CIVL3811 Bridge Engineering Lecture Slides (Week 7) 2022 PDF

Introduction to Bridge Engineering ( Part 2) CIVL3811 Engineering Design and Construction School of Civil Engineering | Faculty of Engineering THE UNIVERSITY OF SYDNEY The University of Sydney Page 1 Overview In Australia, bridges are designed in accordance with AS5100:2017 Br...

Introduction to Bridge Engineering ( Part 2) CIVL3811 Engineering Design and Construction School of Civil Engineering | Faculty of Engineering THE UNIVERSITY OF SYDNEY The University of Sydney Page 1 Overview In Australia, bridges are designed in accordance with AS5100:2017 Bridge Design Code It has 8 Parts 1. Part 1: Scope and general principles 2. Part 2: Design loads 3. Part 3: Foundations and soil-supporting structures 4. Part 4: Bearings and deck joints 5. Part 5: Concrete 6. Part 6: Steel and composite construction 7. Part 7: Bridge assessment 8. Part 8: Rehabilitation and strengthening of existing bridges 9. Part 9: Timber https://theconstructor.org/structures/bridge-design-loads/21478/ The University of Sydney Page 2 Design Loads 1. Permanent Load i. Dead Load ii. Super Imposed loads iii. Earth Pressure iv. Creep and Shrinkage https://www.midasbridge.com/en/solutions/moving-load- analysis v. Forces from Bearings vi. Water Flow forces (NWL) vii. Differential Movements https://www.midasbridge.com/en/solutions/moving-load-analysis The University of Sydney Page 3 Design Loads 2. Transient i. Road Traffic – W80, A160, SM100, M1600, HLP 320/400, DLA, ALF, Centrifugal Forces, Braking Loads, Barrier Impact Loads, Fatigue vehicle ii. Rail Traffic- 300LA, 150LA, braking, Nosing iii. Pedestrian iv. Water Flow Forces v. Thermal vi. Seismic vii. Collision viii.Wind loads ix. Earth Pressure due to LL https://www.fox8live.com/2018/11/20/traffic-down-one-lane-veterans-memorial-bridge/ The University of Sydney Page 4 Design Loads are determined in accordance with Part 2 – Dead Loads – Traffic Loading – Dynamic Load Allowance – Horizontal Traffic Loads – Impact Loading – supports – Barrier Loads – Environmental Loads and other effects https://engineeringcivil.org/articles/impact-factor-dynamic-allowance-design-causes-characteristics-bridge-loads/ https://www.sciencedirect.com/science/article/pii/S2095809917300899 The University of Sydney Page 5  General Issues for Design Loads First drawings must contain the following: – Conformance statement for minimum design loads – Types of specific traffic loads (eg: T44) and lateral position for special loads – Allowance for collision loads where relevant – Assumed wind, flood, and seismic load events – Foundation data and differential settlement https://todconsulting.com/handrail-design-australia- 2/ allowances, where applicable The University of Sydney Page 6  Dead Loads – Self weight of superstructure – Self weight of sub structure https://www.bridgetech-world.com/blogs/the-bridge-club/incremental-launching – Imposed dead loads, such as surface materials, utilities & services, overlays (both structural and non-structural) https://www.midasbridge.com/en/solutions/substructure s The University of Sydney Page 7 Traffic Loading – Determination of maximum load effect due to the movement of the vehicle across a bridge and bridges shall be designed to resist these loads. – Design Loads:(refer to AS 5100.2:2017) – M 1600 moving traffic load – S 1600 stationary traffic load – Heavy Load Platforms (HLP): HLP 320 or HLP 400, if specified by the relevant authority – W 80-wheel load – A 160-axle load – Accompanied Lane Factors (refer to Table 7.6) – Other loads (refer to Part 7) The University of Sydney Page 8 Traffic Load (Q) Road Traffic Pedestrian Traffic-5 kPa Rail Traffic-300LA nominal rail traffic load https://engineeringcivil.org/articles/10-design-loads-bridges-highway-rail-bridge-miscellaneous- loads/ The University of Sydney Page 9 Design Loads for Bridges According to AS5100 1) W80 wheel load, 2) A160 axle load, 3) M1600 moving traffic SM 1600 Loads 4) M1600 moving tri-axle group load, 5) S1600 stationary traffic load, 6) HLP320 or HLP400, if specified by the relevant authority, 7) Dynamic load allowance, 8) Number and position of traffic lanes, 9) Accompanying lane factors, 10) Centrifugal forces, 11) Braking forces, 12) Fatigue load 13) Pedestrian load The University of Sydney Page 10 Dynamic load allowance https://www.frontiersin.org/articles/10.3389/fbuil.2021.660292/fu Gao, Q.F., Wang, Z.L., Li, J., Chen, C. and Jia, H.Y., 2015. Dynamic load allowance in different positions of the multi- ll span girder bridge with variable cross-section. Journal of Vibroengineering,17(4), pp.2025-2039. The University of Sydney Page 11  Horizontal loads - Environmental Effects – Wind – SLS – 20-year return period – ULS – 2000-year return period – Need to calculate drag co-efficient – Thermal – Hydraulic – Water flow – Flood debris and log impact – The University of Sydney Page 12  Earthquake Effects – Quasi-static horizontal loads – Vertical loads – Soil behaviour/influences – Ductility – Restraints The University of Sydney Page 13  Other Load effects – Shrinkage, Creep, and Prestress – Differential settlement / subsidence – Particularly in mining areas – Construction Loads – Dynamic Behaviour – Tends to be a highly specialised analysis – Can lead to major problems/damage if not addressed The University of Sydney Page 14 Design for Durability AS 5100.5 – Section 4 1. Exposure Classifications: A, B1, B2. C1, C2 – 2. Arid environments to Tidal and Splash zone 3. Design Life to meet 100years 4. Selection of Concrete Cover i. Precast, Cast in place ii. Concrete grade iii. Supplementary materials 5. Limiting crack widths https://www.steelconstruction.info/Bridges_- _initial_design The University of Sydney Page 15 Design for Fire AS 5100.2 1. Hydrocarbon Fire i. Cut and Cover structures ii. Hydrocarbon Fire curves 2. Cellulosic Fire i. Bush fire-prone areas 3. Increased Cover 4. Reduced steel stress 5. Concrete spalling https://www.researchgate.net/publication/310386742_Detailed_Analysis_of_the_Causes_of_Bridge_Fires_and_Their_Associated _Damage_Levels/figures The University of Sydney Page 16  Load Combinations – Identification of relevant limit states – SLS – Deflection – Vibration and dynamic responses – General functionality of the bridge – ULS – Strength considerations – Defining the likely/possible load combinations – Worst Case Scenarios The University of Sydney Page 17  FRANCIS SCOTT KEY BRIDGE The University of Sydney Page 18  Francis Scott Key Bridge The University of Sydney Page 19  Strand7 model of the Francis Scott Key Bridge The University of Sydney Page 20 The University of Sydney Page 21  M1600 Moving Traffic Load (Standards Australia, 2004) The University of Sydney Page 22  Dynamic Load – As explained in Clause 6.9 AS5100, the dynamic load shall be model with a single M1600 moving traffic load, without UDL. The dynamic load allowance is 0.3. Hence each concentrated load is equal to 60 kNX1.3=78kN. Due to the time and technical restraints, the dynamic analysis was conducted by placing the concentrated load in various position of the bridge. 7 most critical dynamic load positions were considered when dynamic analyses were carried out on the bridge. All of the dynamic loading cases were shown in the next Figure. The University of Sydney Page 23  Dynamic Load The University of Sydney Page 24  Static analysis – The static analysis was carried out on the model with nonlinear static solver in strand7. The diagrams in the next pages were the beam and plate stress analysis of a bridge in static condition for ultimate strength. The maximum stress was calculated to be 600 MPa, which occurred at the arc member near the supports. – The maximum stress experienced by concrete deck was determined under Von Mises criterion for ultimate strength requirement. The maximum stress of 49.8 MPa occurred at the beginning of the over handing deck on the top surface. However, this is not the case in the actual bridge since the deck is not connected with the truss and the actual stress could be much lower than that. The maximum stress on the other place of the deck was only about 30 MPa. The University of Sydney Page 25  Static analysis beam axial stress for static analysis for ultimate strength The University of Sydney Page 26  Static analysis maximum stress on the deck The University of Sydney Page 27  Dynamic analysis – In dynamic design, the diagrams illustrated the critical situations when loading applied to a specific position. The maximum stresses of truss member was found to be 322 Mpa, which occurred at the arc member near support as well as shown in The current Figure. The University of Sydney Page 28  Bridge Serviceability – According to Australian Strand AS5100.2 Clause 6.11, the deflection for serviceability limit state shall be not greater than 1/600 of the span. For a 366m span bridge, the maximum deflection should not exceed 0.61m. The following Figures are the deflection under 1.0G+1.0Q and 1.0G respectively. By subtracting the 1.0G from 1.0G+1.0Q, the deflection for live load can be obtained. The University of Sydney Page 29  Bridge Serviceability deflection under self-weight and traffic load The University of Sydney Page 30  Verrazano Narrows Bridge – Static/Dynamic Analysis – Verrazano Narrows Bridge connects Staten Island with Brooklyn in New York City. The bridge was designed by chief engineer Othmar Ammann. The design is a double deck suspension bridge with the capacity to carry traffic