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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.

SAP Import Export Problem SAP Import and Export $2k File Today I faced a very strange problem in CSI SAP. Have you ever faced such a problem in your structural analysis tools? Same model file was used which yielded different results under following 2 scenarios:- 1) 1-The original file was run in SAP. 2) 2- Then this file was exported in text format and imported again. Value of TIME PERIOD of both the models were different and we found out that there is about 300kN difference in Self Weight of elements. I examined both the text files in MS WORD Compare Document feature and found out that a beam having depth of 700mm has been added in new model (model based on importing the text file) on various locations other than the original one. While in the model when I showed selection only for this 700deep concrete beam I found it to be everywhere in the model. I will explain the solution of the problem in next lines. Actually the original model exported from ETABS to SAP so I cannot confirm whether all this discussion holds good too for the models originally created in SAP or not? Actually there were some NULL lines (created originally in ETABS) in the model. When you export the model as a text file and import it back it does not recognize the NULL lines but rather it applies those elements the first available section which in my case was 700mm deep concrete beam. So that’s why I got 300kN more self weight in the model due to these beams. So next time you export your model to SAP and send its text file for review to another person or firm, be informed that it will give them wrong results. So always send them SDB file.