Steel design standards comparison

Steel Design Standard in Comparison US vs EU vs VN A U T H O R : TA I V N G U Y E N – H O N O R B A C H E L O R O F C I V I L E N G I N E E R GRIFFITH UNIVERSITY Presentation Part 1: Comparison Between Steel Design Standards (US, EU & VN) Part 2: Design Practice Results Part 1: Scope of Study •Standard’s Philosophy •Load Combinations •Design Standard Principles Part 1: Comparison Steel Design Standards (US, EU & VN) Standard Philosophy US: AISC-360 (American Institute of Steel Construction) EUROCODE (EN 1993) TCVN • ASD: Allowable Stress Design • LRFD: Load & Resistance Factor Design LSD: Limit Stage Design LSD: Limit Stage Design ASD: This technique is based on pure elastic theory, with this method, the stresses produced from all the Static (Dead and Live) Loads and Dynamic Loads should not exceed the stipulated allowable Stress in the structural members and their connections LRFD: “A limit state is a condition that represents a boundary of structural usefulness beyond which the structure ceases to fulfil its intended function.” (Vinnakota, 2005, pp 125 – 125) Ultimate Limit States & Serviceability Limit States COMPARISON ASD Fa= required strength, Fn = nominal strength Ω = safety factor ≥ Fn/Ω = allowable strength Qt1, Qt2 = Nominal transient load effects Qd = Nominal dead load effect γ = Load factor LRFD US: AISC-360 (American Institute of Steel Construction) Load Combination 1.ASD 7-05: DL+LR DL+WL 0.6DL+WL 0.6DL+0.7SE DL+0.75(LR+WL) 2.ASD 7-10: DL+LR DL+0.6WL 0.6DL+0.6WL 0.6DL+0.7SE DL+0.75(LR+0.6WL) 3.LRFD: 1.4DL 1.2DL+1.6LR+0.5LF 1.2DL+0.5LR+1.6LF 1.2DL+1.6LR+0.8WL 1.2DL+0.5(LR+LF)+1.6WL 1.2DL+0.5LF+1.0SE 0.9DL+1.0SE 0.9DL+1.6WL EUROCODE (EN 1993) 1.25DL+1.5LR+EHF 1.25DL+1.5SL+0.75WL+EHF 1.25DL+1.5WL+0.75SL+EHF TCVN 1.35DL+1.5WL+EHF TT+HT TT+0.9HT+0.9GX TT+0.9HT-0.9GX TT+0.9HT+0.9GY TT+0.9HT-0.9GY DL+AA+EHF DL+AA+0.2WL+EHF TT+0.8 HT+0.8(DDX+0.3DDY) TT+DDX+0.3DDY ASD VS LRFD ASD LRFD Factors of safety (uncertainty & variability in loads and resistance) were NOT from analysis but from combination of experience and experiments Single factor of safety Ω is used Load factors & resistance factor are used to handle uncertainties Evaluation: LRFD is advantageous over ASD, because distributing different factors depending on load type as LRFD does brings about a more effective design with lighter members ASD VS LRFD The factor of safety in ASD is a ratio of the load factor over the resistance factor of LRFD • Live load/dead load = 3, ASD will produce members of same structural integrity and same member sizes as LRFD • But Live load/dead load ≠ 3, designs produced by ASD are either less efficient or less reliable or both as compared to LRFD which is relatively more rational in its designs ASD VS LRFD • Both codes cannot be used in the same design • There is no particular recommendation to which code to use It’s all up to designer Decisions are generally made based on finance Source: 2006,2008 T.Bartlett • LRFD designs gets the most out of material strength, thereby should be a more economical approach ASCI-360 vs EC3: Material Asci-360 vs ec3: Material Table: Steel Grade Equivalences AISC-360 vs EC3: TENSION DESIGN Tensile