Structural Damage Identification And Model Modification Research

In recent years, the damage assessment and modification of structures has drawn wide attention from various engineering fields. With the improvement of experiment conditions and the rapid development of mode analysis technique, dynamic test technique and corresponding digital signals disposing technique, structural damage identification and modification research is pushed forward rapidly. Diversity of tests methods synthetic application accelerates the steps of damage assessment, modification and nondestructive evaluation in practice. Base on the present research, the research works is explored and developed deeply for applications going step further in civil engineering.The purpose of these research works is to develop a theoretical method for the damage assessment and dynamic characteristic modification of structures after the literature' method compare analysis, which could be function only need the lower modes and incomplete measured characteristics, and this method can be used in damage identification in civil engineering. Hence exploring research works on 5 aspects have been done around the purpose. 1.Structural damage identification research using static test data and dynamic test dataThough analyzing the existing identification approaches of using modal characteristics, especially aiming at the merit and applicability, signature matching technique is settled as the theoretical basis to locate damage in the structure. The damage signature matching technique is improved through a proper discrepancy definition of measured damage data and predicted damage data, the data include static test data and dynamic test data. Then, the general relation of the change of the curvature mode shapes and element strain is derived,form this, the change of element strain and natural frequencies are employed effectively as index in the damage identification. For a definite structure, the damaged components, which have no or fairly little contribution to structural deformation under a certain load case, the effect of the damages may be concealed due to the limited load paths, will be difficult to be identified. The kind of characteristic only can be overcome by optimizing the loading scheme or adopting several groups loads synthetically. Since the lower modes and static strain data can be obtained accurately relatively for usual structures, and contrast the results data of FEM analysis, the damage identification and extents estimate can be processed.2.The dynamic method research for damage identificationThe segment studies the dynamic test method of structural damage identification, which includes the pulsating test of masonry model, inter-revising method on identifying the inherent frequencies and mode shapes. After these, the vibration reverse problem theory is applied on the parameters identification research of masonry structure. Meanwhile, remain stiffness and residual force vectors are used for damage identification and extents estimate. 3.The experiment research of masonry modelThe pseudo-static test and pulsating test experiment are performed with a three-story masonry of half scale model. The test results will be applied on damage identification and modification research. For local dynamic characteristic can meet the predetermined requirements, The experiment adopt mass addition technique for the model modification. The change of dynamic characteristics are monitored and discussed during the model is moving and pseudo-static testing period. And some important factors and law, such as the stiffness decline, strength change and damage shape are mainly discusses. Model test and analysis aregiven to demonstrate the validation of the response control and the modification method. 4. The method of dynamic characteristic modificationIn the dynamic response control and modification research of structure, a dynamic characteristic modification method of undamped system is proposed for structural optimum modification and repairing design. Base on the dynamic characteristic of an original mode...