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BRIDGE REQUIREMENT: In North America there are over 1,000 masonry
arch bridges. Europe has many thousand of such structures, 40,000 in the UK alone are in continual use by highways, railways and waterways. Most are well over 100 years old and, as of January 1999, the European Commission Directive 96/58/EEC
requires all major ( trunk) road bridges to be capable of 40 tonnes (89,500) axle loading.
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ARCHTEC RESPONSE: To provide a unique bridge reinforcement system - a complete diagnostic, design and installation service, utilizing
state of the art technology and drilling methods specially designed to strengthen masonry arch bridges.
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 offers an optimum level of strengthening while causing minimal change to the appearance of the bridge. The system also offers long-term
durability, cost effectiveness and a minimal disruption to traffic. The reinforcement is provided by CINTEC and comprises stainless steel bars surrounded by an expandable mesh fabric sleeve. These structural anchors are embedded into diamond drilled
holes tangential to the arch and contained within the thickness of the barrel. |
The sleeves are then inflated under low pressure with a high performance cementitious grout, this fills the hole and partially expands into any existing voids to provide the structural
connection with the masonry. The strength of individual bridges is accurately calculated both before and after reinforcement. By using methods of structural analysis developed by engineers Gifford & Partners Ltd, utilising software provided by
Rockwell Ltd, the performance of a bridge is modelled with an advanced discrete element technique. |
This enables the forces between individual blocks both normal, and tangential, to be progressively calculated as the theoretical load is increased. In this manner, the complex non-linear behaviour of masonry, that often defeats conventional finite
element analysis, is accurately represented at a fundamental level. The method is underpinned by research conduced at TRL (the Transport Research Laboratory). |
THE TEST:
Model arch bridge constructed in brick and based on an original bridge in the UK. The arch barrel is composed of 3 brick rings, each separated by a layer of sand; there are no spandrel walls and no road surface. The test rig had steel
formers to contain the fill at the edges. |
The failure of the laboratory model was 20 tonnes. Following the highly accurate installation of Cintec anchors, the load failure point was raised to 41 tonnes. The first hinge formed at 28 tonnes; the reinforcement prevented its
formation under the load line. |
During loading to collapse only the bottom ring of bricks fell away; the reinforcement anchors were exposed and clearly indicated a retained load-bearing capacity. |
THE RESULTS:
Load Test to Failure:
Before reinforcement, the maximum
load was 20 tonnes (44,800lbs). After the insertion of CINTEC anchors, the maximum value was increased to 41 tonnes (91,840lbs) - a factor of 2.05.
See table |
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The TRL Test: A graphical comparison between the TRL unstrengthened arch and the ARCHTEC reinforced arch.
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| THE CONCLUSIONS:
A bridge with a tested un-reinforced load capacity of 20 tonnes (44,800lbs) can be upgraded to over double that capacity through the precise insertion of Cintec anchors. It is easy to install, causes minimum
disruption to users and internal services, it is cost effective (a fraction the cost of a bridge saddle). It is invisible method of strengthening and repair.
- A complete diagnostic, design and installation service utilising state-of-the-art technology and drilling methods.
- Strengthening parameters verified by testing at TRL.
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