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During a proof load test, we study the formation and growth of cracks as well as the deflections under the applied loads. Crack formation is followed with acoustic emissions measurements. Since these measurements need three cycles of loading to the same load level, they control the load process in the field.

The Ruytenschildt Bridge was a special case. This bridge was schedule for demolition, so instead of carrying out a proof loading test, we were able to load the bridge until failure. It’s a five-span reinforced concrete slab bridge, and we could test to failure in two spans.

To split up the bridge in two parts, a saw cut was made, splitting the bridge up into two independent parts. We tested the 7,365m wide part that was going to be demolished first.

Another effect that we know from testing slabs in shear in the lab is that the Eurocode shear prediction on average is too conservative. The average tested to predicted ratio for slabs under concentrated loads close to supports failing in shear is 2,023. However, this value is again determined for straight slabs. For skewed slabs, we know that the stress concentrations are larger at the obtuse corner. Perhaps this means that the increase for skewed slabs is not as large as for straight slabs and that in skewed slabs less tranverse redistribution can take place.

What you see in this table are the maximum values of the load on the loading tandem to get a shear failure. Given the uncertainties about the calculation for skewed slabs, we can give a range of values in between which we expect the shear failure to lie.

Since the material properties that were determined before the test had resulted in lower values, the maximum amount of load that was available for the test was 300 ton. We reached a maximum load of 3049 kN, and we could observe flexural distress, but failure was not achieved.

For the second test, we ordered 100 tons more of counterweights.

In span 2, where we achieved failure, we saw that flexure was the governing failure mode.

An interesting observation here as well is that we saw that for shear, we need further research on skewed slabs to identify the effective width for shear on skewed slabs, and that we need experiments to identify the transverse load redistribution capacity of skewed slabs.

We learned about the two tests on the Ruytenschildt Bridge, and the measurements we used.

We focused on the shear and moment capacity of the bridge. For the moment capacity, we saw the need to have extensive material research prior to the test, since the results of a limited number of concrete cores gave a too low value of the compressive strenght. For the shear capacity, we saw the difficulty in estimating the shear capacity of skewed slabs.

Finally, we saw that in span 1, there was flexural distress but we did not reach a failure, and that in span 2, we achieved a flexural failure of the slab, combined with settlement of the substructure.

- 1. Challenge the future Delft University of Technology Shear and Moment Capacity of the Ruytenschildt Bridge Eva Lantsoght, Cor van der Veen, Ane de Boer, Karen Flores
- 2. 2 Overview • Introduction to case • Prediction of capacity • Test results • Discussion • Summary & Conclusions Slab shear experiments, TU Delft
- 3. 3 Proof loading Case Ruytenschildt Bridge • Proof loading to assess capacity of existing bridge • ASR affected bridges • Insufficient information • Study cracks and deformations for applied loads • Crack formation: acoustic emissions measurements • Control load process • Ruytenschildt Bridge: testing to failure in 2 spans
- 4. 4 Proofloading Ruytenschildt Bridge Existing bridge Partial demolition and building new bridge
- 5. 5 Cross-sections Ruytenschildt Bridge • Testing in span 1 and span 2 • close to end support • close to mid support • Critical position for shear
- 6. 6 Predicted bending moment capacity Flexural capacity Span 1 Span 2, support Span 2, span Mcr (kNm) 1816 1690 1592 My (kNm) 3925 5662 3717 Mu (kNm) 4964 7064 4705 Corresponding tandem load Pcr (kN) 880 1278 1460 Py (kN) 2368 7720 3532 Pu (kN) 3102 9940 4496 Moment at cracking, yielding, and ultimate + corresponding tandem load
- 7. 7 Predicted shear capacity 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 • Effective width for skewed viaducts? • Slab factor of 2.023 from slab shear experiments
- 8. 8 Proofloading Case Ruytenschildt Bridge
- 9. 9 Test results proofloading Span 1 • Maximum load 3049 kN • Maximum available load for span 1 • Flexural cracks • No failure • Order additional load for test 2!
- 10. 10 Test results proofloading 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 0 500 1000 1500 2000 2500 3000 3500 4000 4500 0 2000 4000 6000 8000 10000 Load(kN) Time(s)
- 11. 11 Discussion • Loads larger than estimated capacities prior to test • uncertainties about material properties • Flexure as governing failure mode • Shear: further research on skewed slabs is necessary
- 12. 12 Conclusions • Ruytenschildt Bridge • Testing to failure in 2 spans • Measurements • Shear and moment capacity determined • moment capacity: need for material parameters • shear capacity: effective width for skewed slabs? • Observed failure mode: flexure
- 13. 13 Contact: Eva Lantsoght E.O.L.Lantsoght@tudelft.nl +31(0)152787449

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