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.
Basalt fiber-reinforced polymer (BFRP) has been applied for strengthening concrete structures. However, studies on reinforced concrete (RC) slabs strengthened by BFRP strips under impact loads are limited in open literature. This study investigates the efficiency of using BFRP strips with various strengthening layouts and anchoring schemes on the impact resistance of RC slabs. A total of 11 two-way square slabs were prepared and tested, including one reference specimen without strengthening and ten slabs strengthened with BFRP strips and/or anchors. The RC slabs were impacted by a drop weight with increasing height until slab failure. The observed failure modes include punching shear failure, BFRP sheet debonding and reinforcement fracture. The failure modes and the effects of using various strengthening schemes on the impact resistant capacity of RC slabs were examined. The quantitative measurements, such as impact velocity, indentation depth and diameter, were compared and discussed. In addition, numerical studies were carried out by using LS-DYNA to simulate the impact tests of RC slabs with and without BFRP strengthening. With the calibrated numerical model, the impact behavior of slabs with various dimensions and strengthening layouts under different impact intensities can be predicted with good accuracy.