on both the upper and lower decks of the bridge. It is the 11th longest single span suspension bridge in the world. – Construction began in 1959 and took 5 years to complete at a cost of $320 million. Over 1 million bolts and 3 million rivets were used to construct this bridge. The road deck is primarily supported via the steel hanger cables with secondary support from the truss base between the two road decks. The main cable system forms a centenary shape and provides restraint for the suspension cables. The bridge only has two towers with a height of 210m. The towers are 41mm further apart at the top due to the curvature of the earth. – The bridge is currently used by both traffic, pedestrian and cyclists with an average of 170,000 people using the bridge each day. The University of Sydney Page 31  Verrazano Narrows Bridge The University of Sydney Page 32  Simplified cables, modelled in Strand7 The University of Sydney Page 33 The University of Sydney Page 34  Bending Moments near the Tower (Static Analysis) The University of Sydney Page 35  Bending Moments near the Tower (Dynamic Analysis) The University of Sydney Page 36  Axial Stresses in the Truss (Static Analysis) The University of Sydney Page 37  Axial Stresses in the Truss (Dynamic Analysis) The University of Sydney Page 38  Golden Gate Bridge – The Golden Gate Bridge is a 6 lane suspension bridge that crosses the Golden Gate Channel, connecting the San Francisco Peninsula to Marin County. After its conception in 1916, the bridges construction was a controversial issue, and the final decision to proceed with construction was not passed until 1930. (Golden Gate Bridge Research Library, May 2012) The bridge was opened in 1937 and held the title for being the longest main span suspension bridge for 27 years. (Golden Gate Bridge Research Library, May 2012) The 2332m long catenary cables are the longest bridge cables ever made. These cables used an innovative process to bind thinner wires together to make one large cable which allowed for the construction of the record breaking main span. (Longsworth, L., Loeterman, B., 2004) The bridge crosses the 1.6km wide channel which is well known for having high winds and it is situated adjacent to the San Andreas Fault line, a very active transverse fault. (Golden Gate Bridge Research Library, May 2012) The Golden Gate Bridge is one of the world’s most spectacular and well known bridges. Having been declared one of the wonders of the modern world by the American society of Civil engineers, this bridge provided a very interesting case study for this investigation. (Golden Gate Bridge Research Library, May 2012) The analysis focused on the main span of the bridge as it was the most complex part of the bridge, and was a ground breaking structural engineering feat at the time of construction. The University of Sydney Page 39  Golden Gate Bridge The University of Sydney Page 40  Truss system below bridge deck in reality and simplified for Strand7 model. The University of Sydney Page 41 The University of Sydney Page 42  Analysis of the Anzac Bridge The University of Sydney Page 43  Anzac bridge – The Anzac bridge is an 8-lane cable-stayed bridge as shown in figure 1. It spans across the Johnstons Bay that provides a key link between the Sydney CBD to the suburbs to the inner west of Sydney. It was opened in December 1995 and the total cost for the bridge was around $170million. The Anzac Bridge was designed to replace the adjacent old Glebe Island Bridge which is an electrically operated low-level steel swing bridge. The Anzac Bridge has a main span of 345m and a total length of over 800m (Groveoz). The bridge has two 120m high towers/pylons and support the deck by two planes of stay cables. There are 128 stay cables to support the reinforced concrete deck. Initially the stay cables were affected by vibration which then had been solved by adding thin stabilizing cables between the stay cables. The University of Sydney Page 44  Anzac bridge Deck section in (a) strand7 model and (b) the reality The University of Sydney Page 45  Anzac bridge reality in horizontal view The University of Sydney Page 46 The University of Sydney Page 47  Cable structure in (a) wire strand, (b) strands within cables, and (c)anchorage system The University of Sydney Page 48  Modelling the deck in Strand7 The University of Sydney Page 49  Modelling the pylon in Srand7 The University of Sydney Page 50  Static Wind Analysis Wind Applied to the deck of the Anzac Bridge The University of Sydney Page 51  The deflection of the deck under static wind load The University of Sydney Page 52 The University of Sydney Page 53 The University of Sydney Page 54 The University of Sydney Page 55 The University of Sydney Page 56