Abstract
Fire design of cast-in place and post-installed anchors in concrete under fire is covered by EN 1992-4, Annex D, allowing steel- and concrete-related failure modes of anchors to be calculated. This informative annex of EN 1992-4 is limited to cast-in place or mechanical anchors, whereas post-installed adhesive anchors remain out of its scope. This paper presents a study of the applicability of the more flexible resistance integration method (RIM), proposed originally for the design of the pull-out resistance of post-installed reinforcement (PIR) by Pinoteau, on bonded anchors in uncracked concrete. This method is validated from a comparison of test results obtained from two research projects conducted at CSTB and TU Kaiserslautern on bonded anchors in uncracked concrete under ISO 834-1 fire conditions. The data considered include tests conducted on anchor sizes from M8-M30 using three different adhesives (two epoxy adhesives and one cementitious mortar). Design of the pull-out resistance under fire using RIM requires numerical calculation of temperature profiles considering models of concrete and steel elements; different assumptions about modeling these elements can produce vastly different end results. Finally, recommendations for assessment procedures for bonded anchors under fire conditions are provided as entry data for design.
Highlights
IntroductionPost-installed bonded anchors are commonly used for steel to concrete connections and offer flexibility compared to other anchor types due to their range of embedment depths and relatively smaller required edge distances and spacings
This paper presents validation and parametric study of Pinoteau’s resistance integration method (RIM) for calculating the load-bearing capacity of bonded anchors in uncracked concrete under ISO 834-1 fire conditions [17]
The temperature profiles serve as input for the RIM, in which bond strength contributions of discrete segments along the embedment depth of anchors is computed during fire exposure
Summary
Post-installed bonded anchors are commonly used for steel to concrete connections and offer flexibility compared to other anchor types due to their range of embedment depths and relatively smaller required edge distances and spacings. Many bonded anchors can be designed to similar or higher strengths than most post-installed mechanical anchors at ambient temperature. Bonded anchors are sensitive to several environmental factors [3,4,5,6] To address these sensitivities, the assessment of bonded anchors in European [7] and American guidelines [8] requires tests on different anchor geometries accounting for dry and wet concrete, minimum curing time, freeze/thaw conditions, high alkalinity, sulphurous atmosphere, installation in insufficiently clean holes, installation in freezing conditions, and in-service temperatures
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