Shear Reliability Analysis of Reinforced Concrete Bridges Designed to TMH7

In South Africa, road freight is a leading participant in freight transit compared to other modes of transport. This leads to increased heavy vehicle traffic and significant deterioration of road infrastructure. The Technical Manual for Highways 7 (TMH7) design code, published in 1981, is the code for the design of reinforced concrete bridges in South Africa. Its normal traffic load model (NA loading), based on the outdated BS5400 design code and 1972 traffic loads, has not been updated to account for the changes in traffic demands. Thereby, the validity of TMH7 in simulating the current traffic demands is in question. This study investigates the shear reliability performance of TMH7 using heavy vehicle weigh-in-motion (WIM) data. The study is limited to normal traffic conditions and single-span reinforced concrete bridges. Reliability analyses were performed for two case studies: First case study considered a detailed 10m and 20m T-beam bridges designed to TMH7and performed the shear reliability on the heavily loaded beam. Secondly, a generic study considering practical load ratios. For both case studies, the assessment of the WIM data defined the probabilistic characteristics of the extreme traffic load effects and was adjusted to give 50-year extreme load effects. The First Order Reliability Method (FORM) was used to determine the reliability index and was compared to the target reliability index. The results showed that TMH7 meets the target reliability requirements intended in SANS 10160-1:2019 for load ratios between 0 and 0.5 for shorter spans and 0 to 0.65 for medium spans. The findings further indicate that resistance model uncertainty dominates shear reliability analysis for the considered cases. Overall, the outcomes of this study highlighted potential deficiencies in the NA load model in catering for actual traffic conditions in short-medium span bridges on live load-dominated cases and support the SANRAL initiative to update the model for better characterization of actual traffic loads.

Grantor dc:publisher

Stellenbosch : Stellenbosch University

Year dc:date.issued

2026

Author dc:creator

• Gasa, Kwenzokuhle

Advisors dc:contributor.advisor

• Viljoen, Celeste
• Way, Andrew

Language dc:language.iso

en

Repository record dc:identifier.uri

https://scholar.sun.ac.za/handle/10019.1/136009

OAI identifier oai:identifier

oai:scholar.sun.ac.za:10019.1/136009