PSI - Issue 44

Agnese Natali et al. / Procedia Structural Integrity 44 (2023) 2334–2341 Agnese Natali, Francesco Morelli / Structural Integrity Procedia 00 (2022) 000–000

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4. Conclusions In this paper, a novel design approach – named “Over-resistant Connection Strategy” - with experimental validation for seismic resistant Automated Rack Supported Warehouses (ARSWs) is presented. This new method is based on concentrating dissipation in diagonal elements, which are arranged in the X tension-only structural scheme. The core of the approach is the design of the dissipative element and of its connection, which must be over-resistant with respect to the brace. This is hard to be obtained for ARSW’s upright-to-diagonal connections, whose resistance is led by bearing due to the very low thicknesses involved. To this purpose, local reduced sections are introduced in the diagonal, which surely may allow the over-resistance of connection but induce some weakening in the diagonal, affecting the behaviour in compression. After numerical simulations to evaluate the possible better layouts of the reduced sections to obtain a good performance in compression, these layouts are applied in cold-formed diagonals typically used for ARSWs’ racks and tested under monotonic tensile and compression load, and also under cyclic load. The tests results show a quite good behaviour under tensile monotonic load, with concentration of dissipation in the reduced sections closest to connections, and consequent limited involvement of the other reduced sections. The performance in compression is good, with global buckling mode anticipating the local one in the most cases (only the L4 layouts, with longer reduced parts, exhibits immediately local buckling), which is one of the goals in the optimization of the layout of the reduced sections. Under cyclic load, a good correspondence with tensile compression curves from monotonic tests can be observed, with no degradation in terms of resistance and a slight one in terms of stiffness. Some of the specimens fail under tensile force, in the reduced section which experienced local buckling, due little cracks that may appear during the loading-unloading cycles. In any case, damage in connection is not detected in any tests. This proves that the formulas for the design of the over-resistance of connection guarantee the desired behaviour. In the next steps, a further optimization of the layouts may be carried out, to limit the effects of local buckling in the cyclic performance and to better distribute dissipation along the length of the elements. Then, the second-step optimized layouts will be used for the numerical model of the whole ARSW structure to assess the global performance of the structure. The research conducted is carried out in the STEELWAR research project, which is founded by the European Commission, Research Fund for Coal and Steel, which is gratefully acknowledged. References BS EN 16681:2016 Steel static storage systems. Adjustable pallet racking systems. Principles for seismic design, 2016. Braconi, A., Caprili, S., Degee, H., Guendel, M., Hjaij, M., Hoffmeister, B., Karamanos, S. A., Rinaldi, V., Salvatore, W., 2015. Efficiency of Eurocode 8 design rules for steel and steel-concrete composite structures. Journal of Constructional Steel Research 112, 108–129. Caprili S., Mattei F., Salvatore, W., 2022. Seismic performance of innovative dissipative replaceable components for steel braced frame (DRBRC). The 8th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2022). Caprili, S., Morelli, F., Salvatore, W., and Natali, A., 2018. Design and Analysis of Automated Rack Supported Warehouses. The Open Civil Engineering Journal, 12(1), 150–166. EN 1993-1-3:2006 Eurocode 3: Design of steel structures - Part 1-3: General rules - Supplementary rules for cold-formed members and sheeting, 2006. EN 1998-1:2004: Eurocode 8: Design of structures for earthquake resistance – Part 1: General rules, seismic actions and rules for buildings., 2004. Haque, A. B. M. R., and Alam, M. S., 2015. Preliminary Investigation on the Overstrength and Force Reduction Factors for Industrial Rack Clad Buildings. Moen, C. D., and Schafer, B. W., 2009. Elastic buckling of thin plates with holes in compression or bending. Thin-Walled Structures, 47(12), 1597–1607. Morelli, F., Piscini, A., Salvatore, W., 2019. Development of an asymmetric re-centering dissipative device. Journal of Constructional Steel Research 17, 227-243. Morelli, F., Piscini, A., Salvatore, W., 2016. Seismic retrofit of an industrial structure through an innovative self-centering hysteretic damper: Modelling, analysis and optimization. VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2022). Natali, A., Morelli, F., and Salvatore, W., 2022. Influence of the design parameters on the current seismic design approach for Automated Rack Supported Warehouses. 7h World Congress on Civil, Structural, and Environmental Engineering (CSEE’22). Natali, A., Morelli, F., and Salvatore, W., 2022a. On the Seismic Design and Behavior of Automated Rack Supported Warehouse. DOI: 10.21203/rs.3.rs-1577721/v1 (Under review). Natali, A., Morelli, F., and Salvatore, W., 2022b. Seismic performance of currently designed Automated Rack Supported Warehouses. 7h World Congress on Civil, Structural, and Environmental Engineering (CSEE’22). Natali, A., Morelli, F. and Salvatore, W., 2022c. Seismic performance of dissipative automated rack supported warehouses. The 8th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2022).