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Abstract: The paper compares the accuracy and stability of implicit and explicit stress integration schemes applied to the Barcelona Basic Model. In addition, the effect of the integration scheme on the convergence of Newton–Raphson algorithm is studied. By running a Newton–Raphson algorithm for a single stress point, the number of iterations required to reach convergence gives some insight on the convergence of the finite element solution at the global level. The explicit algorithms tested incorporate substepping with error control and are based on Runge–Kutta methods of different orders or on the Richardson extrapolation method. The implicit return-mapping algorithms follow the procedures of Simo and Hughes and Hofmann . [Copyright &y& Elsevier]

Abstract: Many urban areas suffer water scarcity but paradoxically, a local source of water such as rainwater is mostly treated as a risk rather than as a valuable resource. Scepticism regarding the use of rainwater harvesting technologies still prevails today, particularly in low precipitation areas. However, some regions such as the Metropolitan Area of Barcelona (MAB) have started to promote the use of rainwater through specific regulations and incentives. This paper aims to examine the use of rainwater harvesting in the two main types of buildings prevalent in the MAB by analysing users’ practices and perceptions, drinking water savings and economic costs. Despite low precipitation inputs and a high variability of precipitation, daily balances show that toilet flushing demand of a single family house can be practically met with a relatively small tank. Rooftop rainwater can also meet more than 60% of the landscape irrigation demand in both single and multi-family buildings. The main drawback is the long pay-back period that rainwater harvesting systems present today. Nevertheless, it is remarkable that in multi-family buildings residents usually take no notice of the costs associated with the system. In contrast, benefits for the whole society are usually much more appreciated. Users’ reactions and their level of satisfaction towards rainwater harvesting systems suggest that both regulations and subsidies are good strategies to advocate and expand rainwater harvesting technologies in residential areas. However, a multidirectional learning environment needs to be promoted to ensure a proper use of rainwater harvesting systems and risk minimisation. [Copyright &y& Elsevier]