Failures The Ramsgate Walkway Collapse 1964 1994 4

Failures

The Ramsgate Walkway Collapse 1964 1994 4 people died 6 killed

The Ramsgate Walkway Collapse

The Ronan Point Collapse 1968 4 people killed Code of practice used : CP 114 Structural Design of Reinforced Concrete Buildings

Stability and robustness Buildings of this type can be very robust

The Cleddau (Milford Haven) Bridge Collapse 1970 4 people died when the bridge collapsed under construction. The diaphragm above the pier buckled causing then cantilevering section of the deck to collapse.

The Cleddau (Milford Haven) Bridge Collapse 1970 At that time the use of finite element analysis was not well developed. Doing a shell element model with non-linear geometry and non-linear material behaviour would have been a major achievement. Nowadays it would be quite feasible and would certainly give warnings of the problem.

Failures 4 deaths Charles de Gaulle Airport 2004 Main reason for the collapse: lack of ductility to resist dynamic punching shear

Punching shear failure

Failures Millennium Footbridge, London 2000 Synchronous lateral excitation

The Hartford Connecticut Civic Center Roof Collapse 1978 Happened at night - no deaths

The Hartford Connecticut Civic Center Collapse Two major modelling errors were the main sources of this collapse. Second order effects (non-linear geometry) were important but not included in the model resulting in lower stiffness and higher internal forces than predicted.

The Hartford Connecticut Civic Center Collapse Secondly the centroidal axes of the members were not coincident at the joints. This caused significant underestimates of moments in the members.

Sleipner Platform before collapse - 1991 No deaths but very high financial loss

Sleipner - Plan

Sleipner - Mesh at Tricell

Sleipner - Detail of Mesh at Tricell Junction

Plan of tricell

Calculation (checking model) for shear stress in tricell wall of Sleipner Platform Operating Conditions: Span of Wall Effective depth - 500 mm, - 4. 5 m Pressure head 67. 0 m Pressure at 67 m depth: p = gh = 1000 x 9. 81 x 67 = 66 x 104 N/m Load on 1. 0 m strip at 67 m depth: W = p x area = 66 x 104 x 4. 5 x 1. 0 = 3000 x 103 N Max shear: V = W/2 = 3000 x 103 /2 = 1500 x 103 N Shear stress in concrete: vc = V/(bd) = 1500 x 103/(500 x 1000) = 3 N/mm 2 Maximum design shear stress (BS 8110 for unreinforced section): vc (BS 8110) = 0. 91 N/mm 2

Sleipner Collapse The collapse was due to the choice of an inadequate mesh of 3 D elements for the walls of the tricells. The estimate of shear stress in the wall was about 1/3 of a realistic value. The computational model was not valid

Hyatt Regency walkway collapse 1981 - 114 dead

Hyatt Regency Error in understanding the load path for the hangers Modelling error Fault in designer/contractor relationship Lack of robustness

The Tay Bridge Disaster 1879 • Completed in February 1878. • Longest bridge in the world at time - 2 miles.

View showing collapsed spans. 77 people killled • To date - worst structural accident in the British Isles.

Pier No. 5 Looking North Lifting of windward column. (Dundee City Council, Central Library, Photographic Collection)

THE END