International Concrete Abstracts Portal

Modular construction has been attracting attention worldwide as a promising solution to reduce construction time and labor demand. In this study, a new inter-module composite floor system that connects the upper module floor beams and lower module ceiling beams was experimentally and analytically investigated with an emphasis on vibration performance under service loading. First, the upper module floor of 2 m [6.56 ft] wide and 6 m [19.7 ft] long was fabricated as a composite system consisting of precast concrete (PC) panels, steel beams and ultra high-performance concrete (UHPC) connectors. Structural integrity between PC panels, steel beams and UHPC connectors were secured using grouting and topping mortar. Then, the lower module ceiling beams were connected to the upper module floor beams by fully tensioned high-tension bolts (i.e., slip-critical connection) to complete the inter-module composite floor. The vibration frequencies, damping ratio, and acceleration responses of the inter-module composite floors were measured from laboratory tests such as impact hammer, heel drop and walking tests, considering the number and location of the connecting bolts as the test parameter. The vibration characteristics of the inter-module composite floors were investigated further through finite element analysis. The measured and predicted vibration performances were compared with the acceptance criteria in AISC Design Guide 11 and ISO 10137.

Fiber-reinforced polymer-reinforced concrete (FRP-RC) structures have won researchers’ attention for decades as a considerable substitute due to their superb mechanical and non-mechanical properties. Despite the promising potential of concrete structures with glass FRP and basalt FRP that were shown by previous research, there are few specifications for the seismic design of FRP-RC structures to date due to limited research data on their seismic behavior. This paper focuses on the seismic performance of concrete columns with carbon fiber-reinforced polymer (CFRP) reinforcement by finite element modeling. The effect of longitudinal reinforcement type and ratio, stirrup spacing, concrete strength and axial load ratio are included in the parametric analysis in VecTor2. Properly designed CFRP-RC columns with good confinement generally reach high load-carrying capacity and deformation level, while high axial load could induce relatively severe damage. To verify these conclusions, seven full-scale columns are under construction and will be tested under combined lateral reversed cyclic loading and constant axial loading.

Developments in the prestressed concrete industry evolved to incorporate innovative design materials and strategies driven towards a more sustainable and durable infrastructure. With steel corrosion being the biggest durability issue for concrete bridges, FRP tendons have been gaining acceptance in modern prestressed technologies, as bonded or unbonded reinforcement, or as part of a “hybrid” system that combines unbonded CFRP tendons and bonded steel strands. Assessments of the efficacy of hybrid-steel beams, combining bonded and unbonded steel tendons. in the construction of segmental bridges and in retrofitting damaged members has been established by several researchers. However, limited research has been conducted on comparable hybrid prestressed beams combining CFRP and steel tendons (hybrid steel-cfrp beams). This paper provides an insight on the flexural behaviour of eighteen prestressed beams tested under third-point loading until failure with the emphasis on the tendon materials (i.e., CFRP and steel) and bonding condition (i.e., bonded, unbonded). In addition, a comprehensive finite element analysis of the beams’ overall behaviour following the trussed-beam methodology is conducted and compared with the experimental results. Results show that hybrid beams, utilizing CFRP as the unbonded element maintained comparable performance when compared to hybrid steel beams. The results presented in this paper aim to expand the use of hybrid tendons and facilitate their incorporation into standard design provisions and guidelines.

Concrete beam-column joints are critical elements in the seismic performance of reinforced concrete (RC) structures. The use of carbon fiber-reinforced polymer (CFRP) reinforcement in these joints has gained attention due to its superior mechanical properties and corrosion resistance. This paper presents a comprehensive study of the seismic performance of CFRP-reinforced concrete beam-column joints, focusing on the development of a suitable formula for estimating the seismic shear capacity. Utilizing a finite element analysis (FEA) that was both developed and validated using pre-existing test data, a comprehensive parametric study was undertaken to explore the impact of several factors. These factors encompassed axial load, longitudinal reinforcement ratio, and transverse reinforcement ratio, and their effects on the seismic performance of CFRP-RC joints were thoroughly investigated. Eventually, a suitable formula was proposed for estimating the seismic shear capacity of CFRP-RC joints. Research results will lead in a better understanding of the seismic behavior of CFRP-reinforced concrete beam-column joints, which will consequently guide the design and analysis of CFRP-reinforced concrete structures for enhanced seismic performance.

The study delves into modeling the interface between Fiber-Reinforced Polymer (FRP) and concrete, with a specific emphasis on simulating the gradual deterioration of bond strength. A model rooted in continuum damage mechanics is integrated with an empirically derived relationship to address interfacial shear failure. Material models are defined for the concrete, the externally bonded FRP reinforcement, and the adhesive layer. These material models are implemented in finite element simulations, replicating experimental setups widely used to investigate the FRP-concrete interface. Key results are reported and discussed. More precisely, the numerically obtained load-slip relationships for the interface and visualizations of the damaged zones in concrete are provided. The numerical results are in close agreement with existing experimental data. The finite element analyses suggest that concrete degradation is not limited to the areas near the adhesive joint. This implies that the adhesive joint could influence the overall behavior of the structural elements, even when debonding failures are prevented by anchorage devices.