Near-surface effects for a soft rock site (average shear-wave velocity of the top 30 m, Vs 30 ≈ 8... more Near-surface effects for a soft rock site (average shear-wave velocity of the top 30 m, Vs 30 ≈ 800 m/s) for a proposed nuclear power station in the UK are integrated into the "bedrock" results of a probabilistic seismic hazard analysis (PSHA) by application of US Nuclear Regulatory Commission (USNRC) Approach 3 and employing a partially nonergodic PSHA. The sensitivity of the surface hazard to the site response analysis method is assessed, employing both random vibration theory (RVT) and time series (TS) approaches. The effects of different assumptions relating to strong-motion duration, selection of target frequency in the surface uniform hazard spectrum (UHS) and the incorporation of the variability of site properties through Monte Carlo simulations are also quantified. The results show that for the examined stiff site, with response concentrated at high frequencies, the use of RVT site response analysis does not introduce a systematic bias in the low frequency ground motion predictions and the duration used in the definition of the input ground motions is demonstrated to have a secondary effect on the site response. The incorporation of the variability of site properties and the selection of the target frequencies in the convolution are shown to be important in the derivation of the uniform hazard spectrum.
Earthquakes can cause extensive damage to buried water supply pipelines, resulting in major finan... more Earthquakes can cause extensive damage to buried water supply pipelines, resulting in major financial losses for water utility operators and lengthy disruption of an essential service for whole communities. This thesis focuses on the behaviour of buried water supply pipelines subject to earthquake effects; particularly the transient ground strains caused by the passage of seismic waves. Existing empirical relations for the prediction of earthquake-induced pipeline damage are reviewed, with specific emphasis on identifying the reliability of the datasets used. Improvements are made to an existing dataset and areas of uncertainty in the characterisation of the seismic action highlighted. New predictive relationships are derived for strong-motion peaks from a substantial database of strong-motion records obtained from fifty-one significant European earthquakes. The sensitivity of each dataset to the record processing technique is investigated. The peak ground velocity estimations are particularly useful for prediction of earthquake-induced pipeline damage rates. Results are presented of a post-earthquake investigation into water pipeline damage in the town of Düzce, Turkey, caused by the Kocaeli and Düzce earthquakes in 1999. Temporal variations in pipeline repair statistics before and after the earthquakes are analysed to identify earthquake-related pipe breaks. In the absence of detailed geological data, site conditions in Düzce are characterised using microtremor measurements. GIS-based analysis reveals no clear correlations between spatial distributions of pipeline damage and site characteristics. A reasonable correlation is observed between pipeline damage and building damage. The spatial variation in pipeline damage rates as a result of the Kocaeli earthquake is used to infer the spatial distribution of peak ground velocity based on an existing pipeline fragility relationship. Interpretation of pipeline damage rates caused by the Düzce earthquake is obscured by the effects of the earlier Kocaeli earthquake. I have enjoyed my time based at Imperial College and have benefited much from discussions with various members of the academic staff and fellow students. In particular, I am grateful to Dr Sarada Sarma and Dr John Douglas and to other fellow members of the Soil Mechanics Research Group. On the WRc side, I would like to thank Dr Dave Marlow and Hitoshi Inada for their help with the field-work in Turkey and all subsequent assistance. Staff in the GIS Section were responsible for digitising several large maps for the Düzce case study -for which I am very grateful. Dr Ian
The Strood and Higham Railway Tunnel is some 3.7km in length and was originally built as a canal ... more The Strood and Higham Railway Tunnel is some 3.7km in length and was originally built as a canal tunnel enabling boats to pass freely between the river Medway and the river Thames. The tunnel was excavated between 1819 and 1824 through reasonably competent Seaford Chalk such that many sections were left unlined. In 1830, a 100m long section was opened out in cutting as a passing basin for the canal boats before in 1844 a single track railway was added to the tunnel. Finally in 1846, the canal was infilled to permit a double railway track to be built. Over the years, the operating railway has suffered disruption because of flooding, problems associated with old shafts and from chalk falls in unlined sections of the tunnel, one of which in December 1999 caused derailment of four railway carriages. Six months later one of the original construction shafts collapsed and the tunnel was closed for four weeks, re-opening only after a 30km/hour speed restriction was applied. This was clearly...
