Computer modelling of bridge deck cracking at early ages

Title: Computer modelling of bridge deck cracking at early ages
Author(s): Lianfang Li, Neal S. Berke
Paper category : conference
Book title: 2nd International RILEM Symposium on Advances in Concrete through Science and Engineering
Editor(s): J. Marchand, B. Bissonnette, R. Gagné, M. Jolin and F. Paradis
Print-ISBN: 2-35158-003-6
e-ISBN: 2351580028
Publisher: RILEM Publications SARL
Publication year: 2006
Nb references: 28
Language: English

Abstract: Early age cracking of concrete bridge decks is one of the major problems for most DOTs. This type of cracking is a big concern for the durability of bridge superstructures, especially in North America, where de-icing salts are used extensively in winter times. Cracking damage in bridge decks provides a shortcut for moisture and chloride penetration and hence accelerates reinforcing steel corrosion. Therefore, mitigation of bridge deck cracking tendency is critical to its future durability performance.
In this paper, a 2-D finite element model was employed to assess the cracking risks of a 230 mm (9 in) thick concrete bridge deck within 180 days of its placement. The base model considered a 230 mm (9 in) thick reinforced concrete deck simply supported upon a structural steel girder or a precast/prestressed (PC/PS) concrete girder with a span of 36.6 m (120 ft) and a girder-to-girder spacing of 3 m (10 ft). As for the deck, six types of concretes (w/c = 0.30, 0.40, and 0.50, with and without shrinkage-reducing admixtures (SRA)) are evaluated for cracking tendency. It was found that, the usage of SRA is highly efficient in reducing cracking risks. The bridge design, especially the relative deck-to-girder stiffness also significantly affects the cracking tendency. The model predicts that adding 7.5 L/m3 SRA into concrete is able to lower the deck cracking risk by two categories, based on the concrete stress-to-strength ratio. Recent field experience in using SRA in bridge decks also strongly supports the computation results.

Keywords: Bridge Deck, Cracking, Modelling, Shrinkage, Creep, SRA, Girder

Online publication: 2006-08-02
Classification: 3.1 Theme 1: Numerical Models: from Microstructure to Transport Properties and Durability
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2351580028.031