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CEE 9524A Wind Effects on Building Components and Cladding

Assignments 2

The objective of this assignment is to take wind tunnel pressure data and develop ASCE-­‐7-­‐equivalent external pressure coefficients, and then to compare the results with those in ASCE 7-­‐10. The steps to achieve this, and the data to be used, are described below.

Two spreadsheets are relevant for this assignment: “RoofCornerCpTTU.xlsx” and

“WindSpeedProfile.xlsx”. The first contains pressure data from the roof of a wind tunnel model replicating the TTU-­‐WERFL building at a scale of 1/50. This building has an eave height of 13 ft and a gable roof slope of 1/48, which can be considered as flat. Time histories of pressure coefficients for 16 taps located near the corner of the roof are included for each of 3 wind directions, viz., 0o, 45o and 90o. The time history data for each pressure tap are provided as a column of data in the sheets, so there are 16 columns in each sheet. The tap numbers and tap locations are provided on another sheet within the file and are given in full-­‐scale dimensions. The pressure coefficients are referenced to the mean wind speed at the roof height. The second file provides the mean wind speed and turbulence intensities, with the elevation, z, given in full-­‐scale dimensions.

Steps:

1. We won’t look at all possible areas with this array of Rather, we will look at a subset of them. In particular, consider the following three areas: (i) 16 taps individually, (ii) 4 square areas made up of the (non-­‐overlapping) sets of 2 x 2 taps and (iii) 1 area made up of all 16 taps (4 x 4 taps). Determine the time histories of the area-­‐averaged pressure coefficients.
2. Divide the resulting time histories into 10 equal segments and identify the median peak value for each area and for each wind Identify the locations of the worst-­‐case values and wind directions.
3. Convert the peak, area-­‐averaged, pressure coefficients into ASCE 7 GCp values, e., a reference velocity of 3-­‐sec gust speed at 10m. Make sure to carefully describe your velocity conversion assumptions. Plot your resulting peak values (all of them) versus area, using the format of ASCE 7-­‐10 (i.e., GCp versus log of area). Draw a curve on the plot that would represent your choice for the code based on this data.
4. Discuss how your results of this TTU-­‐WERFL building compare to those in ASCE 7-­‐10. Comment on the how uncertainties and assumptions in your analysis may affect the