Horisontalstabilisering av KL-trä- och betongskontorshus vid seismiska belastningar : En jämförelse av förbandinverkan i KL-trä och betong för flervåningskontorshus i jordbävningsutsatta områden

Sammanfattning

This thesis investigates and compares the horizontal stabilization and seismic performance of office buildings constructed with cross-laminated timber (CLT) and reinforced concrete. The study was motivated by the 2023 earthquake in Kahramanmaraş, Turkey, where thousands of concrete buildings collapsed despite compliance with modern building codes. This disaster has highlighted the urgent need for safer and more sustainable structural solutions in seismically active regions. CLT has emerged in recent years as a promising lightweight, flexible, and sustainable alternative to traditional concrete. The aim of the study is to assess how different types of connections affect a building’s ability to resist seismic loads and to evaluate whether CLT can serve as a technically viable substitute for concrete. Two office building models with identical dimensions were developed, one featuring a CLT frame and the other a concrete frame. The models were analyzed using the structural software RFEM 6, where response spectrum analysis was performed under varying base accelerations and behavior factors. Results indicate that connection stiffness and ductility significantly influence seismic performance. In the CLT building, increasing connection stiffness led to substantial reductions in deformation, reaching near zero levels in some cases. In contrast, the concrete structure exhibited notable residual deformation even with high connection stiffness, primarily due to its higher mass and limited ductility. Under high seismic loads, both buildings satisfied the interstory drift limits specified by Eurocode 8, though the concrete building approached the threshold, while the CLT model remained well within safe limits. A higher behavior factor reduced deformations by approximately 70%, demonstrating the critical role of ductility and energy dissipation in seismic design. Overall, the study concludes that CLT frames, when equipped with properly designed connections, offer a feasible alternative to concrete structures in earthquake-prone areas. Its low weight and high strength make the system particularly suitable for reducing mass-related seismic loads. While concrete constructions demand more robust joints and precisely detailed reinforcement to achieve comparable performance.