123

The demand for use of methods of construction risk and reliability analysis in economy has considerably increased in last decades. The methods of structural risk and reliability analysis is a cross-disciplinary engineering science area that requires the use of different parts of construction science, as well as understanding of probability, reliability and decision-making methods.

Undesirable large-amplitude vibrations and radiated noise are not only impeding the effective operation of various types of dynamic civilian and military system, but also have a negative effect on a human environment. Noise and vibration are among the most significant issues for European community citizens. The growth in public awareness and expectations of environmental performance has led industries to focus their attention on the potential impacts arising from noise and vibration of structures and how to control and reduce them.  Regarding this it is important to note the Directive 2002/49/EC of the European Parliament and of the Council relating to the assessment and management of environmental noise.

It is well known that the association of a thin polymer layer between two metallic or composite layers permits to manufacture sheet metals having a strong absorbing energy without losing stiffness and resistance properties. These sandwich sheet metals are good noise and vibration reducers. Since the discovery of the reverse effect (actuator aspect) of the piezoelectric materials, it was proved that the latter can be used either passively through electronic shunts, or actively, through a set of electronic devices (amplifiers, controllers, etc.), for structural vibration damping.

The latest developments and methodologies for structural health monitoring and damage identification might be categorized into two general types of methods: local experimental methods: acoustic or ultrasonic methods, magnetic field methods, radiography, eddy-current methods or thermal field methods; and global methods such as vibration-based damage detection methods.

Challenge of the project is to adapt the developed vibration-based damage identification tool to the use of embedded sensors within structures. In this case dynamic characteristics of a structure are obtained by means of embedded sensors from ambient vibrations of a structure during its service or from forced vibrations by means of embedded sensor/actuator. Further the developed vibration-based damage identification tool and embedded sensor technology will be used for the development of on-line structural health monitoring methods. Effective solutions for on-line structural health monitoring and damage detection can increase safety, extend serviceability, reduce maintenance costs and define reducing operating limits for structures.

The investigation of the dynamic properties is an important reliability issue that considerable affects the performance and life-time of bridge structures. The development of transport systems and transport logistic require the efficient use of surface transport and infrastructure – roads and bridges. To achieve the high degree efficiency of transportation even larger and heavy vehicles will be used. In many cases, the bridges are subjected to loads exceeding the loads specified in standards that increase the development of damages and increase the probability of structural collapse.

The society expects that the collapse of the bridges will never happen or happen very rarely, it also relies on the professional knowledge and skills of the engineers involved in bridge design and maintenance.

The project provides the examination of the vehicle and roadway interaction and to develop a mathematical model to study the dynamic behavior of the bridge, develop the method for assessment of new bridge dynamic characteristics, investigation of the vehicle weight and speed impact on the structural dynamic characteristics of bridges, development of method for assessment of existing bridge dynamic characteristic, as well development of the recommended limits of the bridge dynamic characteristics.

The development of the modern technologies and more accurate methods of structural analysis raises the risks of loses of its load carrying capacity reserves due to insufficient strength caused by errors of the human activities or natural disasters. The assessment of risks is the part of the risk management that ensures the risk analysis and evaluation of its consequences. Risk assessment for decision-makers and the responsible parties provide a better understanding of possible risks, as well as an appropriate and effective control. Usually for the evaluation of the structural safety are used the general Eurocode approach, which is proposed for all kinds of new structures.

Therefore, it is important to develop a method for the determination of the bridge safety, taking into account the potential risk scenarios, characteristic for Latvia’s traffic load, the bridge material characteristics and models of the damage development for structural elements.

Project provide approbation of theoretical probability distribution models of bridge loads in Latvia, development of method for prediction of external action combinations, development of mathematical model describing influence of building materials physical uncertainty on loadbearing capacity, development of mathematical model describing influence of geometrical uncertainty on loadbearing capacity, as well estimation of safety index defined in Eurocodes for existing bridges.

The method developed for establishing of the size and location of the area of damage by using experimentally obtained dynamic parameters, and the corresponding signal processing methods will allow to assess the safety of the bridges, buildings and technological equipment.