Three-Dimensional Modelling of Bond in Reinforced Concrete Theoretical Model, Experiments and Applications
Doktorsavhandling, 1999

The bond mechanism between deformed bars and concrete is known to be influenced by multiple parameters, such as the strength of the surrounding structure, the occurrence of splitting cracks in the concrete and the yielding of the reinforcement. However, when reinforced concrete structures are analysed using the finite element method, it is quite common to assume that the bond stress depends solely on the slip. A new theoretical model which is especially suited for detailed three-dimensional analyses was developed. In the new model, the splitting stresses of the bond action are included; furthermore, the bond stress depends not only on the slip, but also on the radial deformation between the reinforcement bar and the concrete. In addition, this model includes the simulation of cyclic loading. Steel-encased pull-out tests subjected to reversed cyclic loading were carried out. The tangential strain in the steel tubes was measured to investigate how the splitting stresses are affected by cyclic loading. Based on the results of these tests, several improvements of the model were made. Bar pull-out tests with differing geometries and with both monotonic and cyclic loading were analysed, using the new model for the bond action, and non-linear fracture mechanics for the concrete. The results show that the model is capable of dealing with a variety of failure modes, such as pull-out failure, splitting failure, and the loss of bond when the reinforcement is yielding, as well as dealing with cyclic loading in a physically reasonable way. The new model was used in detailed three-dimensional analyses of frame corners. Until recently, splicing of the reinforcement in frame corners had not been allowed by the Swedish Road Administration. Since this had led to reinforcement detailing that was hard to realise on site, it was of interest to examine how splicing of the reinforcement affects the behaviour of the structure. Tests on frame corners subjected to closing moments were also carried out. It was found that the analyses could describe the test performance in a reasonable way. The tests and analyses showed that splicing the reinforcement in the middle of the corner has advantages over splices placed outside the bend of the reinforcement. They also indicated, in agreement with previous work, that provided the splice length is as long as required in the codes, there are no disadvantages in splicing the reinforcement within the corner of a frame subjected to closing moment.

three-dimensional analysis

splitting effects

bond

finite element analysis

reinforced concrete

pull-out tests

non-linear fracture mechanics

frame corners

splicing of reinforcement

cyclic loading

Författare

Karin Lundgren

Chalmers, Institutionen för konstruktionsteknik

A model for the bond between concrete and reinforcement

Magazine of Concrete Research,; Vol. 52(2000)p. 53-63

Artikel i vetenskaplig tidskrift

FE analyses and tests of lap splices in frame corners

Structural Concrete,; Vol. 3(2002)p. 47-57

Artikel i vetenskaplig tidskrift

Pull-out tests of steel-encased specimens subjected to reversed cyclic loading

Materials and Structures/Materiaux et Constructions,; Vol. 33(2000)p. 450-456

Artikel i vetenskaplig tidskrift

En ny modell som beskriver vidhäftningsmekanismen mellan kamstänger och betong har utvecklats. Modellen kan hantera olika brottyper, som utdragsbrott, spjälkbrott, och att vidhäftningen minskar när armeringen flyter. Den kan dessutom simulera cyklisk last på ett fysikaliskt rimligt sätt. Modellen har använts i detaljerade tredimensionella analyser av ramhörn, för att undersöka hur armeringsskarvar inom hörnområdet påverkar det strukturella uppförandet. Ramhörn har även provats. Försöken och analyserna visade att om skarvlängden är normenlig finns det inga nackdelar med att skarva armeringen inom hörnområdet i ett hörn belastat med stängande moment.

Styrkeområden

Building Futures

Ämneskategorier

Samhällsbyggnadsteknik

ISBN

91-7197-853-4

Publikation - Chalmers tekniska högskola, Institutionen för konstruktionsteknik, Betongbyggnad: 99:1

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 1549