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CONTENTS
Volume 10, Number 4, October 2020
 

Abstract
The practice of splicing reinforcing bars in reinforced concrete structures to manage insufficient bar length is a common approach, which is mainly due to transportation limitations on bar length. The splicing of reinforcing bars side by side offers a simple and economical solution to the problem of continuity. This paper examines the influence of different structural parameters such as concrete cover, lap splice length, shear links confinement and concrete strength on the lap splices based on an extensive experimental database of laps and anchorage. The current study shows that increasing the lap splices beyond 50o has no additional benefit for increasing its strength. The results also show that relative to the measured stress, specimens with larger concrete side covers shows higher splice stress compared to the samples with smaller concrete covers.

Key Words
Lap splices; concrete; laps; splicing; cover; reinforcing bars

Address
Yakubu M. Karkarna, Ali Bahadori-Jahromi: School of Computing and Engineering, University of West London, London, W5 5RF, UK
Hamid Zolghadr Jahromi: University of Westminster instead of University of West London, 35 Marylebone Road, London, NW1 5LS, UK
Emily Bonner, Charles Goodchild: The Concrete Centre, London, SW1V 1HU, UK

Abstract
A reliability analysis of the axial compressive load bearing capacity of postfire reinforced concrete (RC) columns strengthened with carbon fiber reinforced polymer (CFRP) sheets was presented. A 3D finite element (FE) model was built for heat transfer analysis using software ABAQUS. Based on the temperature distribution obtained from the FE analysis, the residual axial compressive load bearing capacity of RC columns was worked out using the section method. Formulas for calculating the residual axial compressive load bearing capacity of the columns after fire exposure and the axial compressive load bearing capacity of postfire columns retrofitted with CFRP sheets were developed. Then the Monte Carlo method was used to analyze the reliability of the axial compressive load bearing capacity of the RC columns retrofitted with CFRP sheets using a code developed in MATLAB. The effects of fire exposure time, load ratio, number of CFRP layers, concrete cover thickness, and longitudinal reinforcement ratio on the reliability of the axial compressive load bearing capacity of the columns after fire were investigated. The results show that within 60 minutes of fire exposure time, the reliability index of the RC columns after retrofitting with two layers of CFRPs can meet the requirements of Chinese code GB 50068 (GB 2001) for safety level II. This method is effective and accurate for the reliability analysis of the axial load bearing capacity of postfire reinforced concrete columns retrofitted with CFRP.

Key Words
CFRP; axial compressive capacity; postfire; reliability; Monte Carlo method

Address
Bin Cai: School of Civil Engineering, Jilin Jianzhu University, Changchun, China; School of Mathematics, Computer Science and Engineering, City, University of London, London, UK
Liyan Hao: School of Civil Engineering, Jilin Jianzhu University, Changchun, China
Feng Fu: School of Mathematics, Computer Science and Engineering, City, University of London, London, UK

Abstract
The following paper concentrates on the objective of studying the influences of extent of duration and temperature on the Pozzolanic properties as well as reactivity of locally existing natural clay of Nai Gaj, district Dadu, Sindh Pakistan. The activation of the clay only occurs through heating when temperature in a furnace chamber reaches 600, 700 and 800oC for 1, 2 and 3 hours and at 900 and 1000oC for 1 and 2 hours. Furthermore, the strength activity index (SAI) of advanced pozzolanic material happens to be identified through 20% cement replacement for different samples of calcined clay as per ASTM C-618. The compressive strength test of samples had been operated for 7 and 28-days curing afterwards. The maximum compressive strength had been seen in mix E in which cement was replaced with clay calcined at 700oC for 1 hour that is 27.05 MPa that is 24.31% more than that of control mix. The results gathered from the SAI verdicts the optimal activation temperature is 700oC within a one-hour time period. The SAI at a temperature of 700oC with a one-hour duration at 28 days is 124.31% which happens to satisfy the requirements of the new Pozzolanic material, in order to be applied in mortar/concrete (i.e., 75%). The Energy- dispersive spectrometry (EDS) along with the X-ray diffraction (XRD) have been carried out in means of verifying whether there is silica content or amorphous silica present in metakaolin that has been developed. The findings gathered from the SAI were validated, as the analysis of XRD verified that there is in fact Pozzolanic activity of developed metakaolin. Additionally, based on observation, the activated metakaolin holds a significant influence on the increase in mortar's compressive strength.

