Dynamic Optimization of High Rise Timber-Hybrid Buildings A FEM study of the effect on the dynamic response of com bining timber and concrete in a high rise building

Abstract

In recent years, the popularity of building high rise timber buildings has increased. Some reasons for using timber in high rise structural systems are for environmental, architectural and marketing aspects. Timber is a light-weight building material which can result in large dynamic effects due to wind, causing comfort problems in the buildings. One solution is to build timber-hybrid structures that utilize other structural materials in combination with timber. A study is done with focus on dynamic responses in high rise timber and timber-hybrid buildings to optimize the combination of timber and concrete. The aim of the project is to get a better understanding of the effect on added stiffness and mass by utilizing concrete as material in high rise timber-hybrid buildings and how it influences the dynamic response. The work is carried out by using FE analyses to determine the dynamic properties of different timber-hybrid buildings. The FEM study is performed using the software FEM-Design. Using results from the FEM study, calculations methods from EKS 12 and Eurocode 1-4 are used to determine the accelerations in buildings caused by wind loads. The results are compared to the human comfort requirements of ISO 10137 and ISO 6897. The results show that replacing timber structural elements with concrete is an effective way of improving dynamic properties in high rise timber buildings. It is shown that concrete floors are more efficient at the top of the building, where the mass has the largest influence. It is also shown that concrete cores are effective throughout the full height of the building. The most optimal solutions are found when a concrete core and concrete floors were utilized in the structural systems. The CLT structural system can be built with less concrete than the Glulam column system, however the CLT building requires more timber. A building with both systems combined can be used to increase the building height and reduce concrete volume compared to just using one system. A tuned mass damper is shown to be a potential solution to dynamic problems in high rise timber hybrid buildings.