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CONTENTS
Volume 9, Number 4, April 2020
 

Abstract
In the present study, by employing fragility analysis, the seismic vulnerability of a concrete girder bridge, one of the most common existing structural bridge systems, has been performed. To this end, drift demand model as a fundamental ingredient of any probabilistic decision-making analyses is initially developed in terms of the two most common intensity measures, i.e., PGA and Sa (T1). Developing a probabilistic demand model requires a reliable database that is established in this paper by performing incremental dynamic analysis (IDA) under a set of 20 ground motion records. Next, by employing Bayesian statistical inference drift demand models are developed based on pre-collapse data obtained from IDA. Then, the accuracy and reasonability of the developed models are investigated by plotting diagnosis graphs. This graphical analysis demonstrates probabilistic demand model developed in terms of PGA is more reliable. Afterward, fragility curves according to PGA based-demand model are developed.

Key Words
Bayesian Interface; Finite Element Modeling (FEM); Fragility Function Methodology; Probabilistic Seismic Demand Analysis (PSDA)

Address
M. Bayat: Department of Civil and Environmental Engineering, University of South Carolina, Columbia, SC, USA
M. Kia: Department of Civil Engineering, University of Science and Technology of Mazandaran, Behshahr, Iran
V. Soltangharaei: Department of Civil and Environmental Engineering, University of South Carolina, Columbia, SC, USA
H.R. Ahmadi: Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh P.O. Box 55136-553, Iran
P. Ziehl: Department of Civil and Environmental Engineering, University of South Carolina, Columbia, SC, USA

Abstract
Cement is the most significant component in concrete. Large scale manufacturing of cement consumes more energy and release harmful products (Carbon dioxide) into the atmosphere that adversely affect the environment and depletes the natural resources. A lot of research is going on in globally concentrating on the recycling and reuse of waste materials from many industries. A major share of research is focused on finding cementitious materials alternatives to ordinary Portland cement. Many industrial waste by-products such as quartz powder, metakaolin, ground granulated blast furnace slag, silica fume, and fly ash etc. are under investigations for replacement of cement in concrete to minimize greenhouse gases and improve the sustainable construction. In current research, the effects of a new generation, ultra-fine material i.e., alccofine which is obtained from ground granulated blast furnace slag are studied as partial replacement by 25% and with varying amounts of sulfonated naphthalene formaldehyde (i.e., 0.3%, 0.35% and 0.40%) on mechanical, water absorption, thermal and microstructural properties of concrete. The results showed moderate improvement in all concrete properties. Addition of SNF with combination of alccofine showed a significant enhancement in fresh, hardened properties and water absorption test as well as thermal and microstructural properties of concrete.

Key Words
alccofine; mechanical properties; thermogravimetric analysis; microanalysis properties

Address
Panga Narasimha Reddy: Department of Civil Engineering, National Institute of Technology, Srinagar, J&K, India
Bharat Bhushan Jindal: School of Civil Engineering, Shri Mata Vaishno Devi University, J&K, India
Bode Venkata Kavyateja: JNTUA College of Engineering, Kalikiri, Andhra Pradesh, India
A. Narender Reddy: Department of Structural Engineering, VIT, Vellore, Tamil Nadu, 632014, India

Abstract
The influence of temperature on the material of concrete filled columns (CFCs) under axial loading has been quantitatively studied in this research. CFCs have many various advantages and disadvantages. One of the important inefficiency of classic CFCs design is the practical lack of hooped compression under the operational loads because of the fewer variables of Poisson\'s rate of concrete compared to steel. This is the reason why the holder tends to break away from the concrete core in elastic stage. It is also suggested to produce concrete filled steel tube columns with an initial compressed concrete core to surpass their design. Elevated temperatures have essentially reduced the strengths of steel tubes and the final capacity of CFCs exposed to fire. Thus, the computation of bearing capacity of concrete filled steel tube columns is studied here. Sometimes, the structures of concrete could be exposed to the high temperatures during altered times, accordingly, outcomes have shown a decrement in compressive-strength, then an increase with the reduction of this content. In addition, the moisture content at the minimal strength is declined with temperature rising. According to Finite Element (FE), the column performance assessment is carried out according to the axial load carrying capacities and the improvement of ductility and strength because of limitations. Self-stress could significantly develop the ultimate stiffness and capacity of concrete columns. In addition, the design equations for the ultimate capacity of concrete columns have been offered and the predictions satisfactorily agree with the numerical results. The proposed based model (FE model of PEC column) 65% aligns with the concrete exposed to high temperature. Therefore, computed solutions have represented a better perception of structural and thermal responses of CFC in fire.

