Search

• A timber system is proposed for the seismic retrofit of URM buildings. • Analytical equations are derived for design against different failure modes. • Wall in-plane and out-of-plane responses, diaphragms and connections are addressed. • The proposed equations are applied to case-study buildings and structural members. • Good agreement between analytical calculations and experimental data is shown. An innovative timber retrofit was investigated at the EUCENTRE and at the University of Pavia, Italy, as part of a comprehensive research campaign on the seismic vulnerability of existing unreinforced masonry buildings subjected to induced seismicity in The Netherlands. The retrofit system consists of timber frames, connected to the masonry piers and to the floor diaphragms, and oriented-strand board sheathing nailed to the frames and to flexible timber diaphragms. Starting from the main critical aspects observed in experimental tests, the proposed solution was conceived to enhance the in-plane and out-of-plane capacities of masonry piers, improve the overall wall-to-diaphragm connections, increase the floor diaphragm stiffness and strength, and allow possible integration with energy efficiency upgrades. This paper, the first of a series of two, focuses on the conceptual bases of the seismic retrofit system and on the analytical equations that can be used for the design of its components. Moreover, a step-by-step design procedure is presented to guide the reader through the application of these equations. A companion paper [1] will discuss the validation of the analytical formulation with the experimental data from quasi-static cyclic and dynamic shake-table tests on building components and complete specimens. [ABSTRACT FROM AUTHOR]

• A timber system is proposed for the seismic retrofit of URM buildings. • Analytical equations are derived for design against different failure modes. • Wall in-plane and out-of-plane responses, diaphragms and connections are addressed. • The proposed equations are applied to case-study buildings and structural members. • Good agreement between analytical calculations and experimental data is shown. This paper is the second of a series of two, discussing the analytical assessment of the seismic behavior of an innovative timber retrofit for unreinforced masonry structures. The retrofit system consists of timber frames, connected to the masonry piers and to the floor diaphragms, with oriented-strand board sheathing nailed to the frames and to flexible timber diaphragms. The companion paper [1] focused on the conceptual bases of the proposed solution, providing analytical equations for the design of its components, and a step-by-step design procedure for their practical application. In this paper, the proposed formulations are validated against the experimental data coming from in-plane quasi-static shear-compression tests on masonry piers and dynamic shake-table tests on a full-scale building prototype. These tests were performed on nominally-identical specimens in both bare and strengthened configurations, allowing a direct comparison between the experimental and calculated retrofit contribution. In particular, the analytical formulation was applied to reproduce the in-plane response of individual piers, to reproduce the base shear-interstory drift envelope of the building specimens, to assess the out-of-plane strength of walls, and to validate the flexible diaphragm enhancement. Overall, the proposed formulations revealed a good match with the observed retrofit performance and failure mechanisms. [ABSTRACT FROM AUTHOR]