Performance-based wind assessment of tall self-centering mass-timber buildings under simulated downburst winds

The lightweight and low lateral stiffness of engineered wood products make the structural design of tall mass-timber buildings wind-critical. Performance-based wind design (PBWD) provides a framework for optimizing design by allowing nonlinear deformation in wind-force-resisting systems. Downburst winds are nonstationary and exhibit a distinct vertical profile, often characterized by maximum wind speeds below 100 m, comparable to the heights of tall mass-timber buildings and potentially exceeding synoptic design demands. Hence, performance-based wind assessment (PBWA) of such buildings under downburst wind loads is crucial. This study presents PBWA of 11-, 17-, and 22-story mass-timber buildings with post-tensioned cross-laminated timber (PT-CLT) rocking walls under simulated downburst wind loads. The buildings were initially designed for synoptic wind loads using a PBWD framework. Downburst wind loads were developed from historical thunderstorm data and a deterministic-stochastic hybrid simulation approach. Structural responses were evaluated through nonlinear dynamic analyses using 100 randomly generated downburst wind time histories. The performance of deformation-controlled components in PT-CLT walls, i.e., U-shaped flexural plates, was further assessed through experimental tests under a newly developed quasi-static downburst-like wind-loading protocol. Both numerical and experimental results show that the prototype buildings designed using PBWD for synoptic winds can withstand downburst loads with equivalent recurrence probabilities. • PBWD-designed tall self-centering mass-timber buildings are evaluated under simulated downburst wind loads. • Existing ASCE/SEI PBWD component-level criteria are inadequate for short-duration downburst winds. • A downburst-like quasi-static loading protocol based on nonlinear UFP response histories is developed. • Experiments under a downburst-like loading protocol establish new performance criteria for UFPs.