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Due to the dynamic characteristics of natural events, innovative concepts and engineered systems for energy dissipation in buildings have recently been proposed. Several SMA-based original systems and devices have been designed to dissipate a part of the seismic energy and to reduce earthquake forces acting on the structure. SMAs have been integrated within these devices in many possible shapes and configurations, such as single and stranded wires, ribbons, strips, tubing, and bars, adding excellent key features to civil engineering applications. A collection of such SMA-based applications in buildings is presented, subdivided in sections based on the practical domain.

Although the enormous potential, to date, only few effective real-scale retrofits of existing heritage structures have been realized through the implementation of SMA-based systems, mainly to repair and strengthen historical structures after the seismic damage. Compared with traditional steel systems, SMAbased retrofits are able to reduce acceleration and forces, increasing the seismic efficiency of the 20 structure and reducing its vulnerability. A review of SMA-based retrofitting techniques is presented, including the exemplary case study of the bell tower of the S. Giorgio (Trignano) church: the retrofitted monumental building has not suffered from significant damages after subsequent earthquakes.

Non-prismatic beams are widely employed in strategic structures like bridges and sport arenas, requiring accurate analyses for a reliable and effective design. Unfortunately, features of non-prismatic beams lead their modeling to be a non-trivial task: (i) variations of both cross-section area and second moment of area impede an easy computation of analytical solutions compelling to use approximated methods; (ii) stress distributions in prismatic and non-prismatic beams are substantially different, as proved by analytical results available since the beginning of the past century; and (iii) the peculiar stress distribution in non-prismatic beams entails complicated constitutive relations, as highlighted in recent publications. Usually, commercial software does not properly account for all the features of non-prismatic beams, leading to inconsistent structural analyses, erroneous estimations of the stress distribution, and -consequently- coarse predictions of the structural element strength. The present paper proposes a strategy to effectively overcome the above-mentioned problems. We derive an accurate analytical model for 2D non-prismatic beams, able to handle the non-trivial stress distribution and the complicated constitutive relations. Thereafter, we compute both homogeneous and particular solutions using the symbolic calculus software MAPLE and we analytically define the Finite Element (FE) stiffness matrix for a planar, symmetric, linearly-tapered beam. Finally, we compare the proposed FE and SAP2000 solutions, considering several beams with different geometries, loads, and constraints. Numerical results highlight the reliability of the proposed modeling strategy, since the resulting FE consistently handles all the critical issues of non-prismatic beams with an extremely low computational cost. Conversely, SAP2000 solution remarks the need of ad hoc analysis tools and modeling strategies to be used for the design of non-prismatic structural elements.

Different procedures for assessing the robustness of a reinforced concrete (RC) frame under progressive damage are proposed and compared. The removal of a column in a RC frame structure is modeled with a commercial nonlinear finite element software according to three alternative strategies: (i) reduction of mechanical properties of the damaged column, (ii) incremental loading of the structure after total removal of the damaged column, and (iii) incremental unloading of internal forces on the damaged column. Nonlinear analysis is performed under a prescribed load combination on three RC frames designed with three Italian building codes in force in different periods. Despite the differences in the strategies for damage modeling, similarities between structural response predictions are highlighted. In addition, it is shown that seismic design provisions for RC structures increase the ductility of the structure but do not necessarily guarantee robustness to progressive collapse scenarios.