Wind Effects on Building Components & Cladding
1. A spreadsheet, "InternalExternalPtCp.xlsx", containing simultaneous internal and external pressure coefficient data, can be found on the OWL site. The file contains pressure data from a tap on the wall of a wind tunnel model, near an opening on the wall. Data from a pressure tap placed within the volume of the building is also included. Details on the experiments can be found in Ho et al. (2005) and Oh et al. (2007).
Using the pressure coefficient time histories along with a numerical model for the derivative terms, compute each of the four terms in the internal pressure equation on page 30 of the slide deck from "lecture 5 internal pressures and equalization.pdf". Using a statistical analysis of the data for the four terms, (i) compare the relative magnitudes of the terms and (ii) assess the accuracy of the internal pressure model compared to this particular data.
2. Determine the 50--yr return period, basic wind speeds (i.e., 10 m, 3--sec gusts in open terrain) for 11 mm thick, OSB roof sheathing panels on wood--frame houses using 63 mm twist shank nails, 63 mm "Hurriquake" nails, and 50 mm staples. The panels are used on houses and the fastener spacings are "6/12" (i.e., 150 mm on edge trusses and 300 mm on interior trusses) for the nails and "6/6" (i.e., 150 mm on all trusses) for the staples. Use ASCE 7--10 for the wind loads. Discuss your findings and comment on the regions of the US and the conditions where these fastener/panel combinations can be used. Clearly indicate all assumptions in your report.
Notes: (1) See the data from Henderson et al. (2013), Figure 6, for information on ultimate capacities. For the staples, use the "dynamic" load values. (2) In the ASCE 7--10 wind speed maps for Risk Category II (i.e., I = 1.0), the wind speed are for a 50--yr return period multiplied by the load factor, i.e., 50--yr wind speeds multiplied by 1.6.
3. Glass is known to fail due to pressure loads under a mechanism called static fatigue so that the magnitude and duration of loads are both important. For design, the pressure time history must be converted to an equivalent static pressure, peq, considered over a particular duration, tref. The time history and equivalent static values are related through the modified Brown's integral:
Peq(tref) = (∫0T Ps(t)dt/tref)1/s
In model-scale dimensions (i.e., do not convert the data to full--scale dimensions), determine the value of tref if peq is the single largest peak observed in the wall time series from the data in #1 above. Use s = 13.