November 9th 2021 Webinar

Tuesday, November 9, 2021 Webinar:

Re-evaluation of Bridge Weight Restrictions via Load Rating through Field Load Testing

Presented by Ed Zhou, PhD, P.E .

Bridge Instrumentation & Evaluation Lead


Receive (1.0) PDH

12Noon - 1PM EST


Presentation Topic:

Bridge load ratings measure a bridge’s load carrying capacity for vehicular loads in addition to its self-weight. Engineering experience has indicated that conventional methods usually yield conservative bridge load ratings due to simplifications in the analysis. In many situations, rating calculations based on the conventional analysis method indicate that the bridge needs to be posted for weight limits and yet it still carries heavy vehicles without visible signs of distress. The issue becomes more pronounced for aged or deteriorated structures, or for structures lacking information on material properties or construction plans.

Bridge load rating through nondestructive field load testing is a refined method for bridge load rating and is prescribed in AASHTO’s The Manual for Bridge Evaluation (MBE). The MBE recommends two load testing procedures: diagnostic load test and proof load test. Each method offers its own advantages as appropriate to individual circumstances and can produce more accurate load ratings than the conventional analysis. Key results from a load test are live load effects (strain and defection) at critical locations due to controlled test loads of known weights and positions. Test results quantify actual live load distribution in primary load carrying members such as skewed slabs, multiple beams or trusses including the influence of support conditions. Field measurements also help assess inherent load carrying mechanisms such as unintended composite actions and participation of secondary members.

This presentation discusses field load testing for bridge load rating and weight restriction re-evaluation purposes using both the diagnostic and proof load testing methods with multiple example projects.

Speaker Biography:

Dr. Ed Zhou is AECOM’s Bridge Instrumentation & Evaluation Lead in North America, with 27 years of experience in engineering practice. He has comprehensive knowledge and experience in multiple aspects throughout the bridge life cycle including structural analysis through finite element modeling, design, inspection, load rating, problem diagnosis, non-destructive evaluation (NDE), structural health monitoring, preservation, as well as repair, retrofit, rehabilitation, and replacement design of many types of bridge structures. He is an expert in fatigue and fracture of steel bridges and served as a past Chairman of ASCE Fatigue & Fracture Committee.

Dr. Zhou is an active member of TRB Committee AKB40 ‘Testing and Evaluation of Transportation Structures’ and has played a key role in development of multiple national guidelines and standards: co-author of TRB Circular E-C257 ‘Primer for Bridge Load Testing’; expert panel member of NCHRP Project 20-05 ‘Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information’; and co-PI of NCHRP Project 12-81 ‘Evaluation of Fatigue on the Serviceability of Highway Bridges’, which updated Section 7: Fatigue Evaluation of Steel Bridges of the AASHTO Manual for Bridge Evaluation in the 2015 Interim Revisions.