Damage detection in sluice hoist beams subject to excitation at resonance frequency band based on local primary frequency

Cracks of sluice hoist beams due to the load and aging of the material threaten the safety of sluice structural system. As the one of the main methods of damage detection, the non-destructive detection method based on natural frequency is still insensitive to local damage. Therefore, this paper proposes a method for hoist beams damage detection driven by resonance frequency band based on local primary frequency in the local mode. Firstly, the possibility of damage detection based on local primary frequency is discussed and the procedure of determining resonance frequency band is explained. Then the damage identification index based on the change ratio of local primary frequency is provided. Finally, numerical results demonstrate the correctness and effectiveness of the proposed method. The proposed method can provide reference for damage detection of hoist beams and health monitoring of sluice structural system

Nonlinear design and monitoring aspects of jointless structures

Jointless bridges are characterized by integral abutments and their lack of bearings and expansion joints. Recently this construction type has gained much popularity among bridge owners, since reduced costs in maintenance and rehabilitation are to be expected caused by the lack of significantly endangered details like joints and bearings. However, due to uncertainties regarding numerical modeling, material strength development and interaction with the soil the acceptance by designers is not that high. Currently those topics are being addressed by a number of research projects aiming at (a) the verification of current design criteria for jointless bridges, (b) the improvement of those, and (c) the derivation of an Austrian guideline regarding the design of this construction type. By monitoring the real structural response using suitable sensor-systems and performing advanced finite-element calculations to study the influence of creep, shrinkage and loading, current design concepts are being evaluated. Finally based on those models the most relevant design criteria can be optimized even taking into account the non-linearities in material laws and geometrical properties. This paper presents a suitable concept for non-linear design which allows for the activation of reserves in bearing capacity and thus more efficient design. Modeling uncertainties as well as sensitivities between material properties, loading and design parameters are covered by the second paper “Probabilistic Design Aspects of Jointless Structures associated with Monitoring Information”

Stochastic nonlinear analysis of concrete structures - Part III : application to bridges

A complex approach to the reliability assessment of reinforced concrete structures is introduced and demonstrated on a real existing bridge structure. The paper follows the theoretical Part I of the paper and presents mainly applications. The reliability index of a structure decreases during its life cycle due to material degradation. A retrofitting to the desired reliability level should be performed. This procedure is modeled by advanced life-cycle computer simulation. The main feature of the presented approach is the nonlinear finite element analysis of the structure employed for the realistic assessment of structural behavior.Asuitable technique of statistical sampling, which allows relatively small numbers of simulations, is used in this context. Different degradation scenarios are analyzed concerning their effect on the structures reliability progression. These studies give a basis for future models including analytical deterioration models combined with in situ monitoring, used to launch the degradation process and the inverse damage detection. Finally the presented methodology for advanced life-cycle analysis will be integrated in the innovative decision-making tool that supports maintenance planning of engineering structures

SBETA computer program for nonlinear finite element analysis of reinforced conrete structures

SIGLETIB Hannover: RO 5280(1990,1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman