Project: Research at Pilgatan, Varberg
In the locality of Trönninge, near Varberg on the Swedish West coast, Derome is developing a new residential area. Two six-storey apartment buildings, constructed in 2020-21, serve as research objects. Firstly, one of the buildings is equipped with about 120 sensors that record temperature and humidity; secondly, the dynamic performance of both buildings is measured and evaluated.
Project information
Project manager
Michael Dorn
Other project members
Carmen Amaddeo
Participating organisations
Linnaeus University, Derome
Financier
The Nils and Dorthi Troëdsson Research Foundation, The Knowledge Foundation
Timetable
2020-09-01 – ongoing
Subjects
Building technology (Department of Building Technology, Faculty of Technology)
Research groups
Structural Condition Monitoring (within the field of building technology)
Linnaeus Knowledge Environment
Green Sustainable Development
More about the project
General
The studied buildings are two six-story appartement buildings in Varberg on the Swedish west coast. The buildings are constructed using light-weight elements, prefabricated at the factory, and put together on the building site. The buildings are very much identical to each other since they are located next to each other, they are orientated in the same direction, have the same construction type etc. The buildings were built after each other, House B was erected between September 2020 until May 2021, a few months after House A.
Long-term monitoring
In house B, a permanent monitoring system was deployed during construction. At eight locations at the concrete bottom plate, at eight locations in the outer walls as well as at two positions in the roof, groups of combined temperature and rel. humidity sensors were installed. In addition, a weather station is located close by to obtain local environmental information.
Sensor placement started in autumn 2020 at the bottom plate and continuously throughout the building process in the walls and in the roof at last. Also, measurement started already during the construction phase so that this important part is already partly logged. The whole system is running since March 2021, the apartments were rented out with June 2021.
In total, about 120 sensors have been placed and send data in 5-minute intervals. Currently, automated visualization and evaluation routines are developed. The objective is to learn more about the moisture state at those locations and the functionality of the buildings system. The different locations can be compared to each other, e.g., for differences in West- or East-facing facades or checking for differences between floor 1 or floor 6.
Dynamic properties of multi-stores timber buildings
Timber is a construction material which changes its properties depending on the environment, e.g., seasonal changes in humidity and temperature. Affected properties are stiffness, strength, density and dimensional stability on material level. Additionally, on system level, some variations are observed, e.g., at connections.
A recently developed data acquisition system for dynamic measurement is used in the study. The system uses multiple acquisition units which are time synchronized to get good time stamping. Thereafter, each unit is placed at the correct position within the building in different floors and connected to accelerometers. Ambient vibrations, e.g. from wind loads, are sufficient to obtain good data during about 1-2 hours of measurement time. The wireless system simplifies setup while it at the same time minimizes disturbances to the users.
The dynamic properties are extracted from the acceleration data by Operational Modal Analysis (OMA) in the post processing. OMA allows to obtain the eigenmodes, the shapes of the eigenmodes as well as the corresponding eigenfrequencies. The study also includes a comparison of the measured properties with results from structural models of the buildings. The structural model is a three-dimensional representation of the buildings, its properties and loading conditions. For light-weight timber buildings such as these, the creation of the structural models is very challenging as the buildings consists of many elements and a very high number of connections.
Starting in May 2024, a permanent dynamic system was added which measures at two positions in the roof. Hereby, the dynamic properties are registered with much better time-resolution. These long-time measurements are a good addition to the earlier dynamic measurements and will in the future be combined with the measurements from the walls.
The project is part of the research in the Structural Health Monitorering research group within the field of building technology and is included in the Linnaeus University Knowledge Environment: Green Sustainable Development