Papers by Keyword: Damage Index

Abstract: The damage evolution equation of RPC is established based on 2-parameter Weibull distribution. The constitutive relation of RPC is then calculated based on the damage evolution equation. The constitutive model of RPC is optimized by comparing experimental constitutive curve to models corresponding to different threshold strain. Based on the definition of damage index in ABAQUS, the damaged evolution equation in ABAQUS is recalculated based on the optimized constitutive relation. the concrete damaged plasticity model in ABAQUS is obtained using the aforementioned method. And the concrete damaged plasticity model is applied to three compression member and three simply supported beams with different reinforcements. The calculated stress-strain curve and deformation of three compression member and three beams is in accordance with the deformation characteristics of experiments, which verified the effectiveness of the proposed concrete damaged plasticity model of RPC.

Abstract: Structure damage identification is a hot research area internationally in recent years. Two damage identification methods based on sensitivity analysis are concluded. A three-tier steel frame structure model is established through utilizing ANSYS10.0, the software of finite element analysis. Through modal analysis of finite element, the frequency and formation before and after damage are obtained. The position of damage of the model is fixed by applying two damage indexes. It is indicated from the results that these two methods are effective for damage identification of the space structure of steel frame.

Abstract: Existing non-seismically detailed low-rise RC buildings have higher seismic risks that are dependent on their seismic capacities and demand of building sites. Seismic risk analysis can be performed considering probabilistic characteristic of the structural damage. Structural damage is more accurately quantified by the damage indices than by a single engineering parameter. This study carries out comparative seismic risk analysis of a prototype building with and without metallic energy dissipating devices. Based on the probability distribution of damage index, it is demonstrated that the application of well-designed MEDDs to low-rise RC building can reduce its potential seismic risk.

Abstract: Mathematical model through system identification techniques is composed of the development of a variety of back Analysis solutions and signal processing technology reflecting physical damage of structures. This study was in progress divided into analysis and experimental research, and it was simulated by simplified model based on relevant theory of damage locations and damage estimates. Steel structure concerned by the vibration and impact load was researched in order to predict the dynamic behavior. The 3rd floor of one bay steel frame structure was used, because analysis of whole structure is inconvenient when analyzing and testing, and it is very hard to accurately predict actual behavior by complexity of model in case of three-dimensional structure. Natural frequency of the simulation was calculated as using ANSYS program, general-purpose finite element analysis program, and damage index was estimated through counting natural frequency when structural damage occurred in the test as using the FDD (Frequency-Domain Decomposition).

Abstract: This study investigates the influence of the in-plan structural layout on the seismic response of symmetric and asymmetric steel structures. A five-storey steel frame building was used as reference structure and two different structural systems were employed to represent torsional stiff and torsional flexible structures. Accurate numerical models of the different typologies of structures were developed and both nonlinear static and dynamic analyses under bi-directional ground motion were carried out. The influence of axial force-bending moment interaction in columns in the two main directions and second order effects were taken into account in the numerical analyses. The results of the numerical investigations on symmetric structures showed that the reduction of the number of moment resisting connections may lead to an increase of the structural damage. Asymmetric variants of the investigated structures were created by assuming different mass eccentricities in each of the two main directions and extensive parametric studies were performed. For the torsionally flexible building, the influence of ground motion intensity was very strong. A transition from torsionally flexible to torsionally stiff behaviour in the weaker direction of the initially torsionally flexible structure was observed for severe seismic actions. The change of the stiffness of the structure in one direction due to high levels of plastic deformations affected the structural response in the orthogonal direction. Torsional effects decreased in case of severe seismic excitations and high levels of plastic deformations. The reduction of torsional effects observed for low seismic actions on the stiff side of torsionally stiff buildings disappeared under strong seismic excitations.

Abstract: According to the pseudo static tests on a two-storey and single-span concrete frame made with recycled aggregates, the failure pattern, hysteresis loop curves, displacement ductility of the recycled aggregate concrete frame are investigated. The time histories of loads and displacements are decomposed to four different levels by using the wavelet packet transform. Based on the decomposition coefficients on the 4th level, a seismic damage index is developed and presented in this paper. The cumulative damage process of this recycled aggregate concrete frame under low reverse cyclic loading is also analyzed by using this damage index. The experiment results clearly indicate that recycled aggregate concrete frames have excellent seismic behaviors. The damage index given in this paper can accurately and effectively reflect the severity of damage for structures under different loading states.

Abstract: With the author and others scientific investigation on China Wenchuan Ms8.0 earthquake, China Yushu Ms7.1 earthquake and "China's active fault surveying and earthquake hazard evaluation project" relevant data results and the world requirements about project setback of active faults, etc., this paper concluded that: (1) width of Surface-Fault-Rupture is about 40m by statistics, or from the main surface rupture trace about 20m; (2) width of Surface-Fault-Rupture S and the fault vertical offset V, statistical diagrams and formulas S=8.72+9.01V; (3) Setback of the main surface trace D and buildings from damage index I, statistical diagrams and formulas I=0.7969-0.00231D; (4) based on the first three results and by the actual statistics of accuracy, we get three active fault location accuracy level of the standard i, ii, iii, respectively, the error is ± 5m, ± 25m, ± 60m, also, can give this level of standards of Surface-Fault-Rupture width to the actual engineering applications.

Abstract: To understand the higher modal effect on the accuracy of pushover analysis for shear wall structure, the influence of damage on the vibration characteristics of shear-wall structures is investigated. Employing the continuum technique, the shift of modal shapes and periods for the first three modes is obtained when the plastic zone exists in the bottom of the shear wall. It can be conclude that plastic zone may enhance the higher modal effect when the internal force responses of shear walls are considered. The higher modal contribution can not be neglected when computing the nonlinear earthquake responses of shear wall structures.

Abstract: This paper presents the results of a numerical investigation aimed at evaluation of damage accumulation in structures under different seismic sequences. For this purpose, a multi-story RC frame model representing the typical buildings was built and subjected to four sets of different repeating seismic sequences with different magnitude. The results indicate that the aftershock sequences will increase the damage accumulation in structures, and the damage index based on the Park and Ang model can qualitatively and quantitatively ascertain the damage state of the structure instead of the single index based on the lateral drift demands. Additionally, different sequences with the identical energy input will cause the same damage state in structures.

Abstract: Theoretical study on earthquake damage under seismic load about of concreate structure，in order to better study the damage evolution mechanism of reinforced concrete frame structure in earthquake. The two-parameter seismic damage factor model,which is based on deformation and dissipation,was improved using the theoretical analysis method in this study .Using the three-level earthquake-resistant design damaging index based on the importance of structure as the collapse criteria for evaluation. Using the nonlinear dynamic finite element method and do a collapse numerical simulation analysis of a three layers concrete frame. Calculate the dynamic response and damaging factor of each time step, and study the damage evolution.The results show that the improved damage index calculating model can calculate both on the maximum damage index and structure damage index quantificationally and continuously and describe the process of collapse damage of the integral structure.