Research Article
Reliability-Based Evaluation of Hollow Reinforced Concrete Beams with Variable Void Positions
Isah Aminu,
John Wasiu,
Ibrahim Abdulrazaq Olayinka*
,
Haruna Daud Gussau
Issue:
Volume 10, Issue 2, December 2026
Pages:
47-53
Received:
21 April 2026
Accepted:
11 June 2026
Published:
3 July 2026
Abstract: This study presents a reliability-based evaluation of the flexural behavior of reinforced concrete (RC) beams containing voids formed using polyvinyl chloride (PVC) pipes positioned at varying distances along the beam length. Six beam specimens measuring 500 mm × 100 mm × 100 mm were cast and tested, with voids located between 0 mm and 200 mm from the beam ends. The experimental program followed ASTM and BS 8100 standards to determine the concrete’s physical and mechanical properties, including slump, water absorption, and flexural strength. Results showed that the beam performance was highly dependent on void positioning. Beams with voids placed 100 mm from the supports recorded the highest flexural strength of 3.10 N/mm2 at 28 days, surpassing the control beam (2.90 N/mm2). Reliability analysis, performed using the First Order Reliability Method (FORM) as recommended by the Joint Committee on Structural Safety, yielded an average reliability index (β) of 3.32, representing a 50% improvement in safety prediction accuracy compared to deterministic design. The findings confirm that strategically positioned voids can improve structural efficiency and material economy without compromising safety. Consequently, the study concludes that reliability-based design provides a robust framework for sustainable and optimized reinforced concrete beam construction.
Abstract: This study presents a reliability-based evaluation of the flexural behavior of reinforced concrete (RC) beams containing voids formed using polyvinyl chloride (PVC) pipes positioned at varying distances along the beam length. Six beam specimens measuring 500 mm × 100 mm × 100 mm were cast and tested, with voids located between 0 mm and 200 mm from ...
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Research Article
An Experimental Study on the Compressive Strength of Recycled Stone Aggregate Concrete
Issue:
Volume 10, Issue 2, December 2026
Pages:
54-61
Received:
30 September 2026
Accepted:
13 October 2026
Published:
28 October 2026
Abstract: The volume of construction and demolition (C&D) waste generated worldwide continues to rise sharply, which undermines efforts to meet long-term sustainability targets. Converting demolished concrete into aggregate offers a practical route to limit landfill disposal and preserve natural raw materials. In Bangladesh, crushed brick chips are the conventional coarse aggregate for concrete, whereas demolished substructure elements such as pile caps usually contain stone chips and can therefore supply stone-based recycled concrete aggregate (RCA) of high strength. In this work, natural coarse aggregate (NCA) was substituted with stone-based RCA at levels of 0%, 20%, 40%, 60%, 80%, and 100%, and the resulting recycled aggregate concrete (RAC) was examined. The aim was to identify an acceptable RCA substitution level that does not impair concrete performance. Six batches of cylindrical specimens (100 mm × 200 mm) were prepared with a mix proportion of 1: 1.1: 3.1, designed following the British Standard method, and a constant w/c ratio of 0.50. Tests on the coarse aggregates indicated that the collected RCA was of better quality than the brick-based NCA, with a higher SSD unit weight (1493 kg/m3 versus 1338 kg/m3) and a much lower water absorption (10.32% versus 23.16%). Consequently, compressive strength rose progressively with RCA content up to 80% substitution, where it exceeded that of the control mix by 47%. At full (100%) substitution, the gain over the control dropped to 33.8%. This decline is linked to the larger quantity of old mortar attached to the aggregate surface, which produces a weaker interfacial transition zone (ITZ).
Abstract: The volume of construction and demolition (C&D) waste generated worldwide continues to rise sharply, which undermines efforts to meet long-term sustainability targets. Converting demolished concrete into aggregate offers a practical route to limit landfill disposal and preserve natural raw materials. In Bangladesh, crushed brick chips are the conve...
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