In this study, support vector machine (SVM) and Gaussian process regression (GPR) models were employed to analyse different rubbercrete compressive strength data collected from the literature. The compressive strength data at 28 days ranged from 4 to 65 MPa in reference to rubbercrete mixtures, where the fine aggregates (sand fraction) were substituted with rubber aggregates in a range from 0% to 100% of the volume. It was observed that the GPR model yielded good results compared to the SVM model in rubbercrete strength prediction. Two strength reduction factor (SRF) equations were developed based on the GPR model results. These SRF equations can be used to estimate the compressive strength reduction in rubbercrete mixtures; the equations are provided. A sensitivity analysis was also performed to evaluate the influence of the w/c ratio on the compressive strength of the rubbercrete mixtures.

This study evaluates the compatibility of repair materials for concrete bridge decks. A new compatibility test set-up was designed and tested based on the concrete bridge deck cracking and delamination mechanism theory. The repair materials used in this study include lab formulated inorganic nano-aluminum silicates and commercially available organic two-part epoxy systems. Two different lab test-setups are proposed in this study: a prototype and a full-scale test. The developed test procedures were effective in communicating results in terms of compatibility of material properties, performance and quality. The prototype beams test can successfully serve as a small scale screening test providing insights on materials selection for the full-scale beam tests. The full-scale beams demonstrated the compatibility of the repaired system by providing data on authentic field conditions. Based on the observations it can be concluded that the proposed test setup is effective in examining the concrete bridge deck repair materials performance and selection, and compatibility in terms of mechanical properties and further guarantee the repaired structure safety.

This study aims to develop and evaluate vibration-based piezoelectric energy harvesters for generating power from a bridge structure. New designs of multiple-degree-of-freedom (DOF) cantilevers were proposed and evaluated in a laboratory and on a full-scale bridge. It was found that all cantilever designs showed potential of generating 35 V voltage outputs under a simple sinusoidal vibration scenario in the laboratory. Field testing results showed that the match between the vibration frequencies of bridge structure and the resonant frequencies of cantilevers significantly affected the voltage output from the piezoelectric energy harvester under moving tire loads. Through adding more DOF on the same cantilever, the voltage attenuation from peaks generated by the cantilever turned to be less significant after each load passing, leading to greater energy outputs in some cases. With adjusting the mass combination in the 3-DOF cantilever design, the voltage output and energy production reached 11.1 V and 58.2 μJ under one single loading pulse, respectively, which was higher than 9.2 V and 14.9 μJ obtained from the best scenario of 1-DOF cantilevers. The study findings indicate the potential of developing multi-band piezoelectric energy harvesters for harvesting energy from bridge vibrations.