ACI 318-05 Concrete Frame Design Manual

ACI 318-05 Concrete Frame Design Manual. Seismic Load Effects IBC 2006 requires that all structural element design resist earthquake motions in accordance with ASCE 7-05. ETABS allows users to activate Special seis- mic load effects using appropriate commands on the Define menu. The special seismic loads are computed in accordance with ASCE 7-05 sections 12.3.4 and 12.4. By default, the program uses the reliability factor, ρ, as 1.0 unless overwritten by the user. The reliability factor, ρ, and DL multiplier are automatically ap- plied to all program default design combinations when the ACI 318-05/IBC 2006 code is selected. The DL multiplier represents the 0.2S DS factor in Equa- tion 12.4-4 of ASCE 7-05. The program default value is 0.2. When seismic load E is combined with the effects of other loads, the following load combina- tion shall be used in lieu of the seismic load combinations in section 9.2.1 of ACI 318-05. Design of Joints This section is applicable to ETABS only. To ensure that the beam-column joint of special moment resisting frames pos- sesses adequate shear strength, the program performs a rational analysis of the beam-column panel zone to determine the shear forces that are generated in the joint. The program then checks this against design shear strength. Only joints that have a column below the joint are designed. The material prop- erties of the joint are assumed to be the same as those of the column below the joint. The joint analysis is performed in the major and the minor directions of the column. The joint design procedure involves the following steps:  Determine the panel zone design shear force  Determine the effective area of the joint P-Delta Effects The program design process requires that the analysis results include P-delta effects. The P-delta effects are considered differently for “braced” or “non-sway” and “unbraced” or “sway” components of moments in columns or frames. For the braced moments in columns, the effect of P-delta is limited to “individual member stability.” For unbraced components, “lateral drift effects” should be considered in addition to individual member stability effect. The program assumes that “braced” or “nonsway” moments are contributed from the “dead” or “live” loads, whereas, “unbraced” or “sway” moments are con- tributed from all other types of loads. For the individual member stability effects, the moments are magnified with moment magnification factors, as documented in Chapter 3 of this manual. For...