Earthquakes can cause extensive damage to buried water supply pipelines, resulting in major finan... more Earthquakes can cause extensive damage to buried water supply pipelines, resulting in major financial losses for water utility operators and lengthy disruption of an essential service for whole communities. This thesis focuses on the behaviour of buried water supply pipelines subject to earthquake effects; particularly the transient ground strains caused by the passage of seismic waves. Existing empirical relations for the prediction of earthquake-induced pipeline damage are reviewed, with specific emphasis on identifying the reliability of the datasets used. Improvements are made to an existing dataset and areas of uncertainty in the characterisation of the seismic action highlighted. New predictive relationships are derived for strong-motion peaks from a substantial database of strong-motion records obtained from fifty-one significant European earthquakes. The sensitivity of each dataset to the record processing technique is investigated. The peak ground velocity estimations are particularly useful for prediction of earthquake-induced pipeline damage rates. Results are presented of a post-earthquake investigation into water pipeline damage in the town of Düzce, Turkey, caused by the Kocaeli and Düzce earthquakes in 1999. Temporal variations in pipeline repair statistics before and after the earthquakes are analysed to identify earthquake-related pipe breaks. In the absence of detailed geological data, site conditions in Düzce are characterised using microtremor measurements. GIS-based analysis reveals no clear correlations between spatial distributions of pipeline damage and site characteristics. A reasonable correlation is observed between pipeline damage and building damage. The spatial variation in pipeline damage rates as a result of the Kocaeli earthquake is used to infer the spatial distribution of peak ground velocity based on an existing pipeline fragility relationship. Interpretation of pipeline damage rates caused by the Düzce earthquake is obscured by the effects of the earlier Kocaeli earthquake. work on such an interesting project, for his continued direction and support, and for his patient endurance, especially in the closing stages of the thesis. I have enjoyed my time based at Imperial College and have benefited much from discussions with various members of the academic staff and fellow students. In particular, I am grateful to Dr Sarada Sarma and Dr John Douglas and to other fellow members of the Soil Mechanics Research Group. On the WRc side, I would like to thank Dr Dave Marlow and Hitoshi Inada for their help with the fieldwork in Turkey and all subsequent assistance. Staff in the GIS Section were responsible for digitising several large maps for the Düzce case study-for which I am very grateful.
The Strood and Higham Railway Tunnel is some 3.7km in length and was originally built as a canal ... more The Strood and Higham Railway Tunnel is some 3.7km in length and was originally built as a canal tunnel enabling boats to pass freely between the river Medway and the river Thames. The tunnel was excavated between 1819 and 1824 through reasonably competent Seaford Chalk such that many sections were left unlined. In 1830, a 100m long section was opened out in cutting as a passing basin for the canal boats before in 1844 a single track railway was added to the tunnel. Finally in 1846, the canal was infilled to permit a double railway track to be built. Over the years, the operating railway has suffered disruption because of flooding, problems associated with old shafts and from chalk falls in unlined sections of the tunnel, one of which in December 1999 caused derailment of four railway carriages. Six months later one of the original construction shafts collapsed and the tunnel was closed for four weeks, re-opening only after a 30km/hour speed restriction was applied. This was clearly...
This article presents a streamlined approach to seismic hazard assessment aimed at providing regu... more This article presents a streamlined approach to seismic hazard assessment aimed at providing regulatory assurance, whilst acknowledging commercial and program constraints associated with the development of safety-critical facilities. The approach was developed based on international best practice and followed the spirit of the Senior Seismic Hazard Analysis Committee (SSHAC) Level 2 requirements, while incorporating the key features of the SSHAC Level 3 process aimed at achieving regulatory assurance, but with a more flexible implementation. It has also benefited from experience gained by others regarding the implementation of the SSHAC process in projects in the USA, Switzerland and South Africa. The approach has been successfully applied as part of the Safety Case for the new-build nuclear power plant at Hinkley Point, UK. The proposed approach can be considered as a cost-effective solution for the seismic hazard evaluation of safety-significant facilities where a high level of regulatory assurance is required.
This article presents a streamlined approach to seismic hazard assessment aimed at providing regu... more This article presents a streamlined approach to seismic hazard assessment aimed at providing regulatory assurance, whilst acknowledging commercial and program constraints associated with the development of safety-critical facilities. The approach was developed based on international best practice and followed the spirit of the Senior Seismic Hazard Analysis Committee (SSHAC) Level 2 requirements, while incorporating the key features of the SSHAC Level 3 process aimed at achieving regulatory assurance, but with a more flexible implementation. It has also benefited from experience gained by others regarding the implementation of the SSHAC process in projects in the USA, Switzerland and South Africa. The approach has been successfully applied as part of the Safety Case for the new-build nuclear power plant at Hinkley Point, UK. The proposed approach can be considered as a cost-effective solution for the seismic hazard evaluation of safety-significant facilities where a high level of regulatory assurance is required.
