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Biochar has shown great promise in producing low-cost low-carbon concrete for civil infrastructure applications. However, there is limited research comparing the use of pristine and contaminated biochar in concrete. This paper presents comprehensive laboratory experiments and three-dimensional nonlinear finite element analysis on the mechanical, economical, and environmental performance of reinforced concrete beams made using concrete blended with biochar generated from vetiver grass roots after the roots were used in an oil extraction process. Both pristine biochar and biochar that were used to treat wastewater through adsorbing heavy metals (100 mg/L of Pb, Cu, Cd, and Zn) were investigated. The biochar was used to replace up to 6% Portland cement in concrete. Laboratory experiments were conducted to characterize the workability, mechanical properties, shrinkage, and leaching potential of the concrete blended with biochar. The results showed that using biochar could increase the compressive strengths and reduce the shrinkage of concrete without causing a leaching problem. The results from finite element analysis of the reinforced concrete beams showed that the use of biochar was able to increase the flexural performance of the beams as well as their economic and environmental performance. This research will promote the development and structural applications of low-cost low-carbon concrete.

This paper describes an investigation carried out on the behaviour of buildings with a dual lateral load-resisting system, comprising a reinforced concrete (RC) moment frame and steel plate shear walls (SPSW), subject to near-fault (NF) and far-fault (FF) earthquakes. Experimental validation of a one-bay, three-storey, RC frame with SPSWs was done using structural analysis software. The seismic performance of four buildings with various numbers of storeys was then compared using finite-element software. The non-linear dynamic behaviour of the four building was also modelled. Based on the results, it was found that the standard seismic design spectrum defined by Iranian Code of Practice for Seismic Resistant Design of Buildings does not satisfy all structural demands developed by NF earthquakes. The spectrum should be modified, especially for areas near active faults. The results also revealed that the impact of FF earthquakes on low- to mid-rise structures is more profound compared to that of NF earthquakes. Conversely, it was also found that NF earthquakes have greater impacts on taller buildings than that of the FF motions.