Experimental study on shear performance of RC beams strengthened with NSM CFRP prestressed concrete prisms

This paper presents an experimental investigation of the shear performance of RC beams strengthened with near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) prestressed concrete prisms (PCPs). The shear behaviour of strengthened beams can be affected by several design variables. In this research, the effect of the following parameters were considered: the prestress level, inclination and spacing of the CFRP-PCPs, and material type of the prism. The control beam had conventional shear steel reinforcement only while the other seven beams were shear strengthened with CFRP-PCPs by varying design parameters mentioned above. All the beams were tested under monotonic loading until they reached the failure load. The experimental results showed that the NSM CFRP-PCPs strengthening technique improves the shear performance of the beams effectively. The strengthened beams that applied the CFRP-PCPs at an inclination of 45 • were more efficient in improving the shear capacity compared to vertical CFRP-PCPs. The shear capacity and deformation were enhanced with the increase of prestressing levels of CFRP rods and the decrease of CFRP-PCPs spacing. The failure modes of the strengthened beams were influenced mainly by the spacing and the inclination of the CFRP-PCPs. Moreover, the material type of the prism had little influence on the effectiveness of shear strengthening. The analytical model presented was developed to estimate the shear contribution of NSM CFRP-PCPs and the model was found to predict the shear capacity of the tested beams well

Effect of Concentrated Butt-Joints on Flexural Properties of Laminated Bamboo-Timber Flitch Beams

This paper presents the experimental and analytical studies to investigate the effect of concentrated butt-joints on the flexural properties of laminated bamboo-timber flitch beam (BTFB, or bio-flitch beam). The experimental results reveal that the concentrated butt-joints significantly reduce the flexural strength of the BTFB. They also suggest that the failure mechanism of the BTFB with or without concentrated butt-joints are completely different but less evidence shows an obvious effect of the butt-joints on the modulus of elasticity in bending. In addition, laminated bamboo lumber with concentrated butt-joints is found to be unsuitable for structural applications. The analytical predictions are in close agreement with the experimental results that demonstrate the potentials of the proposed analytical model as a forensic investigation instrument to estimate the strength reduction of the structure, if the butt-jointed laminated bamboo was, unfortunately, used in construction