BTL kết cấu thép

STEEL STRUCTURE ASSIGNMENT Full Name: Student Code: Course: Majors: Project supervior: Steel Structure I Bộ môn Kết Cấu DESIGNED MISSION Design a main girder, simple span on bridge way for car with “I” section, un-composite steel girder, flange and girder wall connected by weld line in the factory and construction joint by high-pressure bolt II HYPOTHETICAL METRICS Girder length (calculated span) L = 14m Designed lanes nL = lanes Main beam distance Sd = 1.8 m Dead load on reinforced concrete deck wDC2 = kN/m Dead load of wearing surface and utilities wDW = kN/m Designed car live load (with road level coefficient) Average Daily Traffic ADT Truck on lane ratio HL – 93 ADT = 1.5104 Vehicle/day/land k = 0.15 Lateral moment distribution coefficient mgM = 0.65 Lateral shear distribution coefficient mgV = 0.6 Lateral deflect distribution coefficient mgD = 0.45 Lateral fatigue distribution coefficient mgF = 0.5 Road level coefficient Allowable deflection of live load m = 0.5 ∆χπ = Λ/800 Material + Steel designed for girder M270 lever 345 + High-pressure bolt ASTM A490M Designed standard TCVN11823-6:2017 Steel Structure Bộ môn Kết Cấu Table of contents I II III IV V VI VII Select girder section, calculate signature geometry Calculate and Draw internal forces diagram by influence line method Check girder by strength limit state Check girder by service limit state Check girder by fatigue limit state Calculate and design stiffener Calculate and design joint construction I Select girder section Girder section is selected by trial and error method, it means we select girder section size respectively by experience and control regulation of design standard, and check again If it don’t meet the requirements, we choose and check again Process is repeated until it meets the requirements Steel Structure Bộ môn Kết Cấu 1.1 Steel girder height d (mm) The height of main beam has big influence to construction’s price, so we have to consider it carefully when select this value To car bridge way, simple span, we can choose them basically by experience With simple bridge beam, I section of un-composite reinforced concrete deck: Height of girder d should be chosen evenly to 5cm We have: L = 14m = 0.56 (m) = 0.7 (m) = 1.16 (m) Choose: d = 1100mm 1.2 Select beam wing, beam bottom Flange’s width can be selected basically by this experience equation: We have: Steel Structure Bộ môn Kết Cấu d = 1100 (mm) = 366.67 (mm) = 550 (mm) So we choose: Upper compressed flange’s width bfc = 400 mm Lower compressed flange’s width bft = 400 mm 1.3 Flange’s width and girder web: Follow the requirement of procedure (A6.7.3), the minimum thickness of flange, girder web is 8m This minimum thickness is used for corrosion counter and transporting requirement, collapsing in construction Requirements of ASTM A6M, we have: 5.0, 5.5, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 14.0, 16.0, 18.0, 20.0, 22.0, 25.0, 28.0, 30.0, 32.0, 35.0, 38.0, 40.0, 45.0, 50.0, 55.0, 60.0,… 160.0, 180.0, 200.0, 250.0, 300.0 (mm) We choose: Upper compressed flange’s thickness: tc = 25 (mm) Lower compressed flange’s thickness: tt = 25 (mm) Girder web’s thickness: tw = 14 (mm) So height of girder web is: D = d - tt - tc = 1050 (mm) Check section ratio: Marker 10.2 of TCVN 11823-6:2017 introduce these limit dimension of lateral section: Girder web ratio Girder web without vertical stiffeners Flange ratio This is the limitation in realistic to make sure that flange will not get over-deformed when weld it to girder web After choosing, girder section has this figure: Steel Structure Bộ môn Kết Cấu 1.4 Calculate geometrical characterisitcs beam section Section Ai (mm2) hi (mm) Aih i (mm3) I0i (mm4) Aiyi2 (mm4) Ii (mm4) Upper flange 10000 1087.5 10875000 520833 2889062500 2889583333 Girder web 14700 550 8085000 1350562500 1350562500 Lower flange 10000 