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*SEFP Consistent Design* *1997 UBC vertical earthquake term* *Doc No: 10-00-CD-0002* *Date: May 30, 2013* *Article is ripped: Good one to share though* For Strength Design, Ev has the effect of increasing compression and tension/uplift effects on vertical load carrying systems. Ev is not applicable for Allowable Stress Design. The new term, Ev, was introduced in the 1997 UBC. UBC Section 1630.1 defines Ev as the load effect resulting from the vertical component of the earthquake ground motion. For Strength Design, Ev is defined as 0.5CaID. For Allowable Stress Design, Ev is defined as 0. Ca= seismic coefficient from UBC Table 16-Q I = importance factor from UBC Table 16-K D = dead load UBC Section 1630.1.1 defines the earthquake load, E, as the earthquake load on an element of the structure resulting from the combination of the horizontal component Eh and the vertical component Ev. E = Rh*Eh + Ev (UBC 30-1)Rh= redundancy factor defined in UBC Section 1630.1.1Eh = earthquake load resulting from either the base shear, V, or the design lateral force, FpSubstituting the definition of Ev into this equation results in:E =Rh*Eh + 0.5CaID (Modified 30-1)The 1997 UBC defines load combinations in Section 1612. Strength load combinations 12-5 and 12-6include E.1.2D + 1.0E +(f1L + f2S) (UBC 12-5)0.9D (1.0E or 1.3W) (UBC 12-6)Substituting modified equation 30-1 into these equations results in:1.2D + 1.0 Eh + 0.5CaID + (f1L + f2S) (Modified 12-5)(0.9 + 0.5CaI)D + Eh (Modified 12-6a)(0.9 - 0.5CaI)D - Eh (Modified 12-6b) All terms with Eh are effects of horizontal earthquake components. These loads can be in any direction, for example, vertical loads on rigid frame columns, horizontal loads on columns, and diagonal loads on braced frames. Similarly, all terms with D, L, or S are effects of vertical loads or components. These loads can be in any direction, for example, vertical loads on beams, horizontal loads on rigid frame columns, and diagonal loads on braced frames. Example:For typical California values of Ca = 0.40 and I = 1, the modified equations become:1.4D + 1.0Rh*Eh + (f1L + f2S)1.1D + Rh*Eh0.7D + Rh*Eh The impact of the vertical earthquake component on modified Strength Design equations 12-5 and 12-6a is to increase compression effects on columns and foundations. The impact of the vertical earthquake component on modified Strength Design equations 12-6b is to increase tension and uplift effects on columns, anchorage, and foundations. There is no impact of the vertical earthquake component on Allowable Stress Design load combination equations.