Flexure behavior of hollow steel beams strengthening with ferrocement

Abstract

Experimental and numerical studies are carried out to investigate the flexural behavior of precast lightweight composite beams composed of a hollow steel beam strengthened with a ferrocement layer. This composite beam comprises of a slender cold-formed hollow section of dimension (140 × 180 mm) of different thicknesses surrounded by a ferrocement layer. This composite beam is named a precast ferrocement cold-formed hollow section (FCH). Nine beams with a span of 1500 mm were tested under a four-point bending system to evaluate their flexural strength. Four different parameters have been examined, which are the spacing of shear connectors, ferrocement thickness, hollow steel section thickness, and the effect of surface friction. The test results showed that the presence of 30 mm ferrocement layer increased the capacity by 18% compared with the control specimen. The presence of shear connectors increases the capacity by 30%. Increasing the steel cross-section thicknesses increase section capacity by 16–33% and finally, increasing the surface friction has a very small effect on the section capacity, which can be neglected. The finite element models were developed and validated by the test results; results show a close agreement between the experimental and finite element results. Extensive parameters were investigated, which were mortar compressive strength (f'c) and the position of the shear connectors. The results indicated that increasing mortar strength increases section capacity ranging between 11% and 18%. The presence of a shear connector in the web and the lower flange of the hollow section have an insignificant effect.