Structural Testing
Peter Lindsell & Associates are regularly involved in testing new and existing structures throughout the UK. Several major projects have been undertaken in Europe and the Far East. Particular projects have required a combination of live load tests, stress measurements and monitoring techniques. A complete service has been provided in each case, consisting of pre-planning, design, installation, site tests, data handling, structural analysis and detailed interpretative report.
Selected Publications
1. Lindsell P. "Structural Weakness - Real or Imaginary". Seminar on The Real Behaviour of Structures. New College, Oxford, 9 April 2010.
2. Lindsell P. "Accommodating Irresistible Forces - Stress or Strain?" Seminar on The Real Behaviour of Structures. New College, Oxford, 9April 2010.
3. Buchner SH. "The Real Behaviour of Existing Structures". Seminar on Forensic Engineering. New College, Oxford, 27 September 2000.
4. Lindsell P and Cole G. “Bridge Load Testing in Surrey”. The Structural Engineer, Vol. 76, No.5, March 1998.
5. Lindsell P. “Load Testing in Practice”. National Steering Committee Conference on Bridge Testing: Guidelines for Supplementary Load Testing. Thomas Telford Conferences, September 1997.
6. Buchner SH. “In Situ Testing Procedures”. Seminar on The Role of Load Testing in the Assessment and Repair of Bridges. New College, Oxford, April 1997.
7. Lindsell P. “Evaluation from Structural Tests”. Seminar on The Role of Load Testing in the Assessment and Repair of Bridges. New College, Oxford, April 1997.
8. Lindsell P. “Principles of Load Testing”. Seminar on Post-tensioned Concrete Bridges – Assessing the Risks. New College, Oxford, January 1995.
9. Lindsell P. “Load Testing and Residual Stress Measurements in Concrete Bridges”. Seminar on Hidden Strength – Load Testing for Bridge Assessment, Surveyor Publ., London, February 1994.
Monitoring of forces, deflections and articulation in historic suspension bridge under live loading.
Load Testing
Peter Lindsell & Associates have wide experience of load testing individual structural sections, such as beams, columns and abutment walls, in addition to complete viaducts, bridges and multi-storey car parks. Incremental live load tests have been applied to more than 100 bridge spans, constructed from cast iron, wrought iron, steel, reinforced and prestressed concrete.
A preliminary study conducted on behalf of the National Steering Committee on Load Testing of Bridges was based upon the experience gained from these tests. A one-day Seminar on the “Role of Load Testing in the Assessment and Repair of Bridges” was organised at New College, Oxford in April 1997. The test procedures developed over the last 30 years formed the initial framework for the National Guidelines for the Load Testing of Bridges subsequently published in 1998.
Selected Projects
2007 Composite pretensioned concrete floor, controlled dismantling of aircraft hangars, Heathrow.
2005 AIL abnormal loading on post-tensioned viaduct, Cumbria.
2004 Multi-Bay reinforced concrete promenade, East Sussex.
2004 Three-span reinforced concrete river bridge, Norfolk.
2001 Through-girder steel railway bridge subject to locomotive axle loading, London
2000 Three span cast iron arch bridge, Northern Ireland.
1998 Six rigid frame bridges with various skew angles up to 58 degrees, Greece.
1999 Fourteen span post-tensioned railway viaduct, Cumbria.
1999 Composite prestressed beams, rigid frame multi-storey car park, Surrey.
1998 Segmental post-tensioned bridges, Northern Ireland.
1997 Wrought iron suspension bridge, constructed in 1887, London.
1997 Twenty-two span post-tensioned river bridge, 1km in length, Pakistan.
Measurement of structural response of Rigid Frame Bridge under full live loading to German DIN Standard.
Stress Measurements
Peter Lindsell & Associates have undertaken many hundreds of residual stress measurements on a wide range of concrete structures. The original research technique was developed from extensive laboratory and field calibration trials conducted at Surrey University and in the Channel Tunnel linings while members of the Company were testing structures to determine long-term losses of prestress. Principal concrete stresses in the surface can be determined from 75 or 150mm diameter holes. Three independent strain gauge arrays are applied to the surface, so that material stresses due to differential shrinkage, thermal gradients or ASR can be distinguished from structural effects.
In situ stresses are also regularly determined in cast iron, wrought iron or steel sections, using hole diameters ranging from 1 to 3mm. Interpretation of the strain data requires considerable research experience and depends upon the availability of calibration test data for the particular material being investigated.
Selected Projects
2000 Post-tensioned concrete columns, Oxford.
1999 Statically indeterminate voided slab deck with severe thermal gradients and differential shrinkage stresses, Greece.
1998 Early form of post-tensioned concrete bridge deck, Hampshire.
1997 Simply supported 45m span post-tensioned concrete bridge deck, Pakistan.
1996 Steel plate girder footbridge, Surrey.
1995 Cast iron arches contained in 1840 river bridge, Surrey.
1995 R.C. tunnel lining constructed in 1909, Surrey.
Concrete stress measurements at mid-span of voided slab bridge deck.
Structural Monitoring
Peter Lindsell & Associates are able to provide a complete monitoring service, based upon many years of research and site testing of structures. Monitoring systems are specifically designed and installed to meet a Client’s specification. Extensive research experience is necessary is to ensure that the test data is correctly interpreted, taking into account the material and ambient conditions on site. Detailed advice is available on the design and suitability of instrumentation systems and the procedures required to enable satisfactory interpretation of the test data.
Selected Projects
2010 Remote monitoring procedures for segmental post-tensioned bridge decks, Manchester.
2008 Monitoring of fire damaged steel trusses & columns during Dismantling & Forensic Search, Warwickshire.
2008-2000 Effects of AIL abnormal loads and seasonal movements on multi-span post-tensioned concrete viaduct over 9 year period, Cumbria.
2007 Monitoring of fire damaged steel frame warehouse during Search & Rescue Operations, Warwickshire.
2005 Load effects on reinforced concrete subway during demolition of multi-span concrete bridge above, Berkshire.
2002 Differential movements between building extension and original structure, Winchester.
2001 In plane rotational movements of skew composite bridge deck due to thermal variations, East Sussex.
2001 Load transfer onto concrete columns during pre-weakening of grain silo prior to explosive demolition.
1999 Rigid frame bridges with skew spans from 25 to 48 metres, subjected to extreme thermal cycles and temperature gradients, Greece.
1997 Selective demolition of a wrought iron bridge, Bedfordshire.
1997 Temporary prop forces in strutted retaining walls, Lincolnshire.
1997 Creep deformation of 45m post-tensioned I-beams, Pakistan.
1996 Long-term prestress losses in 3-span railway bridge, Hertfordshire.
1987-81 Long-term monitoring of earth pressures and soil/structure interaction in spill-through bridge abutments, Surrey.
Automatic long-term monitoring of 3-span post-tensioned concrete railway bridge.