Dynamic Evaluation of a Nine-Story Timber-Concrete Hybrid Building during construction

Abstract

Timber-concrete hybrid buildings are an innovative solution to increase the amount of timber materials used in modern buildings. This study presents a dynamic evaluation of a nine-story timber-concrete hybrid residential building during construction. The building consists of a seven-story structure in cross-laminated timber (CLT) on top of two stories in concrete. Ambient vibration tests were conducted seven times during the 13-month construction period, including tests with only the structural elements in place and tests of the finished building with the façade, non-structural walls, and other internal finishing. The results show a clear decrease in the natural frequencies of the building as the building gets higher and more elements are installed. However, a slight increase in the natural frequency was observed following the installation of the non-structural walls in the final construction stage. A corresponding finite element analysis is presented for each test, providing additional insights into the parameters typically used in the structural design process. The study demonstrates the importance of properly selecting reduction factors for CLT elements in a dynamic finite element analysis. It also shows the importance of considering non-structural walls, both regarding weight and stiffness, even in buildings where the number of non-structural walls is relatively small compared to structural walls.

System Identification of Tall Mass Timber Structures Employing Ambient Vibration Test and Fe Modelling

“…Details of the sensitivity analysis of the complex model is shown in Figure 12 for the complex model. The results agree well with the findings in [10,11] that indicates low sensitivity of the FE model developed in RFEM to the different assumptions of connection types in structural elements (fixed, pinned or hinged).…”

“…Having an experimental database of modal parameters, FE models with increased accuracy can be developed by engineers in practical design [10]. However, certain details of modelling such as connection types and material properties are still open issues in frequency calculations and overall dynamic behaviour of timber building.…”

“…Reynolds et al reported, for the two 5-storey buildings, that the FE modelling of just concrete core provided lower fundamental natural frequencies than the measured values [7]. Larsson et al investigated a nine-storey concretetimber hybrid building and found that dynamic properties were highly sensitive to the selected elastic properties of CLT walls, but insensitive to the connection properties [10]. Aloisio et al modelled eight-storey CLT student apartments building located in Norway.…”