Federal Highway Research Institute


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Steel structures, corrosion protection, bridge equipment

Bridge ropes - Non-destructive testing methods (15.0620)
Test centres for the ropes of bridges in Germany carry out rope tests without being controlled and checked in the quality of their work. It happens that the test results on the same ropes are different. The aim of this project is to ensure that the testing methods of the various testing bodies can be objectively evaluated in comparison. Recommendations and requirements regarding the non-destructive testing of bridge ropes are to be formulated on the basis of practical rope tests for the updating of the rules and regulations (RI-ERH-ING). The introduction of clear regulations serves to standardise the tendering, performance and documentation of the tests. It can be assumed that in many cases this will contribute to simplifying the interaction between road construction authorities and contractors.

Evaluation of current design approaches for torsion with bending and shear force on the basis of national and international test results (89.0350)
The realistic determination of the shear force bearing capacity of concrete bridges has been the subject of research at both national and international level for many years. The aim of the project is the compilation and analysis of decisive parameters on the bearing capacity for torsion with bending and shear force. The design models currently used for recalculation and discussed for new construction are to be evaluated and recommendations for their application derived. Furthermore, recommendations for the planning of future experimental investigations are to be derived from the investigations. The combined loading of shear force, bending and torsion (with and without longitudinal force) represents the normal case for beam cross-sections in bridge construction. While the models for pure shear force design have been continuously refined in recent years, the approaches for determining the load-bearing capacity for torsion as well as their interaction with other stresses still show greater imprecision. The findings and recommendations of the project serve both for the further development of the models of the guideline for the recalculation of existing bridges and as a basis for the development of national parameters for the future generation of the Eurocodes for the design and construction of bridge structures made of reinforced concrete and prestressed concrete.

Investigations into the installation of the road surface on steel and composite bridges (15.0655)
During the first structural inspection after the replacement of the road surface, a disproportionately high number of damages in the bridge structure is often found in steel and composite bridges. There is an urgent suspicion that the cause of this is the temperature stress resulting from the installation of the new road surface. This problem is intensified by the development of ever more powerful machines - especially ever wider screed boards. The aim of this project is to minimise the damage that can occur as a consequece of the stresses involved in paving. As a result, a correlation between the paving parameters and the resulting stresses is to be expected. The core of the research project is a market analysis and a parameter study with final recommendations for the most compatible installation of pavements on steel and composite bridges.

Fatigue strength of bracket girders on steel composite bridges and verification of the damage hypothesis on reinforced concrete slabs under tensile and shear force load (15.0679)
Bridges with steel composite box girders and bracket girders offer considerable advantages in the new construction of large bridges. For a quick implementation, constructions with precast elements and in-situ concrete supplementation are often chosen for the deck slabs, which transfer the traffic loads according to plan in the longitudinal direction. In order to ensure robust and durable constructions, certain regulations of the Federal Ministry of Transport and Digital Infrastructure have to be observed due to the lack of normative regulations for this construction method. With the planned investigations, parts of these regulations are to be examined and scientifically validated. The focus is on the fatigue strength of reinforced concrete slabs of composite bridges subjected to longitudinal tensile loads, taking shear force transfer into account. With the help of static reference and dynamic multi-stage tests, it is to be checked whether the damage hypothesis according to Palmgren-Miner is also valid for cracked reinforced concrete slabs. A further area of investigation is the connections of the bracket girders to the main girder webs of the box girder, with the aim of optimising these connections with regard to fabrication and sufficient safe fatigue strength. In addition, the aforementioned investigations are to be supplemented with the help of structural monitoring on currently executed structures.

Building Information Modeling (BIM) for bridge construction (15.0622)
The BMVI's ’Road Map for Digital Design and Construction’ establishes Building Information Modeling (BIM) as the new standard application for new planned transport infrastructure projects by 2020. The aim of this project is the development and elaboration of a practical concept for the implementation of the BIM methodology in the operational phase. Furthermore, the research project will investigate how maintenance management based on digital high-quality data can look like, what opportunities it offers and what further developments are necessary for this systematic maintenance management.

