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Cracking in deep beams owing to shear loading. Part 1: Experimental study and assessment.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
2008 (English)In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, Vol. 60, no 5, 371-379 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, laboratory tests to failure of ten large deep beams with I-shaped cross-sections are presented. All beams had the same geometry with a shear span-to-depth ratio of 1.25 but differed in the amount of the vertical and horizontal web reinforcement. The presented results from the measurements consist of load-deformation curves, crack widths and crack patterns and strain distribution near the supports. The ultimate loads for these beams have been calculated with two strut-and-tie models and one truss model. The first strut-and-tie model calculates the tensile contribution of both reinforcement and concrete and takes into account their influence on the principal tensile stress. The second strut-and-tie model is a modification of the first one where the stress distribution along the strut is redefined. The third method is the truss model that is incorporated in a Design Code. The truss model gave the best result for the beams with a higher reinforcement ratio that exhibited in a shear compressive failure. The diagonal tensile failure that occurred in the beams with a small amount of web reinforcement was best captured with the modified strut-and-tie model.

Place, publisher, year, edition, pages
London: Thomas Telford Ltd , 2008. Vol. 60, no 5, 371-379 p.
Keyword [en]
Beams and girders; Reinforcement; Safety factor; Stress concentration; Struts; Tensile strength; Trusses
National Category
Building Technologies
URN: urn:nbn:se:kth:diva-10144DOI: 10.1680/macr.2008.60.5.371ISI: 000255437700007ScopusID: 2-s2.0-57849156473OAI: diva2:209506

QC 20100730

Available from: 2009-03-25 Created: 2009-03-25 Last updated: 2016-05-18Bibliographically approved
In thesis
1. Predicting shear type crack initiation and growth in concrete with non-linear finite element method
Open this publication in new window or tab >>Predicting shear type crack initiation and growth in concrete with non-linear finite element method
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]


In this thesis, the possibility to numerically describing the behaviour that signifies shear type cracking in concrete is studied. Different means for describing cracking are evaluated where both methods proposed in design codes based on experiments and advanced finite element analyses with a non-linear material description are evaluated. It is shown that there is a large difference in the estimation of the crack width based on the calculation methods in design codes. The large difference occurs due to several of these methods do not account for shear friction in the crack face.

The finite element method is an important tool for analysing the non-linear behaviour caused by cracking. It is especially of importance when combined with experimental investigations for evaluating load bearing capacity or establishing the structural health. It is shown that non-linear continuum material models can successfully be used to accurately describe the shear type cracking in concrete. A method based on plasticity and damage theory was shown to provide accurate estimations of the behaviour. The methods based on fracture mechanics with or without inclusion of damage theory, overestimated the stiffness after crack initiation considerably. The rotated crack approach of these methods gave less accurate descriptions of the crack pattern and underestimated the crack widths. After verification of the material model, realistic finite element models based on plasticity and damage theory are developed to analyse the cause for cracking in two large concrete structures. The Storfinnforsen hydropower buttress dam is evaluated where the seasonal temperature variation in combination with the water pressure have resulted in cracking. With the numerical model the cause for cracking can be explained and the crack pattern found in-situ is accurately simulated. The model is verified against measurements of variation in crest displacement and crack width with close agreement. The construction process of a balanced cantilever bridge, Gröndal Bridge, is numerically simulated and a rational explanation of the cause for cracking is presented. It is shown that large stresses and micro-cracks develop in the webs during construction, especially after tensioning the continuing tendons in the bottom flange. Further loads from temperature variation cause cracking in the webs that is in close agreement with the cracking found in-situ. The effect of strengthening performed on this bridge is also evaluated where the vertical Dywidag tendons so far seem to have been successful in stopping further crack propagation.


Place, publisher, year, edition, pages
Stockholm: KTH, 2009. xiv, 43 p.
Trita-BKN. Bulletin, ISSN 1103-4270 ; 97
non-linear finte element analysis, concrete, crack width, crack propagation, shear
National Category
Building Technologies
urn:nbn:se:kth:diva-10156 (URN)
Public defence
2009-04-17, Sal F3, Lindstedtsvägen 26 (KTH), Stockholm, 10:00 (Swedish)
QC 20100730Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2011-11-09Bibliographically approved

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