Yield Strength is calculated for both: Tensile Fracture Strength: • AISC-360: • EC3: Comment: main difference is U (Shear Lag Factor) EC: U =0.9 AISC: U = 0.6 - AISC-360 vs EC3: COMPRESSION DESIGN SUMMARY American Wind Load ASCE 360-05: giây, chu kì 50 năm EC3: giây, chu kỳ 50 năm ASCE 360-10: giây, chu kì 700 BS 6399: giờ, với chu kỳ 50 năm năm Live Load 57 kG/m2 (Mái:tôn xà gồ) Seismic EU UBC 97 Zone (1, 2A, 2B, 3, 4) TCVN QCXDVN 02-2008 BXD: 10s, chu kỳ 20 năm 60 kG/m2 – mái đốc 30o 30 kG/m2 (ATAD) Tính theo gia tốc agR (%g) IBC: Ss (%g), S1 (%g) Tính theo gia tốc agR (%g) Nếu gia tốc agR < 0.08m/g² => khơng cần tính động đất • Gió lớn, địa hình vùng C → tổ hợp ASCE 7-10 có lợi • P/s: -Hệ số chuyển đổi vận tốc gió trung bình giây từ chu kì lặp 20 năm (TCVN)->sang 50 năm (ASCI360-05) 1.2 -Hệ số chuyển đổi vận tốc gió trung bình giây từ chu kì lặp 20 năm (TCVN)->sang 700 năm (ASCI360-10) 1.391 Reference • AISC 360-05 (2005) Specification for Structural Steel Buildings American Institute of Steel Construction, Inc., Chicago, IL • AISC 360-10 (2010) Specification for Structural Steel Buildings American Institute of Steel Construction, Inc., Chicago, IL • EN 1993-1-1 (2003) Eurocode 3: Design of Steel Structures- Part 1-1: General Rules and Rules for Buildings European Committee for Standardization, Brussels • Topkaya, C., & Şahin, S (2011) A comparative study of AISC-360 and EC3 strength limit states International Journal of Steel Structures, 11(1), 13-27 doi:10.1007/s13296-0111002x • Yann Steve Siewe Tchoussonnou (2015) A brief comparison between Eurocode and American AISC-360 in design large span structure Part 2: Design Result PROJECT INFORMATION INPUT: • Bay = 9m, H (EH) = 10m • Wind: 200km/h (territory C) • DL: 10kg/m2 • LL: 30kg/m2 • Seismic: Zone (Na=1, Nv=1) • Frame style: Clear Span (MS) • Slope: 15% with 30-45m span, 20% with 50-100m span OUTPUT • ASD 360-10/ASCE 7-10 • ASD 89/ ASCE 05 Analysis Assumption: G=10kN/m2 => DL=0.9 kN/m ; Lr=0.3 kN/m Wind speed: Ignore the difference wind speed calculation in ASCE 05 vs ASCE 07-10 => Wind Load was calculated using the ATAD Excel file Assumption: L=100m Acceptable Optimized Result: Vertical & Horizontal Deflection satisfy Standard ASD Stress ratio ≥ 0.9 : more than 50% in SAP model RESULT Span (m) ASD 89/ASCE 07-05 (Kg/frame) ASD 360-10/ASCE 07-10(Kg/frame) 30 4029 5142 35 4634 5832 40 5528 6925 45 6625 8235 50 9057 9941 55 8983 10.520 60 11.161 12.604 65 12.914 15.008 70 15.689 18.291 75 17.613 20.361 80 19.764 23.097 85 21.624 26.810 90 24.612 28.237 95 27.656 33.236 100 31.068 35.914 THANK YOU ... Between Steel Design Standards (US, EU & VN) Part 2: Design Practice Results Part 1: Scope of Study •Standard’s Philosophy •Load Combinations Design Standard Principles Part 1: Comparison Steel Design. .. Design Standards (US, EU & VN) Standard Philosophy US: AISC-360 (American Institute of Steel Construction) EUROCODE (EN 1993) TCVN • ASD: Allowable Stress Design • LRFD: Load & Resistance Factor Design. .. for Structural Steel Buildings American Institute of Steel Construction, Inc., Chicago, IL • AISC 360-10 (2010) Specification for Structural Steel Buildings American Institute of Steel Construction,