- 2 5 Deliverable Determine The Effective Seismic Weight I E The Mass Source Per Asce 7 16 12 7 2 And Your Results Fr 1 (12.25 KiB) Viewed 61 times
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2.6 2.7 2.8 DELIVERABLE: Determine Seismic Base Shears, Vx and Vy, per ASCE 7-16 12.8. Define every parameter use to determine them. Obtain the Response Modification Factors, R, for x- and y-directions from Table 12.2-1. The seismic LFRS's in x- and y-directions for this warehouse are both "concentric braced frames with tension only braces" (i.e., ORDINARY CONCENTRIC BRACED FRAMES). Identify V and V, as LOAD PATTERNS 04_SX and 05_SY DELIVERABLE: Apply the Seismic Base Shears, V and Vy, obtained in 02.6 as lateral loads to the center of mass of WH03's roof. Present your results in a diagram of the warehouses or of its truss diaphragms for the x- and y- directions. Provide one diagram for seismic LOAD CASE in positive x-direction and one for seismic LOAD CASE in positive y-direction, Sx and Sy. Name this LOAD CASES 04_SX and 05_SY DELIVERABLE: ASCE 7-16 12.8.4.2 recognizes that dead and live loads have a probabilistic nature; thus, mass/load symmetry is not possible and displaces the location of the center of mass. Per ASCE 7-16 12.8.4.2, obtain two more LOAD CASES for seismic loads in the x and y directions that consider the required shifts for the location of the center of mass. Provide 2 additional diagrams (LOAD CASES 04_SX+ECC and 04_SX-ECC) for the positive x-direction (Steccentricity and Seccentricity) and 2 additional diagrams (LOAD CASES 05_SY+ECC and -eccentricity) 05_SY-ECC) for the positive y-direction (Seccentricity and Sy
12.7.2 Effective Seismic Weight. The effective seismic weight, W, of a structure shall include the dead load, as defined in Section 3.1, above the base and other loads above the base as listed below: 1. In areas used for storage, a minimum of 25% of the floor live load shall be included. EXCEPTIONS: a. Where the inclusion of storage loads adds no more than 5% to the effective seismic weight at that level, it need not be included in the effective seismic weight. b. Floor live load in public garages and open parking structures need not be included. 2. Where provision for partitions is required by Section 4.3.2 in the floor load design, the actual partition weight or a minimum weight of 10 psf (0.48 kN/m²) of floor area, whichever is greater. 3. Total operating weight of permanent equipment. 4. Where the flat roof snow load, Pf, exceeds 30 psf (1.44 kN/m²), 20% of the uniform design snow load, regardless of actual roof slope. 5. Weight of landscaping and other materials at roof gardens and similar areas.
12.8 EQUIVALENT LATERAL FORCE (ELF) PROCEDURE 12.8.1 Seismic Base Shear. The seismic base shear, V, in a given direction shall be determined in accordance with the following equation: V = C,W (12.8-1) where C, the seismic response coefficient determined in accordance with Section 12.8.1.1, and W = the effective seismic weight per Section 12.7.2.
ន S Seismic Force-Resisting System Table 12.2-1 (Continued) Design Coefficients and Factors for Seismic Force-Resisting Systems 5. Steel and concrete composite special concentrically braced frames 6. Steel and concrete composite ordinary braced frames 7. Steel and concrete composite ordinary shear walls 8. Ordinary reinforced concrete shear walls F. SHEAR WALL-FRAME INTERACTIVE SYSTEM WITH ORDINARY REINFORCED CONCRETE MOMENT FRAMES AND ORDINARY REINFORCED CONCRETE SHEAR WALLS G. CANTILEVERED COLUMN SYSTEMS DETAILED TO CONFORM TO THE REQUIREMENTS FOR: 1. Steel special cantilever column systems 2. Steel ordinary cantilever column systems 3. Special reinforced concrete moment frames™ 4. Intermediate reinforced concrete moment frames 5. Ordinary reinforced concrete moment frames 6. Timber frames H. STEEL SYSTEMS NOT SPECIFICALLY DETAILED FOR SEISMIC RESISTANCE, EXCLUDING CANTILEVER COLUMN SYSTEMS ASCE 7 Section Where Detailing Requirements Are Specified 14.3 14.3 14.3 14.2 12.2.5.8 and 14.2 12.2.5.2 14.1 14.1 12.2.5.5 and 14.2 14.2 14.2 14.5 14.1 Response Modification Coefficient, Rº 5½ 3½ 5 5½ 4½ 2½ 11 2½ 1½ 1 1½ 3 Overstrength Factor, 2½ 2½ 3 2½ 2½ 1¼ 1½ 1¼ 1¼ 1½ 3 Deflection Amplification Factor, Ca 4½ 3 4½ 4½ 4 "NL = Not Limited, and NP = Not Permitted. For metric units, use 30.5 m for 100 ft and use 48.8 m for 160 ft. "See Section 12.2.5.4 for a description of seismic force-resisting systems limited to buildings with a structural height, h, of 240 ft (73.2 m) or less. See Section 12.2.5.4 for seismic force-resisting systems limited to buildings with a structural height, h,,, of 160 ft (48.8 m) or less. "In Section 2.3 of ACI 318. A shear wall is defined as a structural wall. 2½ 1¼ 2½ 1½ 1 1½ 3 Structural System Limitations Including Structural Height, h, (ft) Limits NL NL NL NL 35 35 35 35 35 35 Seismic Design Category NL NP NL NL NL NL NL NP NP 35 35 35 35 NP 35 NL 35 NP 35 NP 160 100 NP NP NP NP NP 35 NP "Response modification coefficient, R, for use throughout the standard. Note that R reduces forces to a strength level, not an allowable stress level. Where the tabulated value of the overstrength factor, 2. is greater than or equal to 2½2, 22, is permitted to be reduced by subtracting the value of 1/2 for structures with flexible diaphragms. Deflection amplification factor, C, for use in Sections 12.8.6, 12.8.7, and 12.9.1.2. 