MEMBER Wood Products;

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MEMBER Forest Operations; Pulp, Paper and Bioproducts;

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This report addresses serviceability issues of tall wood buildings focusing on their vibration and sound insulation performance. The sound insulation and vibration performance may not affect the building’s safety, but affects the occupants’ comfort and the proper operation of the buildings and the function of sensitive equipment, consequently the acceptance of the midrise and tall wood buildings in market place. Lack of data, knowledge and experience of sound and vibration performance of tall wood buildings is one of the issues related to design and construction of tall wood buildings. In order to bridge the gaps in the data, knowledge, and experience of sound and vibration performance of tall wood buildings, FPInnovations conducted a three-phase performance testing on the Brock Commons 18-storey wood-concrete building of 53 m tall at UBC campus. It was the tallest wood building in the world in 2017. The construction of the 18-storey building provided a unique opportunity for FPInnovations to conduct non-destructive testing on the tallest wood building in the world and on the unique CLT floor system. A three-phase testing was performed: 1) on June 22-23, 2016 during the construction to determine the vibration performance of the unique CLT floor system with point supports, 2) on January 17-18, 2017, when the building was nearly completed, to measure the building natural frequencies and damping ratios, and 3) on July 19-20, 2017, after the building was completed and ready for occupants to move in, to measure the sound insulation ratings of a CLT floor-ceiling assembly and a steel stud partition wall. Ambient vibration testing (AVT) was conducted on the building to determine its natural frequencies and damping ratios using the verified FPInnovations’ AVT protocol. Hammer impact testing was conducted on the selected innovative CLT floors to determine their fundamental natural frequencies and damping ratios. Static deflection testing was performed on the floors to measure their deflections under 1-kN point static load. The floor vibration performance tests used ISO floor vibration test methods. Informal subjective evaluations were also conducted on the floors to assess the floor vibration performance. ASTM standard field test methods for building sound insulation were used to determine the apparent sound transmission class (ASTC) and the apparent impact insulation class (AIIC) of the selected CLT floor-ceiling assembly, and the ASTC of the selected steel stud partition wall. The measured frequencies of the first three vibration modes were 1.0 Hz (1.0 second period) for the translational vibration in the building short-axis, 1.2 Hz (0.8 second period) for the torsion and 4.0 Hz (0.25 second period) for the translational vibration in the building long-axis. The damping ratios for these three modes were 1% of the critical damping. The measured fundamental natural frequency of the CLT floor was 18.3 Hz and the 1kN static deflection was 0.15 mm. The floor design was conservative in comparison with the vibration controlled CLT spans determined using CSA O86 method. The vibration performance was highly satisfied to the evaluators. The measured ASTC and AIIC of the selected CLT floor-ceiling assembly were 55 and 53, respectively. The measured ASTC of the steel stud partition wall was 53. In general, the quality of the results indicated that the approaches, methods and equipment selected for use for the tests were reasonable for meeting the objectives of this project. The CLT floor vibration performance is deemed to be satisfactory. The sound insulation performance of the tested CLT floor-ceiling assembly and steel stud wall is beyond the code requirement and recommendation. It is recommended to compare the building frequencies estimated by the design tool or model with the measured values, to seek out the reasons why if the discrepancies are significant, and to decide if and how the models and assumptions should be refined. The measured and estimated values should also be correlated with actual experiences of the occupants in the building if such information is obtained, for example, through a survey.


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  • Wood products member
  • Pulp, paper and bioproducts member
  • Forest operations member