Project Specific Testing for Point Supported CLT

Design methodologies for one-way spanning CLT are proven and code prescribed. For two-way spanning CLT, as in a point-supported system, this is not the case, yet. There has been research and testing done in Europe and Canada, but the U.S. is working to catch up so that these systems can be widely accepted and approved by AHJ’s without any additional requirements. For a recent 12-story, Type IV-B, point-supported building in Portland, Oregon, we were required to go through project specific testing following IBC Section 1709 for pre-construction load testing as part of our permit approval process.

This presentation will cover the test program and specifics related to IBC Section 1709 as well as share results from the test. We will also discuss how we approached translating the test data to validate our design and presenting that to the AHJ for approval purposes.

Robin Landis

Senior Engineer
Holmes

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Mass Timber Acoustics R&D: Investigating Sound Transmission Through Continuous CLT Panels Without Ceilings

In this presentation, we will briefly discuss the concept of indirect (flanking) sound transmission in mass timber buildings, including through continuous ceiling CLT panels, and the impact on ASTC/NNIC performance. To this effect, attendees will gain insight to the junction vibration reduction index (Kij) and the importance of junction details in addressing flanking.

We will then shift the focus to a significant R&D endeavour undertaken to better understand flanking through continuous CLT panels, including discussion of previous test results, as well as a presentation of an HGC-Woodworks partnership to measure the effects on flanking of various different variables, such as type of floor topping above the CLT panels, isolation thickness, and wall connection detailing.

Simon Edwards

Senior Acoustic Engineer, Associate
HGC Noise Vibration Acoustics

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My Building is Making Noise! Common Post-Occupancy Characteristics of Mass Timber

Mass timber, like all materials, undergoes changes over time. This is particularly true in the first year of its installation as it adapts to environmental conditions and building occupation. As they begin using a mass timber building, your clients may notice occasional popping noises, fine cracks, or — in rare circumstances — small wood flakes detaching. While these occurrences may initially raise concerns, they are normal as wood acclimates to its role as a building structure.

This presentation will provide insight into mass timber for anyone preparing their client to occupy a mass timber structure. Understanding the multifaceted characteristics of mass timber construction enhances the appreciation and enjoyment of occupants living and working within these extraordinary spaces.

Scott Barton-Smith

Associate Principal
Bora Architecture & Interiors

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CLT Floor Vibration Across Construction Stages: A Comparative Study Using Field Measurements and Finite Element Models

Despite growing popularity, mass timber is adopted in few laboratory facilities partly due to vibration concerns. The current lack of vibration test data for cross-laminated timber (CLT) floors in real-world scenarios further limits its application. Most existing studies feature simplified environments, omitting critical factors such as the location of bays within the building, partitions, MEP systems, and cladding.

This presentation covers an experimental-analytical study of footfall-induced vibrations in a new mass timber classroom and office building, the Undergraduate Academic Building at UC Berkeley. Measurements were taken at various construction stages to assess the influence of different components on floor vibration performance. These stages included: bare CLT without topping or cladding; bare CLT after cladding installation; CLT with gypcrete and concrete topping with cladding installed; and CLT with topping, cladding, and partitions.

Measurements were compared with analytical predictions per AISC Design Guide 11, and the WoodWorks Mass Timber Floor Vibration Design Guide. Results were analyzed to examine the impacts of different components, the accuracy of current analytical methodologies, and cost-effective strategies for reducing vibrations in mass timber buildings. By examining vibration performance in conventional mass timber facilities, this study hopes to improve the feasibility of mass timber for future vibration-sensitive structures.

Zeyang Arthur Cao

Senior Engineer
Forell | Elsesser Structural Engineers

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Delegated Design for Mass Timber Projects

Delegated design allows the mass timber supplier to optimize the design for their capabilities and preferences, resulting in a more efficient, cost-effective, and constructible building. This session will discuss strategies for delegated design on mass timber projects, both for mass timber connections and for the full mass timber structure. While many structural engineers are accustomed to delegating connection designs for steel projects, successful delegated design for mass timber requires a different approach.

This presentation will define the roles of the key players on a delegated design project, help design teams understand how to clearly document the required information, and give real-world examples of “do’s and don’ts” for delegated mass timber design.

Tanya Luthi

Director of Engineering
Timberlab

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