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Structural design failures: Difference between revisions
Structural design failures (view source)
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[[File:Ronan-poit.png|thumb|300x300px|Figure 1 The collapse at Ronan Point ]] | [[File:Ronan-poit.png|thumb|300x300px|Figure 1 The collapse at Ronan Point ]] | ||
The 22 storey Ronan Point building in London was of ‘large panel’ construction i.e. the structure | The 22 storey Ronan Point building in London was of ‘large panel’ construction i.e. the structure consisted of large precast concrete wall and floor units with no beams or columns. In 1968, a gas explosion at the 18th storey near a corner of the building resulted in local walls being blown out. The fall of the now unsupported panels directly above the explosion then took away the corner panels below the explosion - Figure 1. Four people died. | ||
This was a wake-up call for the need to consider progressive collapse in structural design and resulted in important changes in structural design philosophy. | This was a wake-up call for the need to consider progressive collapse in structural design and resulted in important changes in structural design philosophy. | ||
A post-accident investigation into the condition of all UK high-rise large panel buildings showed that structural designers in the UK had tended to use Code of Practice ''CP114: The structural use of reinforced concrete in buildings'' for the technical assessment of large-panel buildings. Many of these designers had not asked the question: “Does CP114 address all the issues that need to be considered for the design of large-panel buildings?” The answer to that question would have been “No!”. CP114 was written mainly for cast-in-situ beam and column structures; important issues for large-panel buildings, particularly how the panels should be connected, were not addressed in the code and hence in many of the designs. The core issue was that the use of the CP114 Code of Practice was not subject to a validation analysis. The requirements for the reinforced concrete used in the building were not all | A post-accident investigation into the condition of all UK high-rise large panel buildings showed that structural designers in the UK had tended to use Code of Practice ''CP114: The structural use of reinforced concrete in buildings'' for the technical assessment of large-panel buildings. Many of these designers had not asked the question: “Does CP114 address all the issues that need to be considered for the design of large-panel buildings?” The answer to that question would have been “No!”. CP114 was written mainly for cast-in-situ beam and column structures; important issues for large-panel buildings, particularly how the panels should be connected, were not addressed in the code and hence in many of the designs. The core issue was that the use of the CP114 Code of Practice was not subject to a validation analysis. The requirements for the reinforced concrete used in the building were not all within the scope of the CP114 code. | ||
The 1968 ''[https://archive.org/download/op1268013-1001/op1268013-1001.pdf Report on the inquiry] into the collapse of flats at Ronan Point'' is model of good reporting. The collapse occurred on 16 May and the Committee first met on 30 May,1968. By the beginning of August 1968 the Report was mainly complete. No lengthy legal procedures were used. | The 1968 ''[https://archive.org/download/op1268013-1001/op1268013-1001.pdf Report on the inquiry] into the collapse of flats at Ronan Point'' is model of good reporting. The collapse occurred on 16 May and the Committee first met on 30 May,1968. By the beginning of August 1968, the Report was mainly complete. No lengthy legal procedures were used. | ||
=== The Cleddau Bridge collapse === | === The Cleddau Bridge collapse === | ||
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In 1970 a section of a steel box girder bridge intended to span the River Cleddau in Wales collapsed when under construction - Figure 2; four construction workers were killed. While there were other important factors, the analsis modelling used in the design for the structure was inadequate for prediction of the collapse. The main cause of the failure was buckling of the diaphragm at a pier. In order to predict the collapse, a shell element model with non-linear material and non-linear geometry effects should have been used. Such features were difficult to implement in 1970 as compared with the potential of modern software. | In 1970 a section of a steel box girder bridge intended to span the River Cleddau in Wales collapsed when under construction - Figure 2; four construction workers were killed. While there were other important factors, the analsis modelling used in the design for the structure was inadequate for prediction of the collapse. The main cause of the failure was buckling of the diaphragm at a pier. In order to predict the collapse, a shell element model with non-linear material and non-linear geometry effects should have been used. Such features were difficult to implement in 1970 as compared with the potential of modern software. | ||
A major issue in the behaviour of the | A major issue in the behaviour of the structure was not identified in the validation of the analysis model. | ||
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