In August 2014, the Ruytenschildt Bridge, a reinforced concrete solid slab bridge (reinforced with plain bars) in the Friesland province in the Netherlands was tested until failure. One of the goals of proof loading and testing this bridge to failure, was to study the failure mode of existing slab bridges. The combination of smaller shear capacities as prescribed by the Eurocode in combination with the heavier live load models, has raised concerns with regard to a number of existing slab bridges in the Netherlands. As the shear capacity of existing bridges is under study, the results of testing an actual slab bridge until failure are used to compare to the results of testing half-scale slab specimens in the laboratory, and the conclusions resulting from those experiments. In this paper, the results of the predictions based on the first order of approximation rating procedure from the Netherlands for shear, the Quick Scan method, as well as based on predictions of the failure mode and the average predicted capacity are compared to the experimental results. The predictions show a possibility of shear failure in the second span of the bridge. The experiment showed that both spans of the bridge failed in flexure. The observed failure mode is important, as some of the results indicate that the solid slab bridges, currently under discussion with regard to their shear capacity, fail in flexure in reality. Flexural failure is considered a ductile failure compared to the brittle failure mode in case of a shear failure.

1. Challenge the future
Delft
University of
Technology
Shear capacity of the Ruytenschildt
bridge
Eva Lantsoght, Cor van der Veen, Ane de Boer

2. 2
Overview
• Ruytenschildt Bridge testing
• Prediction of shear capacity
• Comparison test and predictions
• Summary & Conclusions
Slab shear experiments, TU Delft

3. 3
Ruytenschildt Bridge (1)
• Existing reinforced concrete slab
bridge (1962)
• Test to failure in two spans
• 4 concentrated load – one tandem
• Cyclic loading protocol
• Failure only achieved in span 2

4. 4
Ruytenschildt Bridge (2)
Existing bridge Partial demolition and building new bridge

5. 5
Ruytenschildt Bridge (3)

6. 6
Test results
Span 1
• Maximum load 3049 kN
• Maximum available load for span 1
• Flexural cracks
• No failure
• Order additional load for test 2!

7. 7
Test results
Span 2
• Maximum load 3991 kN
• Large flexural cracks
• Flexural failure
• yielding of reinforcement
• Settlement of bridge pier
with 1.5cm
• Elastic recovery to 8mm

8. 8
Quick Scan shear capacity (1)
• Method for rating bridges
• Spreadsheet for rating all sections
in a span
• Changing reinforcement
• For EN 1991-2:2003 live loads
• Load factors from NEN 8700
• Skew factors
• Result = Unity Check
• Shear stress over shear capacity

9. 9
Quick Scan shear capacity (2)
• Assuming C35/45
• Max UC in span 1 = 0.88 close to support 2
• Span 1: anchorage insufficient
• Max UC in span 2 = 0.78 at x = 1.3 m
• Measured concrete compressive strength
• Max UC in span 1: 1.14 close to Support 2
• Max UC in span 2: 1.04 at x = 1.3 m
• Shear capacity insufficient at LoA I

10. 10
Shear capacity prediction (1)
• Based on average values
• To find estimate of maximum load in test
• Effective width in shear for skewed slab?
• Skewed slab: obtuse corner is governing

11. 11
Shear capacity prediction (2)
Span Span 1 Span 2
Shear
capacity
Ptot (kN) Ptot,slab (kN) Ptot (kN) Ptot,slab (kN)
bstr 3760 7606 4020 8132
bpara 3236 6546 3432 6943
bskew 4804 9718 5328 10779
• Increase in shear capacity measured in slabs: 2.023 (average
value)
• Based on straight slabs
• Valid for skewed slabs?

12. 12
Comparison tested and predicted
results
• Span 1: no failure
• Span 2
• Flexural failure
• Shear capacity?
• Predictions:
• Equal chance of shear and
flexural failure
• Ductile vs brittle failure mode
• Shear capacity of skewed slabs?

13. 13
Summary & Conclusions
• Ruytenschildt Bridge
• Existing slab bridge scheduled for
replacement
• Testing in 2 spans, failure in span 2
• Shear capacity prediction
• Quick Scan for rating
• Average prediction for test
• Effect of skew on shear capacity of slab
and effective width?
• Flexural failure, ductile failure mode

14. 14
Contact:
Eva Lantsoght
E.O.L.Lantsoght@tudelft.nl // elantsoght@usfq.edu.ec
+31(0)152787449