CE 156 2nd Semester AY 2016 – 2017 DESIGN OF STEEL STRUCTURE: School Building located in Quezon City Submitted by: Eartha B. Becoñado 2011 – 45392 Submitted to: Dr. Oscar Victor M. Antonio, Jr. Date Submitted: 15 May 2017 I. Design Criteria and Load Calculations Structure The structure is a school building that has a total of 8 support reactions where 4 of which are fixed support and the other 4 are pin supports. There is a roof deck in the middle and designed to carry live loads as an assembly area. There is an assumed 5 inch thick concrete floor slab. The building is located in the vicinity of Quezon City on an adobe foundation with wide flanges of beams and columns and double-angle bars for the truss members. Figure 1. Structure Configuration Where, W1 = 8.71 kN/m2 applied to the 2nd floor of the building L = 7.13 meters B = 5.23 meters L/6 = 1.19 meters H1 = H2 = 3.0 meters H3 = 1.0 meter Figure 2. Geomtery of the Structure in STAAD Figure 3. Truss Details Figure 4. Purlins Details Load Calculations DEAD LOADS Minimum Densities for Design Loads for Materials from Table 204-1 Minimum Design Dead Loads from Table 204-2 Dead Loads for Ceiling Component Ceiling Mechanical Duct Allowance Suspended Steel Channel System Suspended Metal Lath and Gypsum Plaster Total Loads (kPa) 0.20 0.10 0.48 0.78 Dead Loads for Roof and Wall Coverings Component Coverings, Roof and Wall Three-ply ready roofing Deck, Metal 18 gage Fiber board, 13mm Water proofing membranes: Bituminous, smooth surface Total Loads (kPa) 0.05 0.14 0.04 0.07 0.30 Dead Loads for Floors Component Floor Lightweight Concrete Floor Fill (5 in): 0.015kPa per mm Concrete Fill Finish (30 mm) 0.023kPa per mm Total Loads (kPa) 1.905 0.690 2.595 Dead Loads for Concrete Component Concrete Masonry Units Lightweight Masonry Units: 16.5kN/m3 Wythe Thickness: 200 mm Grout Spacing: Full Plastered (2 faces) : 0.24 per face Total Loads (kPa) 3.59 0.48 4.07 Dead Loads for Roof Trusses Component Roof Trusses 2L8x8x5/8 Nominal Weight (kN/m) 0.9548 Dead Loads for Purlins Component Purlins 2L8x8x1/2 Nominal Weight (kN/m) 0.7709 Dead Loads for Beams Component Beams W14x48 Nominal Weight (kN/m) 0.7008 Dead Loads for Columns Component Columns W14x48 Nominal Weight (kN/m) 0.7008 LIVE LOADS Floor Live Loads Minimum Uniform and Concentrated Live Loads from Table 205-1 Floor Live Load Classroom uniform live load Assembly W1 Loads (kPa) 1.9 4.8 8.71 Roof Live Loads Minimum Roof Live Loads from Table 205-3 2.62 m 5.23 m 5.23 m 2.62 m 7.13 m Roof Truss Tributary Area (m2) Uniform Load (kPa) A B C D 18.68 37.29 37.29 18.68 1.00 0.75 0.75 1.00 Distributed Load (kN/m) 2.62 3.92 3.92 2.62 Symbol V Value 250 kph NSCP 2015 Fig 207A.5-1A Kd 0.85 Table 207A.6-1 I 1.00 Table 208-1 Kh, Kz 0.65 Section 207A.7 Kzt 1.00 Section 207A.8.2 G See Reference Section 207A.9 GCpi +0.18, -0..18 Table 207A.111 Cp See Reference Figure 207B.4-1 WIND LOADS Location: Quezon City Parameter Basic Wind Speed Wind Directionality Factor (for MWFRS) Importance Factor (Occupancy Category: I Standard Category) Velocity Pressure Exposure Coefficients (Exposure Category: B, 7m ) Topographic Effects Gust Effect Factor (for Rigid Buildings) Internal Pressure and Force Coefficients (for Enclosed Buildings) External Pressure and Force Coefficients Provided parameters may be used to compute for the velocity pressure qz, ππ§ = 0.613 × 0.65 × 1.0 × 0.85 × 69.442 π/π ππ§ = 1633.1 Roof Angle 5 20 11.9 GCpi 0.18 -0.18 GCpi 0.18 -0.18 1 0.40 0.53 0.46 GCpf- GCpi 0.28 0.64 0.46 1.04 π ππ ππ 1.63 2 2 π π External Pressure Coefficients, GCpf Building Surface 2 3 4 1E 2E -0.69 -0.37 -0.29 0.61 -1.07 -0.69 -0.48 -0.43 0.80 -1.07 -0.69 -0.42 -0.35 0.70 -1.07 3E -0.53 -0.69 -0.60 4E -0.43 -0.64 -0.53 -0.87 -0.51 -1.25 -0.89 -0.78 -0.42 -0.71 -0.35 -2.04 -1.45 -1.27 -0.68 -1.16 -0.57 -1.42 -0.83 -0.60 -0.53 0.52 -0.24 -0.17 0.88 P = qz [GCpf- GCpi] -0.98 -0.86 0.85 -0.39 -0.28 1.43 kN/m2 1.43 -2.04 -1.27 -1.16 -0.82 -0.82 Surface 1/1E 2/2E 3/3E 4/4E 5 6 EARTHQUAKE LOADS Parameter Seismic Importance Factor, I Soil Profile Type: Adobe Seismic Zone Factor, Z Seismic Source Type Near Source Factor, Na Near Source Factor, Nv Seismic Coefficient, Ca Seismic Coefficient, Cv Structure Period, T Numerical Coefficient, R Value 1.50 SA 0.4 A 1.5 2 0.48 0.64 0.327 8.0 NSCP 2015 Table 208-1 Section 208.4.3.1.1.2.4 Table 208-3 Table 208-4 Table 208-5 Table 208-6 Table 208-7 Table 208-8 Equation 208-12 Table 208-11A Total Dead Load = 2378.53 kN DESIGN BASE SHEAR 0.11πΆπ πΌπ = 0.11 × 0.48 × 1.50 × 2378.53 ππ = 188.4 ππ 0.8 π ππ£ πΌ π = 285.4 ππ π π= πΆπ£ πΌ π = 872.9 ππ π π 2.5πΆπ πΌ π = 535.2 ππ π Design Base Shear = πππ. π ππ΅ Level 1 2 3 II. V 535.2 Wi 459.96 1303.404 615.16 hi 7 6 3 wh 3219.72 7820.42 1845.48 V-Ft 412.7 412.7 412.7 Ev 103.12 250.48 59.11 Total 515.82 663.18 471.81 STAAD Analysis Results Node 1 13 13 16 19 13 13 13 22 13 22 1 Fx kN 65.119 -66.574 -66.574 13.241 -0.885 -66.574 -66.574 9.349 7.291 9.349 -53.813 65.119 Fy kN 239.659 718.718 718.718 -25.077 621.069 718.718 718.718 -0.439 -13.511 -0.439 159.214 239.659 Fz kN 2.075 -48.98 -48.98 0.06 39.618 -48.98 -48.98 -6.524 -0.762 -6.524 5.217 2.075 Mx kNm 4.251 15.147 15.147 0 0 15.147 15.147 -11.794 -1.167 -11.794 9.813 4.251 My kNm -0.007 -0.005 -0.005 0 0 -0.005 -0.005 -0.092 0.015 -0.092 -0.001 -0.007 Mz kNm -66.4 17.683 17.683 0 0 17.683 17.683 -29.38 -14.566 -29.38 57.391 -66.4 Component Beams and Columns Trusses Purlins III. Initial Section Optimized Section W14x48 Fail W24x117 2L8x8x5/8 Fail 2L8x8x5/8 2L8x8x1/2 Pass L7x4x1/2 Largest Optimized Section was Chosen Pass Pass Pass AISC Manual Design and STAAD Design Results and Comparison Manual Calculation Results The following are the manual calculations for getting the sections for the structure and the results. Data were taken from the post processing tab in STAAD. Critical parts/sections were chosen. BEAMS Forces Load Combination Beam No. Max +Fx 2 Max -Fx 2 1.2D + 1.6W + 0.5 Lr + 0.5L 1.2D + 1.6W + 0.5 Lr + 0.5L kN Kips 715.108 103.72 -93.532 -13.55 Considering tension: Where πππ = ππΉπ¦ π΄π ≥ ππ’ Substituting the values to equation, ππ’ = 103.72 ππππ π = 0.9 πΉπ¦ = 50ππ π π΄π = 2.3 ππ2 Using AISC Table 1-15, the section based on the required Ag, 2L3 1/2 x 2 ½ x 1/4 with an π¨π = π. π πππ Considering compression given the data: