SE 154 Timber Design Summer 2014 University of California San Diego Geoff

Se 154 timber design summer 2014 university of

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SE 154 Timber Design Summer 2014 University of California, San Diego Geoff Warcholik Department of Structural Engineering Page 12 of 23 SE154_SU14_Lecture #7 Wind Loads - Method 1 - Projected Area MWFRS (Main Wind Force Resisting System) p s = λ K Zt I p s30 min ±10-psf (vertical surface) C&C (Components & Cladding) p net = λ K Zt I p net30 min ±10-psf any element based on "effective wind area"
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SE 154 Timber Design Summer 2014 University of California, San Diego Geoff Warcholik Department of Structural Engineering Page 13 of 23 SE154_SU14_Lecture #7
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SE 154 Timber Design Summer 2014 University of California, San Diego Geoff Warcholik Department of Structural Engineering Page 14 of 23 SE154_SU14_Lecture #7
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SE 154 Timber Design Summer 2014 University of California, San Diego Geoff Warcholik Department of Structural Engineering Page 15 of 23 SE154_SU14_Lecture #7 Surface Roughness Categories : A ground surface roughness within each 45◦ sector shall be determined for a distance upwind of the site as defined in Section 6.5.6.3 from the categories defined in the following text, for the purpose of assigning an exposure category as defined in Section 6.5.6.3. Surface Roughness B : Urban and suburban areas, wooded areas, or other terrain with numerous closely spaced obstructions having the size of single-family dwellings or larger. Surface Roughness C : Open terrain with scattered obstructions having heights generally less than 30 ft (9.1 m). This category includes flat open country, grasslands, and all water surfaces in hurricane prone regions. Surface Roughness D : Flat, unobstructed areas and water surfaces outside hurricane prone regions. This category includes smooth mud flats, salt flats, and unbroken ice.
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SE 154 Timber Design Summer 2014 University of California, San Diego Geoff Warcholik Department of Structural Engineering Page 16 of 23 SE154_SU14_Lecture #7 Exposure Categories Exposure B : Exposure B shall apply where the ground surface roughness condition, as defined by Surface Roughness B, prevails in the upwind direction for a distance of at least 2,600 ft (792 m) or 20 times the height of the building, whichever is greater. EXCEPTION: For buildings whose mean roof height is less than or equal to 30 ft, the upwind distance may be reduced to 1,500 ft (457 m). Exposure C : Exposure C shall apply for all cases where Exposures B or D do not apply. Exposure D : Exposure D shall apply where the ground surface roughness, as defined by Surface Roughness D, prevails in the upwind direction for a distance greater than 5,000 ft (1,524 m) or 20 times the building height, whichever is greater. Exposure D shall extend into downwind areas of Surface Roughness B or C for a distance of 600 ft (200 m) or 20 times the height of the building, whichever is greater.
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SE 154 Timber Design Summer 2014 University of California, San Diego Geoff Warcholik Department of Structural Engineering
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  • Fall '08
  • staff
  • Structural Engineering, San Diego, Earthquake engineering, Structural load, Timber¬†Design, Geoff Warcholik

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