ÉCOLE NATIONALE DES PONTS ET CHAUSSÉES STRUCTURAL DESIGN FINAL PROJECT REPORT Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
TABLE OF CONTENTS STRUCTURAL DESIGN Project presentatjon 01 02 Primary assumptjons Loads defjnitjon 03 First statjc diagram 04 Secondary statjc diagram 05 2D numerical model 06 3D numerical model 07 3D linear analysis 08 3D non-linear analysis 09 Summary fjgures 10 Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
PROJECT PRESENTATION STRUCTURAL DESIGN The project consists in designing a cover for an archeological excavatjon area. The structure must be supported only by its edges. The structure would be used to observe the excavatjons and provide shelter for visitors. Site Constraints Minimal width of walkways : l min = 1,5 m Minimal total length of walways: L min ≥ 150 m At least three entrances : N, O, SE A minimal height under the structure is imposed : : • h min = 5 m for R > 15 m • h min = 8 m for 5 m < R < 15 m • h min = 10 m for R < 5 m Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
PROJECT PRESENTATION STRUCTURAL DESIGN Materials Materials used in this project are steel and polycarbonate. The structural elements are made out of steel while the cover would be made of polycarbonate. All elements of this design shall be calculated according to Eurocode 3. Posts | Beams | Structural Bracing Yield strength R e0.2 = 255 MPa Reductjon factor γ a = 1.0 Elastjc Modulus E = 210 GPa Specifjc weigth ρ = 7850 kg/m 3 Tie rods Yield strength R e0.2 = 1500 MPa Reductjon factor γ a = 1.2 Specifjc weigth E = 190 GPa Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
PRIMARY ASSUMPTIONS STRUCTURAL DESIGN Floor plan Cross Sectjon Elevation Static Diagram Sc: 1/1000 e Sc: 1/1000 Sc: 1/1000 Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
PRIMARY ASSUMPTIONS STRUCTURAL DESIGN Floor Plan Roof Plan Sc: 1/500 Sc: 1/500 Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
PRIMARY ASSUMPTIONS STRUCTURAL DESIGN Structural axonometry Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LOADS DEFINITION STRUCTURAL DESIGN Load types considered 1 Permanent load : G 3 Climatjc actjon : N (Snow) 2 Operatjng loads : Q 4 Climatjc actjon : V (Wind) Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LOADS DEFINITION STRUCTURAL DESIGN Load combinatjons ULS 1 1.35 G + 1.5 Q + 0.75 N 1.35 G + 1.5 Q’ + 1.35 V 2 3 G + 1.5 V Load combinatjons SLS 4 G + Q + 0.5N 5 G + Q’+ 0.5N Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
FIRST STATIC DIAGRAM STRUCTURAL DESIGN Shifu and stress analysis Shear and moment diagram under horizontal load Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
SECONDARY STATIC DIAGRAM STRUCTURAL DESIGN Statjc diagram with a Shear and moment diagram under vertjcal load tractjon ring Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
2D NUMERICAL MODEL STRUCTURAL DESIGN Shear and moment diagram | Load combinatjon 1 Modeled elements 1 Posts | HEB 300 2 Beam| HEB 300 3 Walkway | IPE 160 4 Tractjon ring| Support Results Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
3D NUMERICAL MODEL STRUCTURAL DESIGN First 3D model Modeled elements Shear and moment diagram | Load combinatjon 1 1 Posts | HEB 300 2 Beam| HEB 300 3 Walkway | IPE 160 2 4 4 Tractjon ring| Support 1 3 Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
3D NUMERICAL MODEL STRUCTURAL DESIGN Walkways Cross sectjons & necessary checks 1 Beams | IPE 160 2 Secondary Beams | IPE 80 3 Natural frequency Shear resistance 4 5 Vertjcal shifu Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
3D NUMERICAL MODEL STRUCTURAL DESIGN Posts and beams Cross sectjons & necessary checks 1 Posts | HEB 300 2 Beams| HEB 300 Bending resistancee 3 Shear resistance 4 5 Vertjcal shifu 6 Buckling analysis Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
3D NUMERICAL MODEL STRUCTURAL DESIGN Tie rods Cross sectjons & necessary checks 1 Tie rods | Ø 2 cm Tractjon resistance 2 Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
3D NUMERICAL MODEL STRUCTURAL DESIGN Anneaux primaires Cross sectjons & necessary checks 1 Compression ring | Ø 68 cm 2 Tractjon ring | Ø 20 cm Normal stress resistance 3 4 Buckling resistance Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
3D NUMERICAL MODEL STRUCTURAL DESIGN Secondary rings Cross sectjons & necessary checks 1 Secondary rings | Ø 50 cm 2 Normal stress resistance Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