... Authors: Bird, Juliet. Imperial College London. O'Rourke, Thomas D. Cornell ... more ... Authors: Bird, Juliet. Imperial College London. O'Rourke, Thomas D. Cornell University. Bracegirdle, Tony. Bommer, Julian J. ... Corporate Authors: Thomas Telford Limited. Thomas Telford House, 1 Heron Quay London E14 4JD England. Editors: Mike Sweeney. British Petroleum. ...
Results are presented of an investigation into water pipeline damage in Düzce, Turkey, following ... more Results are presented of an investigation into water pipeline damage in Düzce, Turkey, following the 1999 Kocaeli and Düzce earthquakes. Temporal variations in pipeline repairs are analysed to identify earthquake-related pipe breaks. GIS-based analysis reveals no clear correlations between spatial distributions of pipeline damage and site conditions, as characterised by microtremor measurements. A reasonable correlation is observed between pipeline damage and building damage. The spatial distribution of peak ground velocity during the Kocaeli earthquake is approximated using pipeline damage data. Interpretation of pipeline damage caused by the Düzce earthquake is obscured by the effects of the earlier Kocaeli earthquake.
The major hazard posed by earthquakes is often thought to be due to moderate to large magnitude e... more The major hazard posed by earthquakes is often thought to be due to moderate to large magnitude events. However, there have been many cases where earthquakes of moderate and even small magnitude have caused very significant destruction when they have coincided with population centres. Even though the area of intense ground shaking caused by such events is generally small, the epicentral motions can be severe enough to cause damage even in well-engineered structures. Two issues are addressed here, the first being the identification of the minimum earthquake magnitude likely to cause damage to engineered structures and the limits of the near-field for small-to-moderate magnitude earthquakes. The second issue addressed is whether features of near-field ground motions such as directivity, which can significantly enhance the destructive potential, occur in small-to-moderate magnitude events. The accelerograms from the 1986 San Salvador (El Salvador) earthquake indicate that it may be unconservative to assume that near-field directivity effects only need to be considered for earthquakes of moment magnitude M 6.5 and greater.
Near-surface effects for a soft rock site (average shear-wave velocity of the top 30 m, Vs 30 ≈ 8... more Near-surface effects for a soft rock site (average shear-wave velocity of the top 30 m, Vs 30 ≈ 800 m/s) for a proposed nuclear power station in the UK are integrated into the "bedrock" results of a probabilistic seismic hazard analysis (PSHA) by application of US Nuclear Regulatory Commission (USNRC) Approach 3 and employing a partially nonergodic PSHA. The sensitivity of the surface hazard to the site response analysis method is assessed, employing both random vibration theory (RVT) and time series (TS) approaches. The effects of different assumptions relating to strong-motion duration, selection of target frequency in the surface uniform hazard spectrum (UHS) and the incorporation of the variability of site properties through Monte Carlo simulations are also quantified. The results show that for the examined stiff site, with response concentrated at high frequencies, the use of RVT site response analysis does not introduce a systematic bias in the low frequency ground motion predictions and the duration used in the definition of the input ground motions is demonstrated to have a secondary effect on the site response. The incorporation of the variability of site properties and the selection of the target frequencies in the convolution are shown to be important in the derivation of the uniform hazard spectrum.
