Seismic Damage Index Research Articles

Elastic-Plastic Seismic Behavior of Long Span Cable-Stayed Bridges

This paper investigates the elastic-plastic seismic behavior of long span cable-stayed steel bridges through the plane finite-element model. Both geometric and material nonlinearities are involved in the analysis. The geometric nonlinearities come from the stay cable sag effect, axial force-bending moment interaction, and large displacements. Material nonlinearity arises when the stiffening steel girder yields. The example bridge is a cable-stayed bridge with a central span length of 605 m. The seismic response analyses have been conducted from the deformed equilibrium configuration due to dead loads. Three strong earthquake records of the Great Hanshin earthquake of 1995 in Japan are used in the analysis. These earthquake records are input in the bridge longitudinal direction, vertical direction, and combined longitudinal and vertical directions. To evaluate the residual elastic-plastic seismic response, a new kind of seismic damage index called the maximum equivalent plastic strain ratio is proposed. The results show that the elastic-plastic effect tends to reduce the seismic response of long span cable-stayed steel bridges. The elastic and elastic-plastic seismic response behavior depends highly on the characteristics of input earthquake records. The earthquake record with the largest peak ground acceleration value does not necessarily induce the greatest elastic-plastic seismic damage.

Seismic damage indices for RC buildings: evaluation of concepts and procedures

AbstractThis review clarifies the basic concepts involved in defining seismic damage indices for reinforced concrete buildings, and critically reviews the different schemes for classifying these indices. Typical examples are given for each class of indices, with emphasis on more recent studies. The available analytical procedures for the determination of damage indices are evaluated and the associated problems discussed. A brief reference is also made to empirical procedures for damage assessment. The most commonly used damage indices are evaluated in quantitative terms, using data from very recent comparative studies. Finally, conclusions are drawn, focusing on the practical use of these indices, and some directions for future research efforts are identified.

Seismic assessment of concrete bridges using inelastic damage analysis

As increasing numbers of structures are considered as candidates for seismic retrofit, there is a need for simple and objective methods for assessing structures, for making decisions between competing structures, and for comparing different retrofit schemes. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated inelastic analysis programs and seismic damage indices, but only if these tools can be shown to be very reliable; currently they are not sufficiently widely used for engineers to have complete confidence in them. Using extensive comparisons with laboratory test results, it is shown that inelastic analysis procedures, together with damage indices, can provide accurate and robust predictions of structural capacity. Recommendations are made for the selection and calibration of damage indices appropriate for use in seismic assessment and retrofit design.

Evaluation of Seismic Damage Indices for Concrete Elements Loaded in Combined Shear and Flexure

Damage indices have the potential to play a vital role in retrofit decision-making and disaster planning in earthquake regions. However, a major limitation of existing indices is that they have been formulated and validated almost exclusively on the basis of flexural response, neglecting the importance of shear as a cause of seismic damage. In this paper, eight damage indices are evaluated by comparison with a series of single-component tests using a variety of moment to shear ratios and stirrup spacings. On the basis of these comparisons, it appears that the more sophisticated indices which attempt to take account of the damage caused by repeated cycling give no more reliable an indication of damage than simple measures such as ductility and stiffness degradation.

Seismic Damage Indices for Concrete Structures: A State-of-the-Art Review

This paper gives a review of seismic damage indices, with particular reference to their use in retrofit decision making. Damage indices aim to provide a means of quantifying numerically the damage in concrete structures sustained under earthquake loading. Indices may be defined locally, for an individual element, or globally, for a whole structure. Most local indices are cumulative in nature, reflecting the dependence of damage on both the amplitude and the number of cycles of loading. The main disadvantages of most local damage indices are the need for tuning of coefficients for a particular structural type and the lack of calibration against varying degrees of damage. Global damage indices may be calculated by taking a weighted average of the local indices throughout a structure, or by comparing the modal properties of the structure before and after (and sometimes during) the earthquake. The weighted-average indices are prone to much the same problems as the local indices. The modal indices vary widely in their level of sophistication, those capable of detecting relatively minor damage requiring the accurate determination of a large number of modes of vibration. The development and application of damage indices has until now concentrated almost exclusively on flexural modes of failure; there is a clear need to investigate the ability of the indices to represent shear damage.