Wilhelm Buschmeyer

Knowledge discovery in bridge monitoring data: a soft computing approach

Road and motorway traffic has increased dramatically in Europe within the last decades. Apart from a disproportionate enlargement of the total number of heavy goods vehicles, overloaded vehicles are observed frequently. The knowledge about actual traffic loads including gross vehicle weights and axle loads as well as their probability of occurrence is of particular concern for authorities to ensure durability and security of the road networks structures. The paper presents in detail an evolutionary algorithm based data mining approach to determine gross vehicle weights and vehicle velocities from bridge measurement data. The analysis of huge amounts of data is performed in time steps by considering data of a corresponding time interval. For every time interval a population of vehicle combinations is optimized. Within this optimization process knowledge gained in the preceding time interval is incorporated. In this way, continuously measured data can be analyzed and an adequate accuracy of approximation is achieved. Single vehicles are identified in measured data, which may result from one or multiple vehicles on the bridge at a given point of time.

METHODS FOR RAISING SUSTAINABLE DESIGN OF CONCRETE STRUCTURES

Structural methods to obtain solid concrete structures based on the principle of sustainability are discussed. General principles of design containing rules of planning sustainable structures with potential of remodelling are shown as well as those of rebuilding and redesigning, explained by constructed examples from the authors’ practice.

Soft-WIM: Vehicle Identification from Bridge Measurement

This paper presents an approach for the identification of operational loads given measured static responses of a bridge structure and its corresponding analytical model. In an optimization process single vehicles and corresponding attributes are identified from data recorded during the presence of one or multiple vehicles on the bridge. The vehicle attributes gross weight, velocity, axle loads and axle spacings are determined. The problem is solved by means of two encapsulated evolutionary optimization routines. The objective function is represented by the calculation of the difference between measured and computed strains. For measurement, only two sensors which are installed in one cross section without any installations on top of the bridge are required. The application to real measurements as well as obtained results will be shown. The results demonstrate that structural health monitoring in conjunction with adequate mechanisms can successfully support the acquisition of additional, valuable information.

NEW REPAIR TECHNIQUES FOR CONCRETE STRUCTURES

This paper presents two new techniques for repairing concrete structures. The first technique repairs cracks and removes textural defects, by injecting a new grout consisting of fine-graded cements with additives including flow promoters. A high-speed mixer, producing a colloidal mixture of low viscosity, is used to obtain an injectable cement grout, which is highly insensitive to concretes moisture conditions. The grout also requires sufficient long-term workability. Several tunnels have been injected, with promising results. The second technique was developed for strengthening reinforced or prestressed concrete structural elements, and uses additional reinforcement in grooves, embedded into shotcrete or, if that is not possible, into high-slump concrete with aggregate. The grooves are prepared mechanically by high-pressure water jets, which allow only minimum tolerances for the designed geometry. The additional reinforcement is placed in the sound part of the concrete cross section, and the bond characteristics of the existing concrete can be used. Up to now, two bridge superstructures have been strengthened, with impressive results.

Einleitung großer Biegebeanspruchungen in Plattentragwerke

Die konstruktive Durchbildung von Stahlbetonbauteilen ist entscheidend fur deren Tragverhalten. So mussen zur Einleitung groser Biegebeanspruchungen im Plattentragwerk spezielle Bewehrungsfuhrungen und entsprechende Modellbildungen angewandt werden. Nur durch geeignete und betongerechte Methoden zur Verankerungsverkurzung lassen sich die Beanspruchungen sicher anschliesen. Initiation of high bend loading in slab structures Explanatory notes for construction design The construction design of reinforced concrete elements is essential for the load-bearing behavior. For the initiation of high bending loads in slab structures special reinforced layouts and appropriate modeling is necessary. Only with suitable methods of anchoring reduction the loadings can be connected certainly.