and severe strength degradation as adopting slender webs. A new MRSC design with cored configuration, consisting of a core-segment and two side-segments using different steel grades, has been proposed in the study to improve the demerits mentioned above. Several full-scale components of the cored MRSC were experimentally investigated focusing on the hysteretic performance of plastic hinges at the ends. The effects of the depths of the core-segment and the adopted reduced column section details on the hysteretic behavior of the components were examined. The measured hysteretic responses verified that the cored MRSC enabled to provide early yielding, great ductility and energy dissipation, enhanced post-yield stiffness and limited strength degradation due to local buckling of flanges. A parametric study upon the dimensions of the cored MRSC was then conducted using numerical discrete model validated by the measured responses. Finally, a set of model equations were established based on the results of the parametric analysis to accurately estimate strength backbone curves of the cored MRSCs under increasing-amplitude cyclic loadings.

Key Words
stub columns; moment resisting frames; post-yield stiffness; reduced column sections

Address
Po-Chien Hsiao: Department of Civil and Construction Engineering, National Taiwan University of Science and Technology, 43 Keelung Rd., Sec.4, Taipei City 106, Taiwan
Kun-Sian Lin and Wei-Chieh Liao: Department of Civil Engineering, National Chung Hsing University, 145 Xingda Rd., South Dist., Taichung City 402, Taiwan
Limeng Zhu and Chunwei Zhang: School of Civil Engineering, Qingdao University of Technology, 11 Fushun Rd., Shibei Dist., Qingdao, 266033, P.R. China


Abstract
The tube outward local buckling of Concrete-Filled Steel Tube (CFST) beam under high compression stress is still considered a critical problem, especially for steel tubes with a slender section compared to semi-compact and compact sections. In this study, the flexural performance of stiffened slender cold-formed square tube beams filled with normal concrete was investigated. Fourteen (14) simply supported CFST specimens were tested under static bending loads, stiffened with different shapes and numbers of steel stiffeners that were provided at the inner sides of the tubes. Additional finite element (FE) CFST models were developed to further investigate the influence of using internal stiffeners with varied thickness. The results of tests and FE analyses indicated that the onset of local buckling, that occurs at the top half of the stiffened CFST beam cross-section at mid-span was substantially restricted to a smaller region. Generally, it was also observed that, due to increased steel area provided by the stiffeners, the bending capacity, flexural stiffness and energy absorption index of the stiffened beams were significantly improved. The average bending capacity and the initial flexural stiffness of the stiffened specimens for the various shapes, single stiffener situations have increased of about 25% and 39%, respectively. These improvements went up to 45% and 60%, for the double stiffeners situations. Moreover, the bending capacity and the flexural stiffness values obtained from the experimental tests and FE analyses validated well with the values computed from equations of the existing standards.

Key Words
slender tube section; CFST beam; internal stiffeners; buckling failure; stiffening; cold-formed tube

Address
Ahmed W. Al Zand, W.H. Wan Badaruzzaman, Mustafa M. Ali and Qahtan A. Hasan: Smart and Sustainable Township Research Centre, Universiti Kebangsaan Malaysia (UKM), Selangor, Malaysia
Marwan S. Al-Shaikhli: Civil Engineering Department, Madenat Alelem University College, Baghdad, Iraq

Abstract
In the present paper, free vibration analysis of angle-ply laminated composite annular and circular plates is performed by numerical methods. First-order shear deformation plate theory is used for kinematic relations. The related governing equations of motion are discretized via differential quadrature and discrete singular convolution methods. Frequency values are obtained for different lamina scheme, thickness-to-radius ratio, and mode numbers. The advantages and accuracy of these two methods are also tested in detail.

Key Words
laminated composites; annular plates; circular plate; discrete singular convolution

Address
Kadir Mercan: kdeniz University, Engineering Faculty, Division of Mechanics, Antalya, Turkey
Farzad Ebrahimi: Imam Khomeini International University, Mechanical Engineering Dept. Qazvin, Iran
Ömer Civalek: China Medical University, Research Center for Interneural Computing, Taichung-Taiwan

Abstract
Different parameters potentially affect the properties of corroded reinforced concrete beams. However, the high number of these parameters and their dependence cause that the effectiveness of the parameters could not be simply identified. In this study, an adaptive neuro-fuzzy inference system (ANFIS) was employed to determine the most influencing parameters on the properties of the corrosion-damaged reinforced concrete beams. 207 ANFIS models were developed to analyze the collected data from 107 reinforced concrete (RC) beams. The impact of 23 input parameters on nine output factors was investigated. The results of the paper showed the order of influence of each input parameter on the outputs and revealed that the input parameters regarding the uncorroded properties of concrete beams are the most influencing factors on the corresponding corroded properties of the beams.

Key Words
Adaptive Neuro-Fuzzy Inference System; system identification; corrosion; reinforced concrete beams

Address
Mahdi Shariati and Nguyen Thoi Trung: Division of Computational Mathematics and Engineering, Institute for Computational Science,
Ton Duc Thang University, Ho Chi Minh City, Vietnam;
Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam
Mohammad Saeed Mafipour: School of Civil Engineering, College of Engineering, University of Tehran,Tehran, Iran
James H. Haido: Department of Civil Engineering, College of Engineering, University of Duhok, Kurdistan Region, Iraq
Salim T. Yousif: Department of Civil Engineering, Al-Qalam University College, Kirkuk, Iraq
Ali Toghroli and Ali Shariati: Institute of Research and Development, Duy Tan University, Da Nang 550000, Viet Nam




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