Shape memory alloys (SMAs) are metallic materials with great potential to enhance civil engineering structures. They are often referred to as smart materials. A basic description of their highly non-linear material behaviour in terms of shape memory effect, superelasticity, martensite damping and variable stiffness is given in this aiticle. It is followed by a brief introduction to Ni-Ti and Fe-Mn-Si SMAs. Preexisting and new applications in the fields of damping, active vibration control and prestressing or posttensioning of struchues with fibres and tendons are being reviewed with regard to civil engineering. Furthermore, the relatively high costs ai1d the problem of retaining posttensioning forces when using some types of SMAs are nained. In this regard is Fe-Mn-Si-Cr discussed as potential low cost SMA. A simple model for calculating the activation times of resistive heated SMA actuators or springs is presented. The results and measured data lead to fmther constrictions. Finally, new ideas for using SMAs in civil engineering structures are proposed in this aiticle such as an improved concept for the active confinement of concrete members. This article is to introduce civil engineers to the world of shape memory alloys and invite them to contribute to their wider use in civil engineering structures.

Purpose: Life Cycle Assessment (LCA) is a valuable method for evaluating the environmental impact of buildings. However, it is only rarely applied in the building design process, as it is complex and time-consuming. There is high demand for simplified approaches that are applicable by architects without detailed knowledge of LCA. Therefore, this paper presents a parametric LCA approach, which allows architects to efficiently reduce the environmental impact of building designs. Methods: To develop this parametric approach, first of all the requirements for designintegrated LCA are analysed. Based on these requirements, assumptions to simplify the required data input are made and a parametric model is established. The model parametrizes all input, including building geometry, materials, and boundary conditions, and calculates the LCA in real-time. The parametric approach possesses the advantage that input parameters can be adjusted easily and quickly. The architect has two options to improve the design: either through manually changing geometry, building materials, and building services, or through the use of an optimization solver. The parametric model was implemented in a parametric design software for the purpose of applying the method to two examples. Results and discussion: The application is demonstrated using two examples: the design of a new residential building and the retrofitting of a single-family house. In both examples the goal is to find a solution with minimum environmental impact. In the first example, the parametric method is used to manually compare geometric design variants. The LCA is calculated based on assumptions for materials and building services. In the second example, evolutionary algorithms are employed to find the optimum combination of insulation material, heating system, and windows for retrofitting. The results indicate that there is not one optimum insulation thickness, but many optima, depending on the individual boundary conditions and the chosen environmental indicator. Conclusion: By incorporating a simplified LCA into the design process, the additional effort of performing LCA is minimized. The parametric approach allows the architect to focus on his main task of designing the building and finally makes LCA an applicable parameter for design optimization in architectural practice. In future, further analyses can be integrated and the method could be extended for Life Cycle Costing. Response to Reviewers: Dear reviewers, thank you very much for your comments. I responded to them in the attached file.

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The mean free path of excess vacancies that are generated during electromigration in silver has been determined employing a combined electromigration diffusion technique. The method is based on the assumption that during electromigration a steady-state excess vacancy distribution exists. The latter is determined by a measurement of diffusion enhancements of copper in silver at different positions along the electric field gradient. Under certain conditions that are expected to be fulfilled in our experiments an evaluation of the measured diffusion enhancements by means of the steady-state theory yields the mean square free paths of the excess vacancies. They are found to be between and .