Key Words
elevated temperatures; finite element technique; concrete-filled columns; mathematical model

Address
Abdulaziz Alaskar: Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11362, Saudi Arabia
Rayed Alyousef: Department of Civil Engineering, College of Engineering, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
Hisham Alabduljabbar: Department of Civil Engineering, College of Engineering, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
Fahed Alrshoudi: Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11362, Saudi Arabia
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
Concrete surfaces, industrial floors, sidewalks, roads and parking lots are typically subjected to abrasions. Many studies indicated that the abrasion resistance is directly related to the ultimate strength of the cured concrete. Chemical reactions, freeze-thaw cycles, and damages under abrasion are among many factors negatively affecting the concrete strength and durability. One of the major solutions to address the abrasive resistance of the concrete is to use fibers. Fibers are used in the concrete mix to improve the mechanical properties, strength and limit the crack propagations. In this study, implementation of the steel fibers in concrete to enhance the abrasive resistance of the concrete is investigated in details. The abrasive resistance of the concrete with and without steel fibers is studied with the sandblasting technique. For this purpose, different concrete samples are made with various hooked steel fiber ratios and investigated with the sandblasting method for two different strike angles. In total, 144 ASTM verified cube samples are investigated and it is shown that those samples with the highest steel fiber ratios have the highest abrasive resistance. In addition, the experiments determine that there is a meaningful correlation between the steel fiber percentage in the mix, strike angle and curing time which could be considered for improving structural behavior of the fiber-reinforced concrete.

Key Words
abrasion resistance; fiber-reinforced concrete; sandblast; compressive strength; steel fiber

Address
Iman Mansouri: Department of Civil Engineering, Birjand University of Technology, 97175-569 Birjand, Iran; Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
Farzaneh Sadat Shahheidari: Department of Civil Engineering, Higher Education Complex of Hormozan, Birjand, Iran
Seyyed Mohammad Ali Hashemi: Faculty of Civil Engineering, Sadjad University of Technology, Mashhad, Iran
Alireza Farzampour: Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, United States

Abstract
In the present study, the effect of basalt, glass, and hybrid glass-basalt fibers on mechanical properties and fracture behavior of self-compacting concrete (SCC) mixes have been assessed at room and elevated temperatures. To do so, twelve mix compositions have been prepared such that the proper workability, flowability, and passing ability have been achieved. Besides, to make comparison possible, water to binder ratio and the amount of solid contents were kept constant. Four fiber dosages of 0.5, 1, 1.5, and 2% (by concrete volume) were considered for monotype fiber reinforced mixes, while the total amount of fiber were kept 1% for hybrid fiber reinforced mixes. Three different portions of glass and basalt fiber were considered for hybridization of fibers to show the best cocktail for hybrid basalt-glass fiber. Test results indicated that the fracture energy of mix is highly dependent on both fiber dosage and temperature. Moreover, the hybrid fiber reinforced mixes showed the highest fracture energies in comparison with monotype fiber reinforced specimens with 1% fiber volume fraction. In general, hybridization has played a leading role in the improvement of mechanical properties and fracture behavior of mixes, while compared to monotype fiber reinforced specimens, hybridization has led to lower amounts of compressive strength.