Earthquakes can cause extensive damage to buried water supply pipelines, resulting in major finan... more Earthquakes can cause extensive damage to buried water supply pipelines, resulting in major financial losses for water utility operators and lengthy disruption of an essential service for whole communities. This thesis focuses on the behaviour of buried water supply pipelines subject to earthquake effects; particularly the transient ground strains caused by the passage of seismic waves. Existing empirical relations for the prediction of earthquake-induced pipeline damage are reviewed, with specific emphasis on identifying the reliability of the datasets used. Improvements are made to an existing dataset and areas of uncertainty in the characterisation of the seismic action highlighted. New predictive relationships are derived for strong-motion peaks from a substantial database of strong-motion records obtained from fifty-one significant European earthquakes. The sensitivity of each dataset to the record processing technique is investigated. The peak ground velocity estimations are particularly useful for prediction of earthquake-induced pipeline damage rates. Results are presented of a post-earthquake investigation into water pipeline damage in the town of Düzce, Turkey, caused by the Kocaeli and Düzce earthquakes in 1999. Temporal variations in pipeline repair statistics before and after the earthquakes are analysed to identify earthquake-related pipe breaks. In the absence of detailed geological data, site conditions in Düzce are characterised using microtremor measurements. GIS-based analysis reveals no clear correlations between spatial distributions of pipeline damage and site characteristics. A reasonable correlation is observed between pipeline damage and building damage. The spatial variation in pipeline damage rates as a result of the Kocaeli earthquake is used to infer the spatial distribution of peak ground velocity based on an existing pipeline fragility relationship. Interpretation of pipeline damage rates caused by the Düzce earthquake is obscured by the effects of the earlier Kocaeli earthquake. I have enjoyed my time based at Imperial College and have benefited much from discussions with various members of the academic staff and fellow students. In particular, I am grateful to Dr Sarada Sarma and Dr John Douglas and to other fellow members of the Soil Mechanics Research Group. On the WRc side, I would like to thank Dr Dave Marlow and Hitoshi Inada for their help with the field-work in Turkey and all subsequent assistance. Staff in the GIS Section were responsible for digitising several large maps for the Düzce case study -for which I am very grateful. Dr Ian
The Strood and Higham Railway Tunnel is some 3.7km in length and was originally built as a canal ... more The Strood and Higham Railway Tunnel is some 3.7km in length and was originally built as a canal tunnel enabling boats to pass freely between the river Medway and the river Thames. The tunnel was excavated between 1819 and 1824 through reasonably competent Seaford Chalk such that many sections were left unlined. In 1830, a 100m long section was opened out in cutting as a passing basin for the canal boats before in 1844 a single track railway was added to the tunnel. Finally in 1846, the canal was infilled to permit a double railway track to be built. Over the years, the operating railway has suffered disruption because of flooding, problems associated with old shafts and from chalk falls in unlined sections of the tunnel, one of which in December 1999 caused derailment of four railway carriages. Six months later one of the original construction shafts collapsed and the tunnel was closed for four weeks, re-opening only after a 30km/hour speed restriction was applied. This was clearly...
Earthquakes can cause extensive damage to buried water supply pipelines, resulting in major finan... more Earthquakes can cause extensive damage to buried water supply pipelines, resulting in major financial losses for water utility operators and lengthy disruption of an essential service for whole communities. This thesis focuses on the behaviour of buried water supply pipelines subject to earthquake effects; particularly the transient ground strains caused by the passage of seismic waves. Existing empirical relations for the prediction of earthquake-induced pipeline damage are reviewed, with specific emphasis on identifying the reliability of the datasets used. Improvements are made to an existing dataset and areas of uncertainty in the characterisation of the seismic action highlighted. New predictive relationships are derived for strong-motion peaks from a substantial database of strong-motion records obtained from fifty-one significant European earthquakes. The sensitivity of each dataset to the record processing technique is investigated. The peak ground velocity estimations are particularly useful for prediction of earthquake-induced pipeline damage rates. Results are presented of a post-earthquake investigation into water pipeline damage in the town of Düzce, Turkey, caused by the Kocaeli and Düzce earthquakes in 1999. Temporal variations in pipeline repair statistics before and after the earthquakes are analysed to identify earthquake-related pipe breaks. In the absence of detailed geological data, site conditions in Düzce are characterised using microtremor measurements. GIS-based analysis reveals no clear correlations between spatial distributions of pipeline damage and site characteristics. A reasonable correlation is observed between pipeline damage and building damage. The spatial variation in pipeline damage rates as a result of the Kocaeli earthquake is used to infer the spatial distribution of peak ground velocity based on an existing pipeline fragility relationship. Interpretation of pipeline damage rates caused by the Düzce earthquake is obscured by the effects of the earlier Kocaeli earthquake. work on such an interesting project, for his continued direction and support, and for his patient endurance, especially in the closing stages of the thesis. I have enjoyed my time based at Imperial College and have benefited much from discussions with various members of the academic staff and fellow students. In particular, I am grateful to Dr Sarada Sarma and Dr John Douglas and to other fellow members of the Soil Mechanics Research Group. On the WRc side, I would like to thank Dr Dave Marlow and Hitoshi Inada for their help with the fieldwork in Turkey and all subsequent assistance. Staff in the GIS Section were responsible for digitising several large maps for the Düzce case study-for which I am very grateful.