Reinforcement of the cover plate on orthotropic carriageway slabs by affixing steel sheets – construction details (2217004)
As a rule, bridges are designed for a service life of around 100 years. Numerous steel bridges built in the 1960s therefore currently have about half of their originally intended lifespan behind them. Over the past 25 years, however, consistent increases to damage in local load application areas have been recorded, and these repeatedly give rise to expensive and complex repair measures. In many cases a replacement construction will foreseeably be required before the originally intended service life has been reached. Due to the usual building regulations in Germany it can take several years before construction work can begin. Therefore the operation of the existing bridge must be maintained as far as possible until the replacement construction has been opened to traffic. Repairs conducted in the past often proved in retrospect to be expensive, pointless measures. Effective concepts and new solutions for repairing steel bridges are therefore needed. By affixing steel sheets to reinforce the cover plate on the orthotropic carriageway slabs, the idea is to pursue and closely examine a very particular, yet promising, solution. The objective of a number of projects is to demonstrate the practical suitability of adhesives and bonded joints for the reinforcement of the cover plate on orthotropic carriageway slabs, thereby creating a foundation for new solutions in terms of repairs to steel bridges. The focus within the “Construction details” project is on the arrangement of joints and the design of edge finishing. Tests are carried out using realistic swelling tests and fatigue bend tests.

Replacement of the road surface on steel bridges (2216012)
The use of ever larger construction machines has greatly changed the processes of replacing road surfaces on bridges in recent decades. On the one hand, it has been possible to reduce the time required considerably. On the other hand, this is associated with a greater burden which can lead to damage in the orthotropic deck particularly in older steel bridges. In order to obtain an overview of the current state of the art and assess its impact, corresponding construction projects are to be accompanied at a technical and measurement level. Based on the results, limits are to be defined and recommendations made in order to avoid future damage attributable to incorrect execution in the replacement of surfaces.

Capacity of bridge structures to adjust to altered conditions of use – conceptual optimisation approaches (15.0624)
Adjustments required for foreseeable or conceivable future changes in the use of bridge structures impact the substance of a structure built with the usual method of infrastructure construction. They cannot be implemented in the existing structures and require new builds. Analyses of possible changes in use in the future and their impacts on bridges have so far been available neither for typical road bridges nor for other transport systems. In future it will be necessary to develop possibilities of considering these later changes in use at the planning stage and in the construction of concrete, steel and composite bridges such that they can be facilitated cost effectively with as little impact on traffic as possible. The aim of the project is to develop new concepts which permit bridge structures to be flexibly adapted to altered conditions during their serviceable life and during traffic operations. Furthermore, changes in framework conditions should not make it necessary to replace bridges.

Network of experts: changed conditions of use – adaptation of bridge structures (2216000)
On average, road, rail and waterway infrastructures are old, which means there is an increasing level of damage which in its turn is associated with possible restrictions in terms of availability of installations. These effects are frequently compounded by predictable or conceivable future changes of use, with increases in the traffic and fatigue loads and the need to expand capacity. With the usual method of infrastructure construction, this may lead to substantial interventions in the structure or it may even be impossible to alter the existing infrastructure. Typical changes of use for structures deployed in the various modes of transport are to be analysed in the project. It is to be examined how these subsequent changes of use can be considered when planning new structures so that they may be made inexpensively and with the least possible traffic interference. Predictable or conceivable future changes of use for typical road, rail and waterway structures are to be quantified, bridge structures analysed in terms of actual capacity and use, and impact and requirements determined with regard to load-bearing capacity and fitness for use.

Recalculation of existing steel and composite bridges – remaining use (15.0529)
Due to the sharp increase of heavy traffic over the course of recent decades and the forecasted continued increase, existing steel and composite road bridges must be evaluated in terms of their pure load-bearing capacity as well as in terms of their remaining useful life. Benefits of such an evaluation include the provision of an important decision-making basis regarding the practicality of further investments: (emergency) maintenance, strengthening or new replacement construction. In addition to verifications concerning the load-bearing capacity and fitness for use, an evaluation of the remaining useful life also includes verifications concerning fatigue. The "Guideline for the Recalculation of Existing Road Bridges (Recalculation Guideline) Edition 05/11)" represents a tool that is now available in order to ensure a Federal-wide implementation. Within the context of the research project, the intention is to apply the regulations of the recalculation guidelines to respectively suitable, existing steel and composite bridges. The objective is to formulate adjustments, supplements and needs for improvement for the recalculation guideline as well as to identify further needs for research. Recommendation and advice will be developed for users on how to proceed during the calculation-based determination of the remaining useful life and in order to determine suitable operating time intervals when dealing with steel and compound bridges as part of roads.