Project: Inspection and Lifetime Assessment Tool for Arch Strucures

Motivation:_x000D_Arch bridges made of natural stone masonry nowadays rank among the oldest, mostly still fully employed supporting structures in road and rail infrastructure. Some of them with ages dating back far over 100 years, they represent a historically very valuable building fabric. There are in Austria's railroad network alone around 1000 arch bridges are still in operation, in whole Europe the estimated number of masonry railroad bridges amounts 70 000. The trend has developed from replacing the old masonry arch bridges by reinforced concrete structures to preserving the existing structures, for financial reasons as well as monument conservation aspects. Since those bridges usually have been projected for very different loads, assessments concerning the current bearing strength and the future utilisation are required. A recalculation with conventional calculation methods is often insufficient as results can considerably deviate from the actual load capacity due to various influencing factors. The challenge therefore is to find and prove more accurate methods to describe the actual state of such arch bridges, providing continuous spatial information of the structure._x000D__x000D_Objectives:_x000D_The oldest existing arch bridges have been designed based on experienced data. Later on, graphical methods were disposable for static proofs and approximations for the design of geometric parameters were developed based on the arch's thrust line. But most of them having been built between 1840 and 1900, they usually were designed for different loads and lack expertises concerning the material and its resistances. In the course of the recalculation of these structures, assessments concerning the bearing strength and serviceability on the basis of contemporary standards are required._x000D_A conventional recalculation of arch bridges with established calculation methods of the elasticity theory can lead to results that considerably deviate from the actual load capacity since there are many unknown influencing factors. Weak spots in the arch for example reduce the bearing capacity whereas the fill and the in-situ soil significantly contribute to the load transfer. Issues of construction – soil interaction are therefore of particular interest for arch bridges but can not be correctly detected by calculations based on as constructed drawings or inspections._x000D_Practical experience has shown that masonry arches in adequate condition hold remarkable bearing reserves due to their factors of influence and therewith mostly meet today's safety requirements. Estimating and using the structural reserve of existing bridges to their maximum potential in order to satisfy new re-quirements implies a precise assessment of the structure in question and an analysis of the rehabilitation project in order to guarantee structural safety and increase structural service life. In such assessments, non destructive testing condition surveys provide important spatial and structural information._x000D_In this project two different non-destructive condition survey methods are employed, both of them giving spatial information about the structure in question. The two systems that shall be applied are (a) Ground Penetration Radar and (b) 3D-Laser Scan._x000D_Ad (a): Ground Penetrating Radar has been used in civil engineering for more than 20 years to determine spatial and structural information such as layer thicknesses or defect mapping._x000D_It is a non-destructive method that sends electromagnetic waves into an object and records backscattered variations of radar signal in time. The use of this method aims to localize objects in a structure (e.g., reinforcements, joints, voids, delaminations) and to determine their material electromagnetic properties._x000D_Ad (b): 3D laser scanning is a technology that captures the shape of physical objects digitally, sending out a laser beam and measuring the time and density of reflected laser dots._x000D_Laser profilers are able to record a very high number of profiles (e.g. 300) per second; a question to be researched is whether the accuracy is high enough to detect e.g. local weaknesses._x000D_Another point of interest is to combine FE modelling strategies of masonry with strategies of inspection and monitoring of existing structures. Inspections enable the implementation of a damage detection, whereby damage is defined as changes in material as well as geometric properties of a structure. In connection with an appropriate monitoring system the process includes the observation of a system over time. For long term observations, the output of this process is to get periodically updated information regarding the ability of the structure to perform its interaction._x000D_The project consortium consists of three SME Ps with expert knowledge in design, COtenance and non-linear reliability assessment of engineering structures, and one scientific P dealing since several years with simulations and reliability assessment tools for engineering structures.

Acronym ILATAS (Reference Number: 5157)
Duration 01/01/2010 - 31/12/2012
Project Topic Historical and even new arch bridges all over Europe supporting road and railway structures are not designed for currently required EN-load combinations. The objective of this project is the development of a monitoring and numerical based reliability lifetime assessment device for arch structures.
Project Results
(after finalisation)
Development of a methodology to measure, simulate and assess the structural condition of arch bridges reliably. Advantages have been achieved in terms of measurement of the bridge deformation during traffic loading in order to assess structural stiffness as well as finite element simulation (material properties, model creation and interaction with measurement data). Verification tests have been performed on real structures from Austrian Federal Railways.
Network Eurostars
Call Eurostars Cut-Off 3

Project partner

Number Name Role Country
4 Aplica Advanced Solutions GmbH Coordinator Austria
4 Univ. of Natural Resources and A. L. Sc.; Dep. Struct. Eng.+Nat.Hazards.; Inst. of Civil Eng. Partner Austria
4 Schimetta Consult Partner Austria
4 Cervenka Consulting Partner Czech Republic