Key Words
fracture energy; fiber reinforced SCC; temperature; hybridization of fibers

Address
Moosa Mazloom, Hemin Karimpanah and Mohammad Karamloo: Department of Civil Engineering, Shahid Rajaee Teacher Training University, Lavizan, Tehran, Iran

Abstract
This study has been carried out in two-phases to develop Fiber Reinforced Self-Compacting Concrete (FRSCC) performance. In the first phase, the composition of the quaternary composite binder compromised CEM I 42.5N (58-70%), Rice Husk Ash (25-37%), quartz sand (2.5-7.5%) and limestone crushing waste (2.5-7.5%) were optimized. And in the second phase, the effect of two fiber types (steel brass-plated and basalt) was investigated on the SCC optimized with the optimum CB as disperse reinforcement at 6 different ratios of 1, 1.2, 1.4, 1.6, 1.8, and 2.0% by weight of mix for each type. In this study, the theoretical principles of the synthesis of self-compacting dispersion-reinforced concrete have been developed which consists of optimizing structure-formation processes through the use of a mineral modifier, together with ground crushed cement in a vario-planetary mill to a specific surface area of 550 m2 / kg. The amorphous silica in the modifier composition intensifies the binding of calcium hydroxide formed during the hydration of C3S, helps reduce the basicity of the cement-composite, while reducing the growth of portlandite crystals. Limestone particles contribute to the formation of calcium hydrocarbonate and, together with fine ground quartz sand; act as microfiller, clogging the pores of the cement. Furthermore, the results revealed that the effect of fiber addition improves the mechanical properties of FRSCC. It was found that the steel fiber performed better than basalt fiber on tensile strength and modulus of elasticity; however, both fibers have the same performance on the first crack strength and sample destruction of FRSCC. It also illustrates that there will be an optimum percentage of fiber addition.

Key Words
FRSCC; quaternary composite binders; fibers; mechanical properties; first crack; destruction

Address
Roman Fediuk: School of Engineering, Far Eastern Federal University, Vladivostok, Russian Federation
Mohammad A. Mosaberpanah: Department of Civil Engineering, Cyprus International University (CIU), Nicosia, North Cyprus, Turkey
Valery Lesovik: Building Materials Science, Products and Structures, Belgorod State Technological University, Belgorod, Russian Federation

Abstract
The present article deals with post-buckling of geometrically imperfect concrete plates reinforced by graphene oxide powder (GOP) based on general higher order plate model. GOP distributions are considered as uniform and linear models. Utilizing a shear deformable plate model having five field components, it is feasible to verify transverse shear impacts with no inclusion of correction factor. The nonlinear governing equations have been solved via an analytical trend for deriving postbuckling load-deflection relations of the GOP-reinforced plate. Derived findings demonstrate the significance of GOP distributions, geometric imperfectness, foundation factors, material compositions and geometrical factors on post-buckling properties of reinforced concrete plates.

Key Words
post-buckling; general plate theory; concrete plate; graphene oxide powder; nonlinear stability

Address
Seyed Sajad Mirjavadi: Department of Mechanical and Industrial Engineering, Qatar University, P.O. Box 2713, Doha, Qatar
Masoud Forsat: Department of Mechanical and Industrial Engineering, Qatar University, P.O. Box 2713, Doha, Qatar
Yahya Zakariya Yahya: Auckland Bioengineering Institute, the University of Auckland, Auckland, New Zealand
Mohammad Reza Barati: Fidar project Qaem Company, Darvazeh Dolat, Tehran, Iran
Anirudh Narasimamurthy Jayasimha: Bonn-Rhein-Sieg University of Applied Science, Sankt Augustin, Germany
Imran Khan: Department of Electrical Engineering, University of Engineering & Technology, Peshawar 814, Pakistan

Abstract
Due to the influence of nonlinearity and time-variation, it is difficult to establish an accurate model of concrete frame structures that adopt active controllers. Fuzzy theory is a relatively appropriate method but susceptible to human subjective experience to decrease the performance. To guarantee the stability of multi-time delays complex system with multi-interconnections, a delay-dependent criterion of evolved design is proposed in this paper. Based on this criterion, the sector nonlinearity which converts the nonlinear model to multiple rule base of the linear model and a new sufficient condition to guarantee the asymptotic stability via Lyapunov function is implemented in terms of linear matrix inequalities (LMI). A numerical simulation for a three-layer reinforced concrete frame structure subjected to earthquakes is demonstrated that the proposed criterion is feasible for practical applications.