3D NUMERICAL MODEL STRUCTURAL DESIGN Structural bracing Cross sectjons & necessary checks 1 Structural bracing | Ø 0.5 cm Normal stress resistance 2 Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN Moment [kN.m] Min Load cases analysis ULS 1 : 1.35 G + 1.5 Q + 0.75 N Max Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN Moment [kN.m] Min Load cases analysis ULS 3 : 1 G + 1.5 V Max Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN ULS 1 : 1.35 G + 1.5 Q + 0.75 N Normal stress diagram Moment stress diagram Transfer of thrust forces from the Bending transmitued by the beams to the tractjon ring and the compression ring at the center of the 1 2 compression ring structure Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN ULS 3 : 1G + 1.5 V Normal stress diagram Moment stress diagram Partjcipatjon of secondary elements ; Asymmetrical moment, shear and 1 2 structural bracings & secondary rings normal diagrams Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN Non-secondary role of the secondary rings 1 Tractjon stress : 270 kN 2 Compression stress : -270 kN Buckling analysis 3 4 Necessary increase of dimensions elements Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN Untensioned cables Untensioned cables in assymetrical 1 load cases 2 Necessity of pre-stressing cables Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN Structural bracing and structure response 1 Difgerentjated prestressing to minimize Difgerentjated prestressing to minimize 1 secondary forces secondary forces Lateral bracing replaced by beams 2 due to too secondary forces when prestrained Ɛ = 10 mm.m -1 & Ɛ = 20 mm.m -1 3 4 Compression stress transmited to the tractjon ring Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN Problems of compression stress in the tractjon ring 1 Compression stress due to assymetrical load and prestrain of structural bracing 2 Necessity to prestrain the traction ring Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
LINEAR ANALYSIS STRUCTURAL DESIGN Tractjon ring prestressing by tjltjng the posts 1 Self-prestressing of the tractjon ring mechanically diffjcult Traction stress in the traction ring due to the beam thrust forces being less 2 transmited to the posts Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
NON LINEAR ANALYSIS STRUCTURAL DESIGN Buckling analysis Buckling mode in the second 1 Buckling mode in the fjrst confjguratjon of bracings with a middle 1 confjguratjon of bracings set of bracings Buckling coeffjcient α = 2.5 2 Buckling coeffjcient α = 12 Necessity to rethink the structural 2 bracings Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
NON LINEAR ANALYSIS STRUCTURAL DESIGN Vertjcal shifu and structure’s natural frequency First structural height 1 h = 10m Walkways’ vertical shift 2 δ = -0.07 m > L/500 Natural frequency 3 f = 3.5 hz Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
NON LINEAR ANALYSIS STRUCTURAL DESIGN É tude de la fmèche By increasing the structural height, thrust forces are more transmitued to 1 the posts thus reducing the vertjcal shifu The formula f = 18/√(vertical shift) shows that reducing the vertical shift 2 also increases the natural frequency of walkways Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
FINAL OPTIMIZATION STRUCTURAL DESIGN Bracing tractjon resistance too low due 1 to too much prestraining Optimization of different elements 2 of the structure (bracings, beams and posts tilting) to increase cable resistance and maintaning the absence of compression stress in the traction ring. Beams : HEB 500 to increase 3 the effects of beams tilting by increasing permanent loads 4 Bracing cables : Necessity of high resistance steel ropes (3000 MPA) From Ø 0.5cm to Ø 0.9 cm Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
SUMMARY FIGURES STRUCTURAL DESIGN Support reactjon| SLU Structural work rate Vertjcal shifu 1 463 kN per posts 1 Beams | Bending : 57% 1 Beams f max / f authorized = 0.16 | Buckling : 34% Structural weight 2 Compression Ring| Compression : 10% 2 Walkways f max / f authorized = 0.8 2 W = 156 T 3 Tractjon Ring | Traction : 50% A = 1963 m 2 3 4 Tie cables | Traction : 13% W = 0.79 kN/m 2 4 5 Roof bracings | Traction : 95% 6 Lateral bracings | Bending : 17% Contreventement| Buckling : 33% Valentjn BATLLE | Paola TORRES | Aurélien DE BOIS
Recommend
More recommend
