Browsing by Author "Rendel, Michael"

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    Design, testing and implementation of TADAS devices in three RC buildings with shear walls and coupling beams
    (2017) Zemp, René; Urrutia, R.C.; Rendel, Michael; Cavalla, G.; Llera Martin, Juan Carlos de la
    A Triangular Added Damping and Stiffness (TADAS) device is an economic energy dissipation solution to improve the earthquake performance of flexible buildings. TADAS devices have a very stable force displacement constitutive relationship and a high capability of energy dissipation. This research proposes the use of TADAS dampers in coupling beams or lintels between reinforced concrete (RC) shear walls. Coupling beams are typical of RC shear wall buildings with flat slabs and staircase and elevator shear wall cores. The proposed solution integrates into the structure without a relevant impact on the architecture, a significant advantage over other energy dissipation solutions. In this article, three different building applications with TADAS devices are presented. Numerical simulations for these buildings show that drift, displacement, and base shear reductions typically range between 10% and 30%. An effective TADAS design balances stiffness, energy dissipation, and fatigue life of the device under cyclic plastic deformations. Fatigue life for mild steel was determined experimentally and the TADAS devices were designed with a simple model validated by testing of single triangular plates. As expected for rate independent plasticity, tests at different frequencies showed negligible performance variations with deformation velocity. Several TADAS prototypes were cyclically tested and their results are reported in this article. In an effort to analyze the performance and stiffness of the connection between the damper and RC beam, the prototype tests include a section of the capacity-designed concrete beam with the device under simulated as-built conditions. The final design also allows replacing the damper, if needed, after a strong earthquake, and considers an installation procedure that minimizes slip in the connection to the concrete beam.
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    Inelastic dynamic analysis of a prestressed reinforced concrete frame
    (Taylor & Francis Group, 2016) Vásquez González, Jorge Andrés; Llera Martín, Juan Carlos de la; Rendel, Michael
    Customary Seismic design assumes a reduced design spectrum with a certain ductility level of the structure. Although proven successful, the design method provides little information about the inelastic behavior of a structure, which is expected to be large in severe earthquakes. This study deals with the inelastic dynamic response analysis of a large prestressed building to be constructed in Chile. Because of regularity of the structure, a 2D reinforced concrete frame was modeled using fiber elements regularized with a modified stress-strain constitutive relationship using the software Opensees. Therefore, damage may occur anywhere along the element characterized by variable reinforcing steel and internal forces. Results of the inelastic analysis show that inelastic deformations localize in a few places around the nodes, but the building is able to withstand a maximum credible earthquake demand without collapse.