231 publications from this institution
This study investigates the axial impact resistance and energy absorption of rubberized concrete with/without fiber-reinforced polymer confinement. The impact tests were carried out using an instrumented drop-weight testing apparatus. The experimental results have shown that rubberized concrete significantly reduced the maximum impact force of up to 50% and extended the impact duration. These characteristics make rubberized concrete a promising material for protective structures and particularly for future sustainable construction of rigid roadside barriers. Glass fiber–reinforced polymer confinement is a very effective method to improve the impact resistance for both conventional concrete and particularly for rubberized concrete. It was found that the rubberized concrete reduced the maximum impact force so that it transferred a lower force to a protected structure as well as a lower rebound force, which is desirable for protection of passengers in an incident of vehicle collision. Interestingly, the rubberized concrete showed a lower energy absorption capacity as compared to conventional concrete, where the exact reason for this is unknown to the authors. Therefore, further research is sought to provide more understanding of the response of rubberized concrete under impact and improve its energy absorption. This study explored experimentally the use of rubberized concrete as a promising sustainable construction material for applications to construction of columns in buildings located in seismic active zones or subjected to terrorist attack, security bollards and rigid road side barriers.
This study proposes the use of artificial neural networks (ANNs) to calculate the compressive strength and strain of fiber reinforced polymer (FRP)–confined square/rectangular columns. Modeling results have shown that the two proposed ANN models fit the testing data very well. Specifically, the average absolute errors of the two proposed models are less than 5%. The ANNs were trained, validated, and tested on two databases. The first database contains the experimental compressive strength results of 104 FRP confined rectangular concrete columns. The second database consists of the experimental compressive strain of 69 FRP confined square concrete columns. Furthermore, this study proposes a new potential approach to generate a user-friendly equation from a trained ANN model. The proposed equations estimate the compressive strength/strain with small error. As such, the equations could be easily used in engineering design instead of the invisible processes inside the ANN.
This paper investigates the effect of using alternative cementitious constituents on the compressive performance of Ultra-High-Performance Concrete (UHPC) for both static and dynamic conditions. The grounded blast furnace slag (GBFS) and rice husk ash (RHA) with different portions were used to replace 30% ordinary Portland cement (OPC) of a reference mix (UHPC-R1). Two alternative UHPC mixes including an UHPC mix with 30% GBFS mix (UHPC-AC1) and an UHPC mix with 15% GBFS and 15% RHA mix (UHPC-AC2) were considered. The quasi-static compressive strength and dynamic compressive strength of the proposed UHPC mixes were then determined using a compression testing machine and a Split Hopkinson Pressure Bar, respectively. The results indicated that UHPC-AC1 and UHPC-AC2 yielded a comparable performance compared to the reference mix UHPC-R1. In particular, the static compressive strength of UHPC-AC1 and UHPC-AC2 mixes were found to only be 5% and 10% less than those of the UHPC-R1 mix, respectively. In addition, the study also found that UHPC-AC1 and UHPC-AC2 achieved a similar dynamic compressive strength compared to the UHPC-R1, and the compressive strength of UHPC-AC1 and UHPC-AC2 were not strain rate sensitive. For the environmental aspect, UHPC-AC1 and UHPC-AC2 have a lower embedded CO 2 emission index compared to the reference UHPC-R1.
Abstract Steel fiber reinforced concrete (SFRC) structures have been widely adopted and attracted great research attention due to their excellent performance in resisting tension and flexure bending. However, the existing analytical and numerical analyses of SFRC structures rely mainly on the experimental data of material tests, thereby being suitable for a case‐by‐case basis. This is due to the lack of a general and reliable constitutive material model for SFRC, which analytically considers the fiber‐dependent parameters such as fiber geometry, fiber stiffness, and interface properties of fibers and concrete matrix. This study presents an approach to modify the concrete plastic damage model to represent the SFRC material constitutive relations for simulating the structural behavior of SFRC. In this approach, the general procedure to integrate the bridging effect of fibers through the pull‐out mechanism into the constitutive relation of SFRC was proposed. The comparison between the numerical and experimental results was conducted to verify the reliability of the proposed model. The results demonstrated the proposed model could well represent the material performance of SFRC and the numerical simulations could capture reasonably the effect of the volume fraction, geometry, and properties of fibers on the structural response of SFRC.
