Target reliability for new road bridges in South Africa

[摘要] Currently, there are no recommendations of target reliability for new-build road bridgestailored to developing countries. Target reliabilities in existing international literature reflectthe economic and social circumstances associated with developed countries and may not beeconomically or societally acceptable for South Africa. This research determines target reliabilityfor new-build road bridges specifically for a South African context. Economic cost optimisationand a societal risk approach are considered. Cost optimisation considers the cost of safety andconsequences of failure. The life quality index methodology is used to consider limits on targetreliability from a societal risk perspective. Additionally, the effect of structural redundancyon target reliability in bridges is investigated. Target reliabilities from cost optimisation areshown to be slightly higher than those from SANS 10160-1 and correspond with those fromISO 2394:2015. Recommendations of annual target reliability for new-build road bridges inSouth Africa are proposed – a typical value of β = 4.2 is recommended. Societal limits on targetreliability correspond with target reliability from cost optimisation for bridges with minorconsequences of failure and do not govern new-build bridges in South Africa. Target reliabilityreduces with increasing measures of bridge redundancy; a means by which to consider theeffect of structural redundancy on target reliability is also proposed.

[学科分类] 建筑学

[关键词] target reliability;bridges;cost optimisation;structural redundancy;societal risk