Key Words
natural clay; Pozzolanic; Metakaolin; partial replacement; mortar; concrete

Address
Abdulaziz Alaskar: Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11362, Saudi Arabia
S.N.R. Shah: Mehran University of Engineering & Technology, SZAB Campus, Pakistan
Manthar Ali Keerio: Quaid e Awam University College of Engineering Science & Technology, Pakistan
Javed Ali Phulpoto: Mehran University of Engineering & Technology, SZAB Campus, Pakistan
Shahrizan Baharom: Department of Civil Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia
Hamid Assilzadeh: Institute of Research and Development, Duy Tan University, Da Nang 550000, Viet Nam
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
Abdeliazim Mustafa Mohamed: Department of Civil Engineering, College of Engineering, Prince Sattam bin Abdulaziz University, Al-kharj 11942, Saudi Arabia

Abstract
Performance of Sustainable materials continues through using of recycled waste construction materials to minimize the utilization of the natural resources. The cement industry is a major source of CO2 in the atmosphere which is the main cause of global warming. Replacement of OPC with other sustainable cementitious materials has been the most interesting area of researches. This investigation focuses on the properties of alkali-activated mortar with the different replacement ratios of ceramic tile powder (CTP) by fine soil powder (FSP) (0 to 100)% and different molarities of sodium hydroxide concentrations. The experimental program was conducted by examining the compressive strength, water absorption, and water sorptivity. The results showed that the compressive strength of the specimens at age of (28, 56, and 90 days) increases with an increase in the amount of fine soil powder content and decreases at the age of 120 days. Also, minimum water absorption at the age of 90 days was found in the mixes containing 100% fine soil powder. However, fine soil powder replacement had a negative effect on the sorptivity and water absorption values at the age of 120 days. On the other hand, the 12M sodium hydroxide concentration was considered the optimum concentration compared to other concentrations.

Key Words
sustainable alkali-activated mortar; recycled ceramic tile powder; fine soil; mechanical; sorptivity properties

Address
Arass Omer Mawlod: Department of Civil Engineering, University of Raparin, Kurdistan region, Iraq

Abstract
The impacts of reinforcing concrete matrix with steel fibers, polypropylene fibers and recycled plastic fibers using different volume fractions of 0.15%, 0.5%, 1.5% and 2.5% on the compressive and tensile characteristics are experimentally investigated in the current research. Also, flexural behavior of plain concrete (PC) beams, shear performance of reinforced concrete (RC) beams and compressive characteristics of both PC and RC columns reinforced with recycled plastic fibers were studied. The experimental results showed that the steel fibers improved the splitting tensile strength of concrete higher than both the polypropylene fibers and recycled plastic fibers. The end-hooked steel fibers had a positive effect on the compressive strength of concrete while, the polypropylene fibers, the recycled plastic fibers and the rounded steel fibers had a negative impact. Compressive strength of end-hooked steel fiber specimen with volume fraction of 2.5% exhibited the highest value among all tested samples of 32.48 MPa, 21.83% higher than the control specimen. The ultimate load, stiffness, ductility and failure patterns of PC and RC beams in addition to PC and RC columns strengthened with recycled plastic fibers enhanced remarkably compared to non-strengthened elements. The maximum ultimate load and stiffness of RC column reinforced with recycled plastic fibers with 1.5% volume fraction improved by 21 and 15%, respectively compared to non-reinforced RC column.

Key Words
mechanical properties; steel fiber; polypropylene fiber; recycled plastic fiber; beams; columns; deflection; deformation; elasticity modulus; crack pattern; toughness

Address
Sabry Fayed and Walid Mansour: Department of Civil Engineering, Faculty of Engineering, Kafrelsheikh University, Kafrelsheikh, Egypt

Abstract
In the architectural design process, the selection and configuration of the structural system significantly affect the earthquake behaviours of the reinforced concrete buildings. The main purpose of this study, the effects on the earthquake performances and the rough construction cost of the buildings of the slab type in reinforced concrete buildings are to examine comparatively for different local soil classes. The results obtained from this study have been determined that the building model having slabs with beams is safer compared to other types of slabs, especially when considering the vertical bearing structural elements (columns). It also shows that other types of slab, except for slab with beams, reduce the earthquake performances of reinforced concrete buildings, increase the displacement values, 1st natural vibration period values and the cost of rough construction. This matter reveals that slab type is quite important and the preference of beamed slabs in reinforced concrete buildings to be constructed in earthquake zones would be more appropriate in terms of safety and cost.

