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7 of 234 5.5.2.3 6.2 7.2 Specific checks pertaining to Concrete moment frames: No Shear Failures - per C5.5.2.3.4, members that cannot develop the flexural capacity in shear shall be checked for adequacy against calculated shear demands. For columns, the shear capacity is dependent upon the level Concrete Moment Frame Checks of axial stress and therefore will be evaluated for all pettinent load combinations to determine the most cntical. Bar splices - not considered critical as 50%/50yr axial-flexural demand/capadty is typically well below 1 0 and likely bar splice locations at Levels 3 up are at the elevations of infill r,anels 'mnt:irinrl' cnlijmns a low flexural demand lor.ation In the absence of structural drawings or spedfications, data is based on results of on-site investigations induding targeted destructive and nondestructive testing of building materials and components Architectural drawings show key member profiles consistent with field measurements. The field testing program indudes an overall visual condition survey, strength testing small-diameter concrete cores extracted from columns and beams, Ground Penetrating Data Collection Requirements Radar (GPR) scans of concrete faces for rebar below the surface, and hardness tests of exposec rebar to establish the proper grades. Considering the regular pattern of the perimeter moment frame and the main focus on evaluating lower level framing members, we consider the concrete tests and GPR scans at multiple column lines on multiple floors achieve a 'Comprehensive' Level of Knowledge. We apply the associated knowledge factor, kappa, of 1.0 This is in line with the provision of 6.2 2 point #2. Nonlinear Response History Analysis is the principal approach, with Linear Response Spectrum General Analysis Requirements Analysis (RSA) modified for assumed total damping per 7.2.3.6 as another form of validation 7.2.3.2 Torsion The lateral system surrounds the tower, so shifting the center of mass in the computer models to account for accidentally eccentricity will not significantly affect member demands. For one sampl set of acceleration history records, demands change approximately 5%, in line with expectations In addition, for members acting below yield at 72yr MRI accidental eccentridty from unevenly distributed seismic damage is not an issue. For these reasons accidental eccentricity is not built into every computer run. Table 7-1 Required Number of Ground Motions When using 3 ground motions for a Limited Performance Objective structure, the maximum values denved from the set shall be used. We run 4 ground motions and still use the maximum values found. The capacity of force controlled members such as columns under axial load is the product of kappa and the lower-bound strength. The lower-bound strength, Qd, is defined as the meanCalculation of Component Action minus one standard deviation of the tested concrete compressive strength. For rebar, nominalTable 7-7 Capacity Nonlinear Procedures yield value for the grade indicated by Brinell hardness testing is used since the grade is already determined conservatively Field testing of concrete compressive strength and steel reinforcement yield and ultimate Concrete Material Proprerties strengths for grades indicated by field hardness testing of rebar exposed by chipping. Bar samplf extraction for tension testing is not planned as nominal steel grades are conservatively applied. 1022.1 10.2.2.2 Concrete Component Properties Several site walks were conducted to address the points listed. The coefficient of vanation for field test results concerning concrete compressive tests is well below 20% Concrete test frequency, column/beam GPR scanning frequency, and visual 10.22.4.2 Comprehensive Data Collection condition survey extent are consistent with a comprehensive collection program for the perimeter moment frames. Table 10-5 Effective Stiffness Values Column Flexural Rigidity is directly proportional to the level of design gravity loads sustained. Fot perimeter mpment frame columns, this was found to be beneath the 0.1Agfc threshold in nearly all instances. Therefore, a 0.3Eclg stiffness modifier is applied to the analysis model. Although nonprestressed beams are permitted to use the same 0.3Eclg modifier, the design team recognizes that the deep beam/infill panel assembly is unlikely to experience that level of crackin so a 0 7Eclg factor is applied to beams. The resulting periods for the lowest modes are similar to the default upper limit on period in ASCE 41, supporting this approach. 103.2.3 Force-Controlled Actions Procedures outlined in ASCE41-13 and ACI 318 are permitted to calculate member design strengths except that the strength reduction factor, 0, shall equal 1.0. Fig. 10-2 Beam-Column Joint Modeling Isolated partial-elevation analysis models wth detailed finite elements of beams and infill panels are used to establish the locations, percentages and lengths of rigid offsets at single-line momen frame beams in the main model for equivalent lateral stiffness Behavior is bracketed by indudin column capture above the floor in most models, the 'default' condition, and minimizing it in other models. Because reduced column capture effects lengthen modal penods, the influence on demands is relatively minor. 10.3.4 Shear and Torsion "Where the longitudinal spadng of transverse reinforcement exceeds half the componenet effective depth measured in the direction of shear, transverse reinforcement shall be assumed n( more than 50% effective in resisting shear or torsion." Spacing of column ties was found to be between d/2 and d, where d is the effective depth measured in the direction of shear. This minor shear resistance contribution is included in calculations. 10.4.2.3 Strength of Moment Frames Column shear strength is a function of the axial, shear, and moment demands under a given loac combination The most critical permutation, typically assuming the smallest column compression value found, is being used to establish the governing concrete column shear capacities. The degree of conservatism in this approach is being studied separately, based on the probability of maximum shear and minimum axial compression occurnng simultaneously.