Al-Zand, Ahmed W.
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Journal : Civil Engineering Journal

Evaluating Axial Strength of Cold-formed C-Section Steel Columns Filled with Green High-performance Concrete Jasim, Al Mashhadani D. A.; Wong, Leong Sing; Al-Zand, Ahmed W.; Kong, Sih Ying
Civil Engineering Journal Vol 10 (2024): Special Issue "Sustainable Infrastructure and Structural Engineering: Innovations in
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-SP2024-010-014

Abstract

Concrete-filled steel tube (CFST) columns that experience outward local buckling under high axial stress remain a significant concern, particularly when thin steel sections are used, as opposed to semi-compact and compact sections. This study investigated the performance of column systems by comparing single- and double-C-section configurations with both hollow and concrete-filled designs. Two types of infill materials were investigated: normal concrete and recycled material concrete, which included 10% waste glass powder as a cement replacement, 8% black high-density polyethylene beads as a sand substitute, and 10% pumice stone as coarse aggregate. To enhance the strength of the proposed CFS column, steel strips and screws were used to connect the flanges of the C-sections. Nine columns were tested experimentally under static axial load. Additionally, finite element analysis software was used to model and evaluate the effects of parameters beyond those investigated in the tests. The results indicated that the load capacity of the double face-to-face section was approximately 3% higher than that of the double back-to-back section. The addition of steel strips, used to connect the lips of the C-section flanges, enhanced the axial strength of the column by approximately 2% compared with the unstrengthened corresponding specimen and delayed buckling in the most vulnerable areas. Furthermore, the recycled infill concrete material had a minimal impact on the axial performance of the analyzed CFS columns compared to the control concrete, with a difference of less than 2.2%. The findings confirm that recycled waste material concrete can achieve performance comparable to that of the conventional concrete. Doi: 10.28991/CEJ-SP2024-010-014 Full Text: PDF
Flexural Performance of a New Composite Double PSSDB Slab System Filled with Recycled Concrete Al-Sudani, Zaid A.; De’nan, Fatimah; Al-Zand, Ahmed W.; Abd Rahman, Noorhazlinda; Liejy, Mohammed C.
Civil Engineering Journal Vol 10, No 12 (2024): December
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2024-010-12-03

Abstract

This study investigated the flexural performance of a composite floor system utilizing a profile steel sheet dry board (PSSDB) that was enhanced by adding an additional layer of profile steel sheet (PSS) and infilled with both normal and recycled concrete materials. This improved system is referred to as the double-profile steel sheet dry board (DPSSDB) system. The new DPSSDB concept was proposed to reduce fabrication costs, overall weight, and the depth of the composite floor system compared to traditional composite beam-slab systems. To assess the impact of the additional PSS layer, ten full-scale specimens of both PSSDB and DPSSDB were subjected to four-point static load tests. Additionally, the study investigated the use of lightweight recycled aggregates such as crumb rubber and expanded polystyrene as partial replacements for the aggregates in the infill concrete. The results demonstrated that the DPSSDB system exhibited a 112–170% increase in bending capacity compared to the PSSDB specimens. Partial replacement of concrete aggregates with lightweight recycled materials up to 50% had only a marginal effect on the bending behavior of both PSSDB and DPSSDB specimens compared to those filled with normal concrete. However, replacing 75% of the aggregate with recycled materials led to a 27% reduction in the flexural bending capacity of the DPSSDB specimens compared to those infilled with normal concrete. Additionally, a new method (theoretical equation) was developed to predict the ultimate moment strength (flexural) of the novel DPSSDB composite slab system, which aligned well with the experimental results, achieving a deviation percentage of 0.81% and a mean value of 0.965a. Doi: 10.28991/CEJ-2024-010-12-03 Full Text: PDF
Flexural Behaviour of Precast Lightweight Concrete Sandwich Slabs With Demountable Bolted Steel Shear Connectors Al-Kerwei, Rana H.; Osman, S. A.; Al-Zand, Ahmed W.; Hanoon, Ammar N.
Civil Engineering Journal Vol 11, No 2 (2025): February
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2025-011-02-06

Abstract

A concrete slab is a fundamental element and contributes the highest weight in structural buildings. In this paper, a new type of sandwich slab consisting of two layers of lightweight concrete and demountable steel connectors is proposed in a new attempt to reduce the weight of the floors within the structure and apply a simpler and faster approach to connecting the layers of sandwich panels. The structural effects of the proposed connectors on Precast Lightweight Concrete Sandwich Slab (PLCSS) are evaluated experimentally and theoretically in terms of strength, stiffness, degree of composite action, and usability for floor construction. The behaviors of six PLCSS specimens subjected to four-point loads were investigated, studying the effects of varied parameters such as different numbers, arrangements, and shapes of demountable steel connectors (I, V, and X connector shapes) fastened with steel bolts, in addition to one solid concrete slab as a reference specimen. The panels' performance in this structural system was evaluated by measuring the degree of composite action using load, displacement, stress, and neutral axis methods. Based on the experimental results, the slab panels exhibited composite panel behavior until the point of failure. Under flexural loads, the panel behaved similarly to that of a solid one-way slab; crack patterns appeared in one direction. The specimens with IC, VC, and XC showed different load capacity values, ranging from 22.74 kN to 50.55 kN; these values depend on the types of shear connectors and their numbers in the sandwich panels. Using V and X connectors enhances the composite action between layers, increasing the shear demand and making the shear failure more likely. It can be concluded that demountable shear connectors can transfer shear between the two concrete wythes, resulting in a composite panel with structural integrity, a lighter weight, and satisfying ACI specifications for floor applications. Doi: 10.28991/CEJ-2025-011-02-06 Full Text: PDF