Results from a series of blast tests performed in October 2016 on three two-story, single-bay cross-laminated timber (CLT) structures demonstrated the ability of CLT construction to resist airblast loads in a predictable fashion. These tests were performed on structures without superimposed load to limit inertial resistance. Subsequently, a follow-on series of tests was performed to investigate the response of axially-loaded CLT construction. Panels damaged during the preceding test were removed and replaced. Axial load was applied using precast concrete blocks to simulate the loaded condition of a five-story building at the first-floor front panel of the structures. These test structures were exposed to two shots: the first was designed to keep the structures within their respective elastic ranges while the second was designed to push the structures beyond their elastic limits. Reflected pressure and peak deflections were recorded at the front panels of the test structures to document the two-way panel load distribution behavior under a dynamic load event and the clearing of the shock wave. Prior to conducting the blast tests, a small number of tests were performed on a load tree test apparatus to aid in test planning by investigating the post-peak response of individual CLT panels of various lengths to quasi-static out-of-plane and axial loads applied simultaneously. This paper provides an overview of the results obtained from both the quasi-static and blast tests of axially-loaded CLT. Additionally, the paper compares CLT structure, component, and connection response across the suite of data. Conclusions are offered to assist engineers in the design of load bearing CLT construction exposed to airblast loads.
April 3-5, 2014, Boston, Massachusetts, United States
The goal of this research was to develop a structural system for tall buildings using mass-timber as the main structural material that reduces the carbon dioxide emissions associated with the structure. The structural system research was applied to a prototypical building based on an existing concrete benchmark for comparison.
This paper discusses key design issues associated with tall mass-timber buildings along with potential solutions. It is believed that the system proposed in the research and discussed in the paper could mitigate many of these design issues. The main structural mass-timber elements are connected by steel reinforcing through cast-in-place concrete at the connection joints. This system plays to the strengths of both materials and allows the designer to apply sound tall building engineering fundamentals. The result is believed to be an efficient structure that could compete with reinforced concrete and structural steel while reducing the associated carbon emissions by 60 to 75%.