10179420_305 E. 4TH - Plan (2) - Laserfiche WebLink

Home Browse Search

C. METHOD OF ANALYSIS (CONT.) The basic wind speed of 70 mph used in our analysis is based on a probability of 0.20, or a recurrence interval of 5 years. This basic wind speed results in wind pressures that are reasonable for a temporary structure which is to be disassembled immediately after each event. It should be mentioned that there is an additional factor of safety in our wind load analysis, since the roof top covering is designed to detach itself from the structure prior to developing the wind pressures that would result from 70 mph wind loads. Due to the larger exposed area presented by the front of the roof top, the critical wind loads results are obtained for the wind direction parallel to the ridge case. Load Combinations The Roof Top structure was analyzed for the following load combinations: - Load Combination 1: SW + RTC +R+O - Load Combination 2: SW+RTC-WL+1/20 - Load Combination 3: SW + RTC-WL (Gravity Effects) (Stability Effects) (Stability Effects) 7-Load Cdr=nbination 1 will-give-the maximum stress results in the roof top and tower members for all gravity loads..· Load Combinations.2 and -3 will. provide..us, with the requirements for providing hold-down stability for the roof top structure. The. maxirrium forces in the guys as well -as the forces that must be resisted by the ground anchors at each guy location will be reported. Finally, the ballast required at each tower base location for uplift stability will be provided. Since wind uplift and overturning stability are dependent on the magnitude of the gravity load on the roof top structures, two load combinations were investigated for the stability case. Load Combination 2 considers that the roof top would be loaded with one-half of the operating load during a maximum wind load event, and Load Combination 3 .con;iders..that· the structure self weight and weight of thecanvas would be the only resisting gravity loads. - - 8