231 publications from this institution
Studies of prefabricated segmental concrete beams (PSCBs) under impact loading are extremely scarce, especially those constructed with geopolymer concrete (GPC) and non-corrodible fibre-reinforced polymer (FRP) tendons. This study conducts experimental tests to explore the impact performance of PSCBs made of GPC and post-tensioned with FRP/steel tendons. An analytical model for predicting the impact response of PSCBs is also derived. The test results show that different from monolithic beams, the damage in PSCBs is mainly concentrated around segment joints due to joint openings that led to the beam failure by concrete spalling. The PSCBs with carbon-FRP tendons and steel tendons show similar damage patterns. Under a similar condition, the difference in the displacement response of these two beams is less than 4%. A similar trend in the generated impact load and reaction force is also observed. These two beams reach the first peak and plateau region of impact load and the maximum reaction force at similar times. Overall, the PSCB with carbon-FRP and steel tendons exhibits comparable impact performances. These results manifest the applicability of carbon-FRP tendons in PSCBs against impact loads, as a feasible and durable alternative to conventional steel tendons. Furthermore, theoretical derivations are conducted to derive a simplified analytical model for predicting the impact response of simply supported segmental beams. This analytical model is based on a mass-spring-damper system and a nonlinear sectional analysis, considering the local response at the impact zone, global elastic and inelastic behaviours of segmental beams, imperfections in segment interfaces, nonlinear behaviours of material properties and strain rate effects. The proposed analytical model can facilitate the analysis and design of segmental beams.
The use of low-emission geopolymer concrete (GPC) and noncorrodible basalt-fiber-reinforced polymer (BFRP) bars is an effective strategy in the bid for net zero emissions and making sustainable and durable structures. To date, however, there have been no studies on the impact response of prefabricated/precast segmental concrete beams (PSCBs) constructed using GPC and BFRP bars. This experimental study, therefore, was intended to partially fill this knowledge gap. The key objectives were to investigate the impact behavior of the segmental versus traditional monolithic beams, the effect of impact location, and the performance of GPC versus ordinary Portland cement (OPC) concrete beams. The test results showed that, with the energy absorption capability derived from the opening and sliding of joints, the PSCB experienced less damage than its monolithic counterpart under similar impact conditions. The joints, however, reduced the global stiffness of the PSCB, resulting in the PSCB having a higher displacement, lower impact and reaction forces, but a longer impact force duration and greater impulse, compared to the corresponding monolithic beam. Under the impact loads, the PSCB had a higher tendon force but smaller reinforcement strain than the monolithic beam. Impacting at the joints mobilized the energy absorption capability more effectively, resulting in a reduction in impact-induced damage. The impact performance of both the monolithic and segmental GPC beams was quite similar to that of their OPC counterparts. Thus, GPC can be adopted as a sustainable alternative to OPC in the construction of concrete structures against impact loads. In this study, a three-dimensional finite-element model was also developed in order to obtain a better understanding of the impact behavior of segmental and monolithic beams.
The paper uses the membrane hypothesis to formulate the confining behavior of fiber-reinforced polymer (FRP) confined rectangular columns. A model was developed to calculate the strength of FRP confined rectangular concrete columns. The model was verified using a database of 190 FRP confined rectangular concrete columns. The database covers unconfined concrete strength between 18.3 and 55.2 MPa, and specimens with dimensions ranging from 79–305 mm and 100–305 mm for short and long sides, respectively. The performance of the proposed model shows a very good correlation with the experimental results. In addition, the strain distribution of FRP around the circumference of the rectangular sections was examined to propose an equation for predicting the actual rupture strain of FRP. The minimum corner radius of the sections is also recommended to achieve sufficient confinement.
