Transcript [PowerPoint] - University of Salford

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
Background and context
PERCENT (%)
50
BRIDGE TYPE/MATERIAL
• 40% of all European
bridges is masonry
40
30
20
10
0
CONCRETE
METALLIC
MASONRY COMPOSITE
NOT
SPECIFIED
MASONRY BRIDGE AGE
70
• 60% of masonry
bridges are over 100
years old
PERCENT (%)
60
50
40
30
20
10
0
< 20 YEARS
20-50 YEARS
50-100 YEARS
> 100 YEARS
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 multi-ring brickwork arches.
Test series
3m span arches
5m span arches
A series of 3m span arches
(2 rings)
and a series of 5m span arches
(3 rings)
under static and cyclic loading.
Loading
Dead load
Live load
Static loading
Cyclic loading
TEST RESULTS
Static loading
STATIC LOADING
3M SPAN
Four – hinge mechanism
STATIC LOADING
5M SPAN
Ring separation
TEST RESULTS
Cyclic loading
CYCLIC LOADING
3M SPAN
Ring separation
CYCLIC LOADING
3M SPAN
Collapse:
Hinging
CYCLIC LOADING
5M SPAN
Ring separation
CYCLIC LOADING
5M SPAN
Collapse
Load
(% of static load)
100
75
57%
Endurance limit (5m arch)
50
37%
Endurance limit (3m arch)
400,000
300,000
200,000
100,000
25
Number of cycles
Load
(% of static load)
100
75
57%
Endurance limit (5m arch)
50
37%
Endurance limit (3m arch)
Mortar bond (%)
400,000
300,000
200,000
100,000
25
Number of cycles
Load
(% of static load)
100
75
Endurance limit (5m arch)
50
Endurance limit (3m arch)
25
0%
50%
Mortar bond (%)
400,000
300,000
25
200,000
100,000
50
Number of cycles
Interactive S-N curve
Endurance limit (E) can be
expressed for each mode of
failure from the Interactive SN curve as a function of the
load range (R), slope (m) and
intersection (H):
E = 10H R–m
Ring separation
Four-hinge
mechanism
Stress (Log)
1E+13
1E+12
1E+11
1E+10
1E+09
1E+08
1E+07
1E+06
100000
10000
1000
100
10
1
Log (Number
of load cycles)
(Log)
of cycles
Number
An Interactive S-N (ISN) curve
can be developed for each
mode of failure for every arch.
(Log)
of ofcycles
Number
Log (Number
load cycles)
Interactive S-N CURVE
H
Log (Stress)
3M TEST
DATA
3m test
data
Slope (m)
1
10
Load (Log)
Log (Load)
100
Shear testing
Small-scale:
Large-scale:
Triplet tests
Arch sections
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.
Shear testing summary
Triplet tests
Joint shear strength
Shear strength (N/mm 2)
0.35
0.3
0.25
0.2
Trendline for static
tests
Static
Dynamic (Failure during loading)
Cyclic
Large blocks
0.15
0.1
0.05
0
100
95
90
85
80
Bonded surface area (%)
75
70
Conclusions
• Cyclic load capacity of arches is significantly lower
(by up to 60%) than static load capacity.
• Under cyclic loading multi-ring 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.