Key Words
RC frame structure; fuzzy systems; multiple time delays; delay-dependent criterion

Address
Tim Chen: AI LAB, Faculty of Information Technology, Ton Duc Thang University, Ho Chi Minh City, Vietnam
Dar Kau: Department Electrical & Electronic Engineering, University of Bath, Bath, BA2 7AY, U.K.
Y. Tai: Mechanical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
C.Y.J. Chen: Department Electrical & Electronic Engineering, University of Bath, Bath, BA2 7AY, U.K; Department of Artificial Intelligence, University of Maryland, Maryland 20742, USA

Abstract
For steel-concrete girders made composite using shear studs, initial damage on studs induced by weld defect, unexpected overloading, fatigue and others might degrade the service performance and even threaten the structural safety. This paper conducted a numerical study to investigate the static behavior of damaged stud shear connectors that were embedded in ultra high performance concrete (UHPC). Parameters included damage degree and damage location. The material nonlinear behavior was characterized by multi-linear stress-strain relationship and damage plasticity model. The results indicated that the shear strength was not sensitive to the damage degree when the damage occurred at 2/3d (d is the stud diameter) from the stud root. An increased stud area would be engaged in resisting shear force as the distance of damage location from stud root increased and the failure section becomes inclined, resulting in a less reduction in the shear strength and shear stiffness. The reduction factor was proposed to consider the degradation of the shear strength of the damaged stud. The reduction factor can be calculated using two approaches: a linear relationship and a square relationship with the damage degree corresponding to the shear strength dominated by the section area and the nominal diameter of the damaged stud. It was found that the proposed method is preferred to predict the shear strength of a stud with initial damage.

Key Words
composite bridges; stud shear connector; ultra high performance concrete (UHPC); initial damage; shear strength; finite element analysis

Address
Jianan Qi, Yiqun Tang, Zhao Cheng, Rui Xu and Jingquan Wang: Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, School of Civil Engineering, Southeast University, Nanjing, China

Abstract
Open ground story (OGS) reinforced concrete (RC) buildings are vulnerable to the complete collapse or severe damages under seismic actions. This study investigates the effectiveness of four different strengthening techniques representing the local and global modifications to improve the seismic performance of a non-ductile RC OGS frame. Steel caging and concrete jacketing methods of column strengthening are considered as the local modification techniques, whereas steel bracing and RC shear wall systems are selected as the global strengthening techniques in this study. Performance-based plastic design (PBPD) approach relying on energy-balance concept has been adopted to determine the required design force demand on the strengthening elements. Nonlinear static and dynamic analyses are carried out on the numerical models of study frames to assess the effectiveness of selected strengthening techniques in improving the seismic performance of OGS frame.. Strengthening techniques based on steel braces and RC shear wall significantly reduced the peak interstory drift response of the OGS frame. However, the peak floor acceleration of these strengthened frames is amplified by more than 2.5 times as compared to that of unstrengthened frame. Steel caging technique of column strengthening resulted in a reasonable reduction in the peak interstory drift response without substantial amplification in peak floor acceleration of the OSG frame.

Key Words
performance-based design; reinforced concrete frame; seismic retrofitting; strength; soft-story mechanism

Address
Prajwol Karki: Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi-110016, India
Romanbabu M. Oinam: Department of Civil & Environmental Engineering, Indian Institute of Technology Tirupati, Tirupati- 517506, India
Dipti Ranjan Sahoo: Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi-110016, India


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