ππ’ = −13.55 ππππ πΉπ¦ = 50ππ π πΈ = 29000ππ π ππΏ = 60 π Use equation from AISC, πΈ ππΏ 4.71√ = 113.43 > πΉπ¦ π Use πΉπ¦ πΉππ = πΉπ¦ [0.658πΉπ ] πΉππ = 21.78 Using Equation, πππ = ππΉππ π΄π ≥ ππ’ π΄π = 0.69 ππ2 2L2 x 2 x 1/8 with an π¨π = π. ππ πππ PURLINS Forces Purlin No. Max +Fx 38 Max -Fx 38 Load Combination 1.2D + 1.6W + 0.5 Lr + 0.5L 1.2D + 1.6W + 0.5 Lr + 0.5L Considering tension: Where πππ = ππΉπ¦ π΄π ≥ ππ’ Substituting the values to equation, ππ’ = 0.24 ππππ π = 0.9 πΉπ¦ = 50ππ π kN Kips 1.675 0.24 -1.542 -0.22 π΄π = 0.005333 ππ2 Using AISC Table 1-15, the section based on the required Ag, 2L2 x 2 x 1/8 with an π¨π = π. ππ πππ Considering compression given the data: ππ’ = −0.22 ππππ πΉπ¦ = 50ππ π πΈ = 29000ππ π ππΏ = 60 π Use equation from AISC, πΈ ππΏ 4.71√ = 113.43 > πΉπ¦ π Use πΉπ¦ πΉππ = πΉπ¦ [0.658πΉπ ] πΉππ = 21.78 Using Equation, πππ = ππΉππ π΄π ≥ ππ’ π΄π = 0.0112 ππ2 2L2 x 2 x 1/8 with an π¨π = π. ππ πππ COLUMNS Forces Max +Fx Column No. Load Combination kN-m Kips-ft 87 1.2D + 1.6W + 0.5 Lr + 0.5L 225.103 166.027 πππ = ππΉπ¦ ππ₯ ≥ ππ’ ππ₯ = 3.69 ππ2 Using Table 3-2 of AISC, the section satisfying Z Use W8x10 With Zx=8.9 but shape exceeds compact limit so use Use W8x13 with Zx = 1.14 IV. Connection Design and Detailing TRUSS CONNECTIONS Section Connection Base Metal Thickness Type of Weld Filler Metal (AISC J-6) Minimum Size of Weld (Table J2.4) Factored Load, T Section Ag An U Ae 2L2 ½ x2 ½ x3/8 LLBB Welds A992 3/8” Fillet Weld 70 ksi 1/8” 103.72 kips 2L2 ½ x 2 ½ x 3/8 LLBB 3.47 in2 3.47 in2 0.9 3.123 in2 Strength of Base Metal Yielding πππ = ππΉπ¦ π΄π = 0.9 π₯ 50 π₯ 3.47 = 156.15 ππππ Rupture πππ = ππΉπ’ π΄π = 0.75 π₯ 65 π₯ 3.123 = 152.25 ππππ Strength of Weld per Unit Width ππ ππ€ = ππ‘π πΉπ€ = 0.75 π₯ 0.707 π€ π₯ 0.66πΉπΈπ₯π₯ = 2.78 ππππ /ππ Solving for Length of Weld 2 ∑ π: 0 = πΉ2 (2) + πΉ2 − 152.25 ππππ ∗ 0.758 2 = 2.784 πΏ1 (2) + 2.784 (2) − 152.25 ππππ ∗ 0.758 π³π = ππ. ππ ππ ≈ ππ ππππππ π³π = ππ. ππ ππ ≈ ππ ππππππ Checking for U, π= π1 + π3 = 26.5 ππ 2 π= 1− π₯ = 0.99 πΏ Using U, πππ = ππΉπ’ π΄π = 0.75 π₯ 65 π₯ 0.99 π₯ 3.47 = 167.7 ππππ Yielding governs. Solving for the length of weld usingπππ = 156.15 ππππ , ∑ π = 0 = 2.784 πΏ1 (2) + 2.784 (2) − 156.15 ππππ ∗ 0.758 π³π = ππ. ππ ππ ≈ ππ ππππππ π³π = ππ. ππ ππ ≈ ππ ππππππ BEAMS AND COLUMNS CONNECTIONS Connection Bolt (J3.2 High strength) Diameter of bolt Nominal Tensile Stress, Fnt Fnv Minimum bolt pretension (Table J3.1) U (Clean Mill Scale Class A) Du Hsc Ns Slip-critical A490 7/8 in 113 ksi 75 ksi 49 kips 0.35 1.13 1.0 1.0 ππ’ = 103.72 ππππ ππ ππ€ = ππ’π·π’ βπ π ππ ππ ππ ππ€ = (1)(0.35)(1.13)(1)(1)(49) = 19.38 πππ ≥ ππ’ = 103.72 ππππ = πππππ‘π × ππ ππ€ πππ¨π₯ππ¬ = π. ππ ≈ π ππ¨π₯ππ¬ Detailed Plan of connection for beams and columns References: 1. American Institute of Steel Construction Manual, 14th Edition 2. Association of Structural Engineers of the Philippines (2010). National Structural Code of the Philippines 2010 (6th ed.). Quezon City, Philippines: Association of Structural Engineers of the Philippines 3. Salmon, C.G., Johnson, J.E. and Malhas, F.A. (2009) Steel Structures Design and Prentice Hall, 5th edition. Behavior,