Key Words
slab type; earthquake performance; rough construction cost; Sta4-Cad

Address
Senol Gursoy and Omer Uludag: Department of Civil Engineering, Karabük University, 78050 Karabük, Turkey

Abstract
In this paper, vibration characteristics of double-walled carbon nanotubes (CNTs) is studied based upon nonlocal elastic shell theory. The significance of small scale is being perceived by developing nonlocal Love shell model. The wave propagation approach has been utilized to frame the governing equations as eigen value system. The influence of nonlocal parameter subjected to diverse end supports has been overtly analyzed. An appropriate selection of material properties and nonlocal parameter has been considered. The influence of changing mechanical parameter Poisson's ratio has been investigated in detail. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.

Key Words
vibration; nonlocal parameter; Poisson

Address
Sehar Asghar: Department of Mathematics, Govt. College University Faisalabad, 38040, Faisalabad, Pakistan
Mohamed Amine Khadimallah: Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 11942, Saudi Arabia; Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia
Muhammad N. Naeem: Department of Mathematics, Govt. College University Faisalabad, 38040, Faisalabad, Pakistan
Madiha Ghamkhar: Mathematics and Statistics Department, University of Agriculture, Faislabad, Pakistan
Khaled Mohamed Khedher: Department of Civil Engineering, College of Engineering, King Khalid University, Abha 61421, Saudi Arabia; Department of Civil Engineering, High Institute of Technological Studies, Mrezgua University Campus, Nabeul 8000, Tunisia
Muzamal Hussain: Department of Mathematics, Govt. College University Faisalabad, 38040, Faisalabad, Pakistan
Souhail Mohamed Bouzgarrou: Civil Engineering Department, Faculty of Engineering, Jazan University, Kingdom of Saudi Arabia
Zainab Ali: Department of Mathematics, Govt. College University Faisalabad, 38040, Faisalabad, Pakistan
Zafar Iqbal: Department of Mathematics, University of Sargodha, Sargodha, Punjab, Pakistan; Department of Mathematics, University of Mianwali, Punjab, Pakistan
S.R. Mahmoud: GRC Department, Faculty of Applied studies, King Abdulaziz University, Jeddah, Saudi Arabia
Ali Algarni: Statistics Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
Muhammad Taj: Department of Mathematics, University of Azad Jammu and Kashmir, Muzaffarabad, 1300, Azad Kashmir, Pakistan
Abdelouahed Tounsi: Materials and Hydrology Laboratory University of Sidi Bel Abbes, Algeria Faculty of Technology Civil Engineering Department, Algeria; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
The impulse of this paper is to examine the influence of unsteady flow comprising of Eyring-Powell nanofluid over a stretched surface. This work aims to explore efficient transfer of heat in Eyring-Powell nanofluid with bio-convection. Nanofluids possess significant features that have aroused various investigators because of their utilization in industrial and nanotechnology. The influence of including motile microorganism is to stabilize the nanoparticle suspensions develop by the mixed influence of magnetic field and buoyancy force. This research paper reveals the detailed information about the linearly compressed Magnetohydrodynamics boundary layer flux of two dimensional Eyring-Powell nanofluid through disposed surface area due to the existence of microorganism with inclusion the influence of non- linear thermal radiation, energy activation and bio-convection. The liquid is likely to allow conduction and thickness of the liquid is supposed to show variation exponentially. By using appropriate similarity type transforms, the nonlinear PDE's are converted into dimensionless ODE's. The results of ODE's are finally concluded by employing (HAM) Homotopy Analysis approach. The influence of relevant parameters on concentration, temperature, velocity and motile microorganism density are studied by the use of graphs and tables. We acquire skin friction, local Nusselt and motil microorganism number for various parameters.

Key Words
Eyring-Powell nanofluid; variable viscosity; thermal radiation; activation energy; motile micro-organism; Homotopy analysis

Address
Humaira Sharif: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
Muhammad N. Naeem: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
Mohamed A. Khadimallah: Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 11942, Saudi Arabia; Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia
Hamdi Ayed: Department of Civil Engineering, College of Engineering, King Khalid University, Abha, Kingdom of Saudi Arabia; Higher Institute of Transport and Logistics of Sousse, University Sousse, Tunisia
Souhail Mohamed Bouzgarrou: Civil Engineering Department, Faculty of Engineering, Jazan University, Kingdom of Saudi Arabia
Abdullah F. Al Naim: Department of Physics, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa 31982, Saudi Arabia
Sajjad Hussain: Department of mathematics, Government Post graduate College, Layyah, Pakistan
Muzamal Hussain: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
Zafar Iqbal: Department of Mathematics, University of Sargodha, Sargodha, Punjab, Pakistan; Department of Mathematics, University of Mianwali, Punjab, Pakistan
Abdelouahed Tounsi: Materials and Hydrology Laboratory University of Sidi Bel Abbes, Algeria Faculty of Technology Civil Engineering Department, Algeria; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia


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