Elevated temperature resistance of concrete columns with axial loading

Alaskar, Abdulaziz,Alyousef, Rayed,Alabduljabbar, Hisham,Alrshoudi, Fahed,Mohamed, Abdeliazim Mustafa,Jermsittiparsert, Kittisak,Ho, Lanh Si Techno-Press 2020 Advances in concrete construction Vol.9 No.4

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.

Depiction of concrete structures with seismic separation under faraway fault earthquakes

Luo, Liang,Nguyen, Hoang,Alabduljabbar, Hisham,Alaskar, Abdulaziz,Alrshoudi, Fahed,Alyousef, Rayed,Nguyen, Viet-Duc,Dang, Hoang-Minh Techno-Press 2020 Advances in concrete construction Vol.9 No.1

One of the most suitable methods in structural design is seismic separator. Lead-Rubber Bearing (LRB) is one of the most well-known separation systems which can be used in different types of structures. This system mitigates the earthquake acceleration prior to transferring to the structure efficiently. However, the performance of this system in concrete structures with different heights have not been evaluated thoroughly yet. This paper aims to evaluate the performance of LRB separation system in concrete structures with different heights. For this purpose, three, 16, and 23 story concrete structures are equipped by LRB and exposed to a far-field earthquake. Next, a time history analysis is conducted on each of the structures. Finally, the performance of the concrete structures is compared with each other in the term of their response to the earthquakes and the formation of plastic hinges. The results of the paper show that the rate of change in acceleration response and the ratio of drift along the height of 8 and 23 stories concrete structures are more than those of the 16-stories, and the use of LRB reduces the formation of plastic joints.

Effect of molar ratios on strength, microstructure & embodied energy of metakaolin geopolymer

Abadel, Aref A.,Albidah, Abdulrahman S.,Altheeb, Ali H.,Alrshoudi, Fahed A.,Abbas, Husain,Al-Salloum, Yousef A. Techno-Press 2021 Advances in concrete construction Vol.11 No.2

In this study, twenty-five geopolymer (GP) mixes were prepared by varying the alkaline solids to Metakaolin (MK) and sodium silicate to NaOH ratios from 0.1 to 0.5 and 0.2 to 1.0, respectively, thus giving a wide range of molar ratios of silica to alumina, sodium oxide to alumina and water to sodium oxide. The compressive strength of these GP mixes was determined for four curing schemes involving oven curing at 100℃ for 24 h and three ambient curing with the curing ages of 3, 14, and 28 days. The test results revealed that for the manufacture of GP binder for structural applications of strength up to 90 MPa, the molar ratio of silica to alumina should be greater than 2.3, sodium oxide to alumina should be between 0.6 to 1.2, and water to sodium oxide should not exceed 12. The compressive strength of ambient cured GP mortar gets stabilized at 28 days of ambient curing. Experimental findings were also corroborated by GP microstructure analysis. The embodied energy of MK-based GP mortars, especially of high strength, is significantly less than the cement mortar of equivalent strength.

Computational estimation of the earthquake response for fibre reinforced concrete rectangular columns

Chanjuan Liu,Xinling Wu,Karzan Wakil,Kittisak Jermsittiparsert,Lanh Si Ho,Hisham Alabduljabbar,Abdulaziz Alaskar,Fahed Alrshoudi,Rayed Alyousef,Abdeliazim Mustafa Mohamed 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.5

Due to the impressive flexural performance, enhanced compressive strength and more constrained crack propagation, Fibre-reinforced concrete (FRC) have been widely employed in the construction application. Majority of experimental studies have focused on the seismic behavior of FRC columns. Based on the valid experimental data obtained from the previous studies, the current study has evaluated the seismic response and compressive strength of FRC rectangular columns while following hybrid metaheuristic techniques. Due to the non-linearity of seismic data, Adaptive neuro-fuzzy inference system (ANFIS) has been incorporated with metaheuristic algorithms. 317 different datasets from FRC column tests has been applied as one database in order to determine the most influential factor on the ultimate strengths of FRC rectangular columns subjected to the simulated seismic loading. ANFIS has been used with the incorporation of Particle Swarm Optimization (PSO) and Genetic algorithm (GA). For the analysis of the attained results, Extreme learning machine (ELM) as an authentic prediction method has been concurrently used. The variable selection procedure is to choose the most dominant parameters affecting the ultimate strengths of FRC rectangular columns subjected to simulated seismic loading. Accordingly, the results have shown that ANFIS-PSO has successfully predicted the seismic lateral load with R2 = 0.857 and 0.902 for the test and train phase, respectively, nominated as the lateral load prediction estimator. On the other hand, in case of compressive strength prediction, ELM is to predict the compressive strength with R2 = 0.657 and 0.862 for test and train phase, respectively. The results have shown that the seismic lateral force trend is more predictable than the compressive strength of FRC rectangular columns, in which the best results belong to the lateral force prediction. Compressive strength prediction has illustrated a significant deviation above 40 Mpa which could be related to the considerable non-linearity and possible empirical shortcomings. Finally, employing ANFIS-GA and ANFIS-PSO techniques to evaluate the seismic response of FRC are a promising reliable approach to be replaced for high cost and time-consuming experimental tests.

