Flexural Response and Failure Analysis of Solid and Hollow Core Concrete Beams with Additional Opening at Different Locations.

Ibrahim A Sharaky,Yasir M Alharthi,Ahmed S Elamary

doi:10.3390/ma14237203

Abstract

It is essential to make openings in structural concrete elements to accommodate mechanical and electrical needs. To study the effect of these openings on the performance of reinforced concrete (RC) elements, a numerical investigation was performed and validated using previous experimental work. The effect of the position and dimension of the opening and the beam length on the response of the beams, loads capacities, and failure modes was studied. The simulated RC beams showed different responses, loads capacities, and failure modes depending on the position and dimension of the opening. The transversal near support opening (TNSH) and longitudinal holes (LH) showed lower effects on the load capacities of the beams than the transversal near center opening (TNCH). The supreme reduction percentages of the load capacity (µu%) for beams with TNCH and TNSH were 37.21% and 30.34%, respectively (opening size = 150 × 150 mm2). In addition, the maximum µu% for beam with LH was 17.82% (opening size = 25% of the beam size). The TNSH with a width of less than 18.18% of the beam shear span (550 mm) had trivial effects on the beam’s load capacities (the maximum µu% = 1.26%). Although the beams with combined LH and TNCH or LH and TNSH showed different failure modes, they experienced nearly the same load reductions. Moreover, the length of the beam (solid or hollow) had a great effect on its failure mode and load capacity. Finally, equations were proposed and validated to calculate the yield load and post-cracking deflection for the concrete beams with a longitudinal opening.

Highlights

Hollow core concrete (HCC) beams are advantageous when compared to solid concrete beams due to the weight reduction that affects the transportation cost
The results revealed that the reinforced concrete (RC) beams that had a longitudinal circular opening failed by shear mode when tested with a shear span to effective depth (Lsh /d) ratio of 1.37, by flexure–shear mode when tested with (Lsh /d) ratio of 1.6–2.56, and by flexure mode when tested with (Lsh /d) ratio of 2.69
The results showed a reduction in the ultimate loads for the high-strength concrete (HSC) and ultra-high-performance concrete (UHPC) by 24% and 42%, respectively, in comparison to that for the solid beams

Summary

Introduction

Hollow core concrete (HCC) beams are advantageous when compared to solid concrete beams due to the weight reduction that affects the transportation cost. The required materials for HCC beams are significantly less than those needed for conventional beams, and they have the accessibility provision for passing electromechanical works. These advantages have motivated researchers to study the structural behavior of HCC beams under different loading conditions. When the beams are subjected to pure torsion, the obtained results verify that hollow and solid beams of the same materials and dimensions practically failed at the same loads, and the internal concrete core had minimum effect on their response [1,2,3]

Results

Discussion

Conclusion