Dynamic Response of Tall Timber Buildings under Service Load – DynaTTB

In the project, measurement of dynamic properties of six full-scale buildings have been conducted using Forced Vibration Tests (FVT). In these tests, a shaker was placed in the buildings and a vibration force applied that simulate forces and movements of the same magnitude as expected by wind loading. The buildings have also been equipped with accelerometers at different levels. The data from these measurements have been used to evaluate resonance frequencies, mode shapes and damping. Using shakers with varying forces also make it possible to evaluate the amplitude dependency of the dynamic properties accurately. These data show that the damping of these relatively light buildings behaves non-linearly i.e., varies with amplitude in a way that it does not do for more heavy buildings. Measurement campaigns are planned for a few more buildings but were postponed due to travel restrictions within Europe.

Finite element models have also been created for all the buildings. These models, based on best engineering estimation, has in a first step be used for planning the measurement. In the next step these models have been, and will be further, improved for prediction of the real response of the buildings. The models are used to establish strategies for modelling full scale buildings in the serviceability limit stage. The models are also used for sensitivity analysis to learn which parameters are most important to model correctly to predict the dynamic properties. The studies show that it is important to include good data for stiffness of connections and reasonable values for masses. The effect of additional mass and stiffness of non-load bearing elements such as screeds, interior walls and facades are also important to include in the models in the serviceability limit stage. To complement the measurements and FE-models on full-scale buildings, effort is also done on modelling components and connections such as dowel connections in beam-column connections and diagonal-column connections as well as complete trusses.

The results will be summarized in a Tall Timber Buildings Design Guideline – Serviceability limit stage. The guideline will include chapters for each building as well as recommendations on how to measure dynamic properties of tall timber buildings and recommendations on how to create FE-models working in the serviceability limit stage. The data and calculation models will also be included in the design codes in the future to facilitate optimization of the design of Tall Timber Buildings.

The data and calculation models will also be included in the design codes in the future to facilitate optimization of the design of Tall Timber Buildings.

Main production : a TTB Design Guideline for design practitioners (book).
Several Journal and conference papers.

The Dynamic Response of Tall Timber Buildings under Service Load (Dyna-TTB) project is supported under the umbrella of ERA-NET Cofund ForestValue. Its aim is to quantify the structural damping in as-built tall timber buildings (TTB), identify and quantify the effects of connections and non-structural elements on the stiffness, damping and wind-induced dynamic response of TTBs, develop a bottom-up numerical finite element model for estimating the dynamic response of multi-storey timber buildings, validate the predicted response with in-situ measurements on TTBs and disseminate findings via a TTB Design Guideline for design practitioners.

The project aims for a comprehensive understanding of the dynamic response of tall timber buildings under serviceability loads. Full building numerical models’ response will be compared with the experimentally measured in-situ data. The overall chain of information will be traced down to the experimental response of the main building blocks – timber elements and steel connections. The currently missing or uncomplete data will be evaluated (i.e. damping parameters of different types of tall timber buildings) for different types of boundary conditions. The broad set of parameters evaluated at the end of the project will enable a more precise and rational design of tall timber buildings with a higher comfort for their occupants.
WP 1 – Coordination
The coordination work package is responsible for the administration of the project, including the consortium agreement, information, reports, and external representation of the project. The project coordinator is responsible for the internal project management and project meetings.
WP 2 – Laboratory-based experimental determination of dynamic response of components, connections and sub-assemblies
The objective of the work package is to experimentally study the dynamical properties for components connections and sub-assemblies for TTBs. The dynamical response will be studied using vibration and cyclic tests on different prototype scales: 1) single full-size timber components, 2) connection details and 3) sub-assemblies with more than two wooden members and non-structural material. The results from laboratory tests will be used to calibrate the numerical models.
WP 3 - In-situ measurements
A European-wide programme of short term FRF-based dynamic tests will be carried out on a number of representative buildings in Sweden, Norway, France and some other EU countries currently building TTB construction.
WP 4 - Numerical modelling of dynamic response
The objective of the work package is to experimentally study the dynamical properties for components connections and sub-assemblies for TTBs. The dynamical response will be studied using vibration and cyclic tests on different prototype scales: 1) single full-size timber components, 2) connection details and 3) sub-assemblies with more than two wooden members and non-structural material. The results from laboratory tests will be used to calibrate the numerical models.
WP 5 – Dissemination and Exploitation
Dissemination of research findings and impact within the timber-based construction industry, is a fundamental part of this project. The activities will ensure that the specific knowledge is transferred to the targeted industrial sector, informing states and municipalities of the latest findings, as well as raising awareness among the general public. Furthermore, the results obtained in this project will have the potential to be implemented in building design codes. For the intermediate period the Design Guidelines published at the end of the project will fill the knowledge gap.

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