The Strood and Higham Railway Tunnel is some 3.7km in length and was originally built as a canal ... more The Strood and Higham Railway Tunnel is some 3.7km in length and was originally built as a canal tunnel enabling boats to pass freely between the river Medway and the river Thames. The tunnel was excavated between 1819 and 1824 through reasonably competent Seaford Chalk such that many sections were left unlined. In 1830, a 100m long section was opened out in cutting as a passing basin for the canal boats before in 1844 a single track railway was added to the tunnel. Finally in 1846, the canal was infilled to permit a double railway track to be built. Over the years, the operating railway has suffered disruption because of flooding, problems associated with old shafts and from chalk falls in unlined sections of the tunnel, one of which in December 1999 caused derailment of four railway carriages. Six months later one of the original construction shafts collapsed and the tunnel was closed for four weeks, re-opening only after a 30km/hour speed restriction was applied. This was clearly...
This article presents a streamlined approach to seismic hazard assessment aimed at providing regu... more This article presents a streamlined approach to seismic hazard assessment aimed at providing regulatory assurance, whilst acknowledging commercial and program constraints associated with the development of safety-critical facilities. The approach was developed based on international best practice and followed the spirit of the Senior Seismic Hazard Analysis Committee (SSHAC) Level 2 requirements, while incorporating the key features of the SSHAC Level 3 process aimed at achieving regulatory assurance, but with a more flexible implementation. It has also benefited from experience gained by others regarding the implementation of the SSHAC process in projects in the USA, Switzerland and South Africa. The approach has been successfully applied as part of the Safety Case for the new-build nuclear power plant at Hinkley Point, UK. The proposed approach can be considered as a cost-effective solution for the seismic hazard evaluation of safety-significant facilities where a high level of regulatory assurance is required.
This article presents a streamlined approach to seismic hazard assessment aimed at providing regu... more This article presents a streamlined approach to seismic hazard assessment aimed at providing regulatory assurance, whilst acknowledging commercial and program constraints associated with the development of safety-critical facilities. The approach was developed based on international best practice and followed the spirit of the Senior Seismic Hazard Analysis Committee (SSHAC) Level 2 requirements, while incorporating the key features of the SSHAC Level 3 process aimed at achieving regulatory assurance, but with a more flexible implementation. It has also benefited from experience gained by others regarding the implementation of the SSHAC process in projects in the USA, Switzerland and South Africa. The approach has been successfully applied as part of the Safety Case for the new-build nuclear power plant at Hinkley Point, UK. The proposed approach can be considered as a cost-effective solution for the seismic hazard evaluation of safety-significant facilities where a high level of regulatory assurance is required.
... Authors: Bird, Juliet. Imperial College London. O'Rourke, Thomas D. Cornell ... more ... Authors: Bird, Juliet. Imperial College London. O'Rourke, Thomas D. Cornell University. Bracegirdle, Tony. Bommer, Julian J. ... Corporate Authors: Thomas Telford Limited. Thomas Telford House, 1 Heron Quay London E14 4JD England. Editors: Mike Sweeney. British Petroleum. ...
Results are presented of an investigation into water pipeline damage in Düzce, Turkey, following ... more Results are presented of an investigation into water pipeline damage in Düzce, Turkey, following the 1999 Kocaeli and Düzce earthquakes. Temporal variations in pipeline repairs are analysed to identify earthquake-related pipe breaks. GIS-based analysis reveals no clear correlations between spatial distributions of pipeline damage and site conditions, as characterised by microtremor measurements. A reasonable correlation is observed between pipeline damage and building damage. The spatial distribution of peak ground velocity during the Kocaeli earthquake is approximated using pipeline damage data. Interpretation of pipeline damage caused by the Düzce earthquake is obscured by the effects of the earlier Kocaeli earthquake.
The major hazard posed by earthquakes is often thought to be due to moderate to large magnitude e... more The major hazard posed by earthquakes is often thought to be due to moderate to large magnitude events. However, there have been many cases where earthquakes of moderate and even small magnitude have caused very significant destruction when they have coincided with population centres. Even though the area of intense ground shaking caused by such events is generally small, the epicentral motions can be severe enough to cause damage even in well-engineered structures. Two issues are addressed here, the first being the identification of the minimum earthquake magnitude likely to cause damage to engineered structures and the limits of the near-field for small-to-moderate magnitude earthquakes. The second issue addressed is whether features of near-field ground motions such as directivity, which can significantly enhance the destructive potential, occur in small-to-moderate magnitude events. The accelerograms from the 1986 San Salvador (El Salvador) earthquake indicate that it may be unconservative to assume that near-field directivity effects only need to be considered for earthquakes of moment magnitude M 6.5 and greater.
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