Failures. 1994 6 killed The Ramsgate Walkway Collapse 1964 4 people died.

FailuresFailures

1994 6 killed

The Ramsgate Walkway Collapse 1964The Ramsgate Walkway Collapse 1964

4 people died

Bearing Stub axle

Assumed position of resultant of forces on axle

Ramsgate Walkway support

The Ramsgate Walkway CollapseThe Ramsgate Walkway Collapse

The Ronan Point Collapse 1968

Code of practice used :

CP114 Structural Design of Reinforced Concrete Buildings

4 people killed

Stability and robustnessStability and robustness

Buildings of this type can be very robust

The Cleddau (Milford Haven) The Cleddau (Milford Haven) Bridge Collapse 1970 Bridge Collapse 1970

4 people died when the bridge collapsed under construction.

The diaphragm above the pier buckled causing the then cantilevering section of the deck to collapse.

The Cleddau (Milford Haven) The Cleddau (Milford Haven) Bridge Collapse 1970 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

Charles de Gaulle Airport 2004

Main reason for the collapse: lack of ductility to resist dynamic punching shear

4 deaths

Punching shear failure

Failures

Millennium Footbridge, London 2000

Synchronous lateral excitation

The Hartford Connecticut Civic Center Roof Collapse 1978

Happened at night - no deaths

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.

The Hartford Connecticut Civic Center Collapse

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

0.5 m 4.5 m

Internal hydrostatic pressure

Plan of tricell

Calculation (checking model) for shear stress in tricell wall of Sleipner Platform

Operating Conditions: Span of Wall - 4.5 m

Effective depth - 500 mm, Pressure head 67.0 m

Pressure at 67 m depth: p = gh = 1000 x 9.81 x 67 = 66x 104 N/m

= p x area = 66x 104 x 4.5 x 1.0 = 3000 x 103 NLoad on 1.0 m strip at 67 m depth: W

W

Max shear: V = W/2 = 3000 x 103 /2 = 1500 x 103 N

500

1000 Shear stress in concrete: vc = V/(bd) = 1500x103/(500x 1000) = 3 N/mm2

Maximum design shear stress (BS 8110 for unreinforced section): vc (BS8110) = 0.91 N/mm2

Sleipner Collapse

The collapse was due to the choice of an inadequate mesh of 3D 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 collapseHyatt 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.

• To date - worst structural accident in the British Isles.

77 people killled

Pier No. 5 Looking North

Lifting of windward column.

(Dundee City Council, Central Library, Photographic Collection)

THE END