12.5 125000 520833 2889062500 2889583333 Total 34700 550 19085000 1351604167 5778125000 7129729167 Where: A = section area “i” (mm2) i h = distance from median point of section “i” to bottom girder (mm) i I = inertia moment of section “i” with cross axis through its median point (mm 4) 0i = distance from median point of section “i” (mm) yi = (mm) Ii = I0i + Ai.yi2 (mm4) Follow the table, we have: Section Steel ybot (mm) 550 ytop (mm) 550 ybotmid (mm) 537,5 ytopmid (mm) 537,5 Sbot (mm3) 1.296.10 Stop (mm3) 1.296.10 Sbotmid (mm3) 1.326.10 Stopmid (mm3) 1.326.10 Steel Structure Bộ môn Kết Cấu 7 7 beam ybot = distance from median point of girder section to under lower flange steel girder (mm) ytop = distance from median point of girder section to top of upper flange steel girder (mm) ybotmid = distance from median point of girder section to median point of under flange steel girder (mm) ytopmid = distance from median point of girder section to median point on top of flange steel girder (mm) Sbot = Bending moment resistance of girder section with ybot (mm3) Stop = Bending moment resistance of beam section with ytop (mm3) Sbotmid = Bending moment resistance of beam section with ybotmid (mm3) Stopmid = Bending moment resistance of beam section with ytopmid (mm3) 1.5 Calculate girder dead load Girder dead load on one meter long: WDC1 = A = 0.0347.7850.10 = 2723.95 (N/m3) = 2.723 (kN/m3) II Calculate and draw internal forces diagram 2.1 Calculate M, V by influence line method: Split girder to equal parts Choose Nđ = 10 parts Length of each part: Lđ = 1.4 m We numbered the beam section parts respectively Moment influence line value: Section xi (m) 1.4 2.8 4.2 5.6 7.0 Where: Dah Mi (m) 1.26 2.24 2.94 3.36 3.5 AMi (m2) 8.82 15.68 20.58 23.52 24.5 10 Steel Structure Bộ môn Kết Cấu xi = distance from abutment to i section Dah Mi = Ordination of Influnce line Mi AMi = Area of influence line Mi We have moment influence line figure of beam sections: 10 Ðah M1 1.26 Ðah M2 2.24 Ðah M3 2.94 Ðah M4 Ðah M5 3.36 3.5 Adjust load Coefficient for limit strength state We consider total loads: + Live load (HL-93) + Dead load of structural components and nonstructral attachments, reinforced concrete surface deck (DC) + Dead load of wearing surface and utilities (DW) Moment in random section is calculated by these equation: + Strength limit state I Steel Structure Bộ môn Kết Cấu + Service limit state Where: LL = designed lane load = uniform load = 9.3 = Effects of designed truck at “i” section = Effects of designed tandem at “i” section mgM = Lateral distribution coefficient calculated for moment (and lane ratio m) wDC = Dead load of girder on a unit length wDW = Uniform load by wearing surface and utilities IM = Impact factor = 0.33 AMi = Area of influence line Mi k = Road level coefficient or reduction factor live load for designed car 1,0; 1,25; 1,3; 1,5, 1.75 = Load coefficient by requirement of load combination TCVN 11823:2017 Arrange design trucks and tandems on influence line to find out orientation values influence line correspond with each car axle to each influence line We have Steel Structure Bộ môn Kết Cấu 145kN 145 kN 35 kN 4300 4300 Ðah M1 y1 y3 y2 110 kN 0.4 0.83 1.26 110 kN 1200 Ðah M1 1.26 1.14 y4 y5 145kN 145 kN 4300 35 kN 4300 Ðah M2 1.38 y3 2.24 y2 110 kN 110 kN 1200 Ðah M2 2.24 y4 y5 0.52 y1 10 ...Steel Structure I Bộ môn Kết Cấu DESIGNED MISSION Design a main girder, simple span on bridge way for car with “I” section,... 345 + High-pressure bolt ASTM A490M Designed standard TCVN11823-6:2017 Steel Structure Bộ môn Kết Cấu Table of contents I II III IV V VI VII Select girder section, calculate signature geometry... choose and check again Process is repeated until it meets the requirements Steel Structure Bộ môn Kết Cấu 1.1 Steel girder height d (mm) The height of main beam has big influence to construction’s