22 2 F NP 2222 2 NP NP NP NP 35 NP NP NP NP NP NP NP 35 35 弓弓弓弓出层出 NP NP "In Section 2.3 of ACI 318. The definition of "special structural wall" includes precast and cast-in-place construction. 'An increase in structural height, h, to 45 ft (13.7 m) is permitted for single-story storage warehouse facilities. Steel ordinary concentrically braced frames are permitted in single-story buildings up to a structural height, h,,, of 60 ft (18.3 m) where the dead load of the roof does not exceed 20 lb/ft² (0.96 kN/m²) and in penthouse structures. See Section 12.2.5.7 for limitations in structures assigned to Seismic Design Categories D, E, or F. See Section 12.2.5.6 for limitations in structures assigned to Seismic Design Categories D, E, or F. "In Section 2.3 of ACI 318. The definition of "special moment frame" includes precast and cast-in-place construction. "Cold-formed steel-special bolted moment frames shall be limited to one story in height in accordance with ANSI/AISI $400. "Alternately, the seismic load effect including overstrength, Eh, is permitted to be based on the expected strength determined in accordance with ANSI/AISI $400. "Ordinary moment frame is permitted to be used in lieu of intermediate moment frame for Seismic Design Categories B or C. ET (powered by Edaptive Technologies) - Guest User 01 - 04/30/2018
Type 1a. 1b. 2. 3. 5. Table 12.3-1 Horizontal Structural Irregularities Description Torsional Irregularity: Torsional irregularity is defined to exist where the maximum story drift, computed including accidental torsion with A, = 1.0, at one end of the structure transverse to an axis is more than 1.2 times the average of the story drifts at the two ends of the structure. Torsional irregularity requirements in the reference sections apply only to structures in which the diaphragms are rigid or semirigid. Extreme Torsional Irregularity: Extreme torsional irregularity is defined to exist where the maximum story drift, computed including accidental torsion with A, = 1.0, at one end of the structure transverse to an axis is more than 1.4 times the average of the story drifts at the two ends of the structure. Extreme torsional irregularity requirements in the reference sections apply only to structures in which the diaphragms are rigid or semirigid. Reentrant Corner Irregularity: Reentrant corner irregularity is defined to exist where both plan projections of the structure beyond a reentrant corner are greater than 15% of the plan dimension of the structure in the given direction. Diaphragm Discontinuity Irregularity: Diaphragm discontinuity irregularity is defined to exist where there is a diaphragm with an abrupt discontinuity or variation in stiffness, including one that has a cutout or open area greater than 50% of the gross enclosed diaphragm area, or a change in effective diaphragm stiffness of more than 50% from one story to the next. Out-of-Plane Offset Irregularity: Out-of-plane offset irregularity is defined to exist where there is a discontinuity in a lateral force-resistance path, such as an out-of-plane offset of at least one of the vertical elements. Nonparallel System Irregularity: Nonparallel system irregularity is defined to exist where vertical lateral force-resisting elements are not parallel to the major orthogonal axes of the seismic force-resisting system. Reference Section 12.3.3.4 12.7.3 12.8.4.3 12.12.1 Table 12.6-1 16.3.4 12.3.3.1 12.3.3.4 12.3.4.2 12.7.3 12.8.4.3 12.12.1 Table 12.6-1 16.3.4 12.3.3.4 Table 12.6-1 12.3.3.4 Table 12.6-1 12.3.3.3 12.3.3.4 12.7.3 Table 12.6-1 16.3.4 12.5.3 12.7.3 Table 12.6-1 16.3.4 Seismic Design Category Application D, E, and F B, C, D, E, and F C, D, E, and F C, D, E, and F D, E, and F B, C, D, E, and F E and F D D B, C, and D C and D C and D D B, C, and D D, E, and F D, E, and F D, E, and F D, E, and F B, C, D, E, and F D, E, and F B, C, D, E, and F D, E, and F B, C, D, E, and F C, D, E, and F B, C, D, E, and F D, E, and F B, C, D, E, and F
12.8.4.2 Accidental Torsion. Where diaphragms are not flexible, the design shall include the inherent torsional moment (M₁) resulting from the location of the structure masses plus the accidental torsional moments (M₁) caused by assumed displacement of the center of mass each way from its actual location by a distance equal to 5% of the dimension of the structure perpendicular to the direction of the applied forces. Where earthquake forces are applied concurrently in two orthogonal directions, the required 5% displacement of the center of mass need not be applied in both of the orthogonal directions at the same time but shall be applied in the direction that produces the greater effect. Accidental torsion shall be applied to all structures for deter- mination if a horizontal irregularity exists as specified in Ta- ble 12.3-1. Accidental torsion moments (M₁) need not be included when determining the seismic forces E in the design of the structure and in the determination of the design story drift in Sections 12.8.6, 12.9.1.2, or Chapter 16, or limits of Sec- tion 12.12.1, except for the following structures: 1. Structures assigned to Seismic Category B with Type 1b horizontal structural irregularity. 2. Structures assigned to Seismic Category C, D, E, and F with Type la or Type 1b horizontal structural irregularity.