The effect of wollastonite powder with pozzolan micro silica in conventional concrete containing recycled aggregate

Du Dinh-Cong,Mohammad. H. Keykhosravi,Rayed Alyousef,Musab N.A. Salih,Hoang Nguyen,Hisham Alabduljabbar,Abdulaziz Alaskar,Fahed Alrshoudi,Shek Poi-Ngian 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.24 No.4

Construction development and greenhouse gas emissions have globally required a strategic management to take some steps to stain and maintain the environment. Nowadays, recycled aggregates, in particular ceramic waste, have been widely used in concrete structures due to the economic and environmentally friendly solution, requiring the knowledge of recycled concrete. Also, one of the materials used as a substitute for concrete cement is wollastonite mineral to decrease carbon dioxide (CO2) from the cement production process by reducing the concrete consumption in concrete. The purpose of this study is to investigate the effect of wollastonite on the mechanical properties and durability of conventional composite concrete, containing recycled aggregates such as compressive strength, tensile strength (Brazilian test), and durability to acidic environment. On the other hand, in order to determine the strength and durability of the concrete, 5 mixing designs including different wollastonite values and recovered aggregates including constant values have been compared to the water - cement ratio (w/c) constant in all designs. The experimental results have shown that design 5 (containing 40% wollastonite) shows only 6.1% decrease in compressive strength and 4.9% decrease in tensile strength compared to the control plane. Consequently, the use of wollastonite powder to the manufacturing of conventional structural concrete containing recycled ceramic aggregates, in addition to improving some of the properties of concrete are environmentally friendly solutions, providing natural recycling of materials.

Computational analysis of three dimensional steel frame structures through different stiffening members

Abdulaziz Alaskar,Karzan Wakil,Rayed Alyousef,Kittisak Jermsittiparsert,Lanh Si Ho,Hisham Alabduljabbar,Fahed Alrshoudi,Abdeliazim Mustafa Mohamed 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.2

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.

Investigation on the monotonic behavior of the steel rack upright-beam column connection

Yan Cao,Rayed Alyousef,Kittisak Jermsittiparsert,Lanh Si Ho,Abdulaziz Alaskar,Hisham Alabduljabbar,Fahed Alrshoudi,Abdeliazim Mustafa Mohamed 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.1

The cold-formed steel storage racks are extensively employed in various industries applications such as storing products in reliable places and storehouses before distribution to the market. Racking systems lose their stability under lateral loads, such as seismic actions due to the slenderness of elements and low ductility. This justifies a need for more investigation on methods to improve their behavior and increase their capacity to survive medium to severe loads. A standardized connection could be obtained through investigation on the moment resistance, value of original rotational stiffness, ductility, and failure mode of the connection. A total of six monotonic tests were carried out to determine the behavior of the connection of straight 2.0 mm, and 2.6 mm thickness connects to 5 lug end connectors. Then, the obtained results are benched mark as the original data. Furthermore, an extreme learning machine (ELM) technique has been employed to verify and predict both moment and rotation results. Out of 4 connections, increase the ultimate moment resistance of connection by 13% and 18% for 2.0 mm and 2.6 mm upright connection, respectively.

Cold-Formed Steel Lipped Channel Section Columns Undergoing Local-Overall Buckling Interaction

Krishanu Roy,Tina Chui Huon Ting,Hieng Ho Lau,Rehan Masood,Rayed Alyousef,Hisham Alabduljabbar,Abdulaziz Alaskar,Fahed Alrshoudi,James B. P. Lim 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.2

This paper presents an experimental and fi nite element (FE) investigation into the local-overall buckling interaction behaviour of axially loaded cold-formed steel (CFS) channel section columns. Current design guidelines from the American Iron and Steel Institute (AISI) and the Australian and New Zealand Standards (AS/NZS) recommend the use of a non-dimensional strength curve for determining the axial capacity of such CFS channel section columns. This study has reviewed the accuracy of the current AISI (2016), AS/NZS (2018) and Eurocode (EN 1993-1-3) design guidelines for determining the axial capacity of CFS channel sections under local-overall buckling interaction failure. A total of 40 tests were conducted on CFS channel sections covering stub, short, intermediate, and slender columns with varying thicknesses. A nonlinear FE model was then developed and validated against the test results. The validated FE model was used to conduct a parametric study comprising 70 FE models to review the accuracy of the current design guidelines in accordance with AISI (2016), AS/NZS (2018) and Eurocode (EN 1993-1-3). It was found that the AISI (2016) and AS/NZS (2018) are conservative by 10 to 15% on average when determining the axial capacity of pin-ended CFS channel section columns undergoing local-overall buckling interaction. Eurocode (EN 1993-1-3) design rules were found to lead to considerably more conservative predictions of column axial load capacity for CFS channels.This paper has therefore proposed modifi cations to the current design rules of AISI (2016) and AS/NZS (2018). The accuracy of proposed design rules was verifi ed using the FE analysis and test results of CFS channel section columns undergoing local-overall buckling interaction.

Optimizing reinforced concrete beams under different load cases and material mechanical properties using genetic algorithms

Enqiang Zhu,Rabi Muyad Najem,Du Dinh-Cong,Zehui Shao,Karzan Wakil,Lanh Si Ho,Rayed Alyousef,Hisham Alabduljabbar,Abdulaziz Alaskar,Fahed Alrshoudi,Abdeliazim Mustafa Mohamed 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.4

Genetic Algorithm (GA) is a meta-heuristic algorithm which is capable of providing robust solutions for optimal design of structural components, particularly those one needs considering many design requirements. Hence, it has been successfully used by engineers in the typology optimization of structural members. As a novel approach, this study employs GA in order for conducting a case study with high constraints on the optimum mechanical properties of reinforced concrete (RC) beams under different load combinations. Accordingly, unified optimum sections through a computer program are adopted to solve the continuous beams problem. Genetic Algorithms proved in finding the optimum resolution smoothly and flawlessly particularly in case of handling many complicated constraints like a continuous beam subjected to different loads as moments shear - torsion regarding the curbs of design codes.