CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING



AbstractLow-rise wood buildings occupy over 95% of all residential structures in the US. However, low-rise buildings usually perform poorly during extreme wind events, such as hurricanes and tornadoes. To ensure the resilience of low-rise buildings to various loads, codes, specifications, and design manuals are usually adopted. However, wind loading in these design codes is typically represented by simplified wind pressure coefficients. Both the directional and envelope methods provided in the current standard consider explicitly the wind directions normal and parallel to the ridge of buildings, with the other directions enveloped for generalization purposes. In comparison, the database-assisted design (DAD) method, which has received increased attention from researchers, is characterized by the direct use of pressure time series from a large number of pressure taps measured in wind tunnel tests for various wind directions. Based on the several previous versions of the current standard, many researchers compared the wind pressures and peak responses from the DAD method and the directional and envelope methods in the current standard. Both methods were found to provide underestimated results. Currently, in addition to the absence of comparisons for the current standard, comparisons of the DAD method with the time-history analysis using the directional and envelope methods for a full-size building considering the material nonlinearity have not been performed. Moreover, the effects of wind speed and wind direction on the wind pressures and peak responses of structures have been ignored. In this paper, the results from both directional and envelope methods with time history analysis for low-rise residential buildings are assessed and compared with those from the DAD method. Synthetic hurricane tracks were incorporated based on the real wind speeds and directions in the community. Transient analysis with the time histories of wind pressures were applied to a realistic full-scale building model under different wind speeds and wind directions. The results suggest that the directional and envelope methods lead to an underestimated displacement, especially at high wind speeds. With wind directions parallel and normal to the ridge of buildings explicitly considered in the current standard, critical wind directions other than the two directions could not be detected, which could underestimate wind-induced responses.



Source link

Leave a Reply

Your email address will not be published. Required fields are marked *