1. CYCLIC LOAD CAPACITY AND ENDURANCE LIMIT OF MULTI-RING MASONRY ARCHES Clive Melbourne, Adrienn Tomor Jinyan Wang School of Computing, Science and Engineering, University of Salford

2. Background and context
40% of all European bridges is masonry
60% of masonry bridges are over 100 years old

3. Background and context
Due to the increasing traffic loading the life expectancy, capacity and fatigue performance of arch bridges needs to be better understood.
Most experimental work so far has been carried out under static loading.
Ring separation failure under cyclic loading is one of the main sources of concerns as it can significantly reduce the capacity of multiring brickwork arches.

4. Test series
3m span arches
5m span arches

5. A series of 3m span arches
(2 rings)

6. and a series of 5m span arches under static and cyclic loading.
(3 rings)
under static and cyclic loading.

7. Loading
Dead load
Live load
Static loading
Cyclic loading

8. TEST RESULTS

9. STATIC LOADING 3M SPAN
Four – hinge mechanism

10. STATIC LOADING 5M SPAN
Ring separation

11. TEST RESULTS

12. CYCLIC LOADING 3M SPAN
Ring separation

13. CYCLIC LOADING 3M SPAN
COLLAPSE:
By hinging

14. CYCLIC LOADING 5M SPAN
Ring separation

16. Small increase in the load level can cause rapid failure.
(% of static load)
Number of cycles
Small increase in the load level can cause rapid failure.
Failure occurred within a relatively few number of cycles (400,000) once endurance limit was reached.
Endurance limit was reached around 37-57% of the static load capacity of fully bonded arches.
Typical failure mode was ring separation.
100 75 50 25
100,000
200,000
300,000
400,000
57%
37%
Endurance limit (5m arch)
Endurance limit (3m arch)

17. Endurance limit (3m arch) Endurance limit (5m arch)
100 75 50 25
100,000
200,000
300,000
400,000
Load
(% of static load)
Number of cycles
Endurance limit (3m arch)
Endurance limit (5m arch)
57%
37%
Mortar bond (%)

18. Endurance limit (5m arch)
Load
(% of static load)
100 75 50 25
100,000
200,000
300,000
400,000
Endurance limit (5m arch) 50 25
50% 0%
Endurance limit (3m arch)
Endurance limit
Mortar bond (%)
Number of cycles

19. Interactive S-N curve
Interactive S-N CURVE
Ring separation
4-hinge
mechanism
Number of cycles (Log)
Stress (Log)
An Interactive S-N (ISN) curve can be developed for each mode of failure for every arch.
Endurance limit (E) can be expressed for each mode of failure from the Interactive S-N curve as a function of the load range (R), slope (m) and intersection (H):
E = 10H R–m
3m test data
Slope (m) H
Number of cycles (Log)
Load (Log)
3M TEST DATA
As a practical tool an Interactive S-N (ISN) curve can be developed for each mode of failure for every arch.

20. Shear capacity of the mortar-brick bond was also investigated
Shear testing
Shear capacity of the mortar-brick bond was also investigated
Small-scale:
Triplet tests
Large-scale:
Arch sections

21. Triplet tests Mortar bond in arches is rarely perfect (100%).
Shear capacity with various extent of mortar bond was tested
under static and cyclic loading.

22. Trendline for static tests
Shear testing summary
Shear testing summary
Trendline for static tests
Exponential relationship between shear strength and the extent of mortar bond was indicated under static loading.
Significant reduction in the static shear capacity was observed for <90% bonded surface area.
Large-scale arch sections show significantly greater shear capacity compared to triplets.
Cyclic shear capacity seems to be significantly smaller than the static load capacity.

23. Conclusions
Cyclic load capacity of arches is significantly lower (up to 60%) than static load capacity.
Under cyclic loading multiring arches failed by ring separation at significantly lower loads than that associated with a four-hinge mechanism.
A model for an Interactive S-N curve for the various modes of failures was proposed for assessment of residual life and fatigue performance.
Shear capacity of the mortar bond showed strong relationship to the extent of mortar bond.

24. END

26. Finite elements analysis

27. FE analysis Longitudinal shear stresses
DL + LL DL
1st crack

28. Finite elements analysis
Currently there is not enough data available for calibrating and modelling arches under cyclic loading.
Convenient for modelling arches as a continuum, but ring separation and other modes of failures need to be investigated specifically.
Under static loading FE showed that radial cracks can locally increase the longitudinal shear stresses that can cause ring separation at a significantly lower load associated with formation of hinges.