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Paper Information

Journal:   MODARES CIVIL ENGINEERING JOURNAL   APRIL 2017 , Volume 17 , Number 1 ; Page(s) 203 To 215.
 
Paper: 

VIBRATION-BASED DAMAGE IDENTIFICATION OF MASONRY WALLS USING DISTINCT ELEMENT MODELING

 
 
Author(s):  MADAHI N., KHAJI N.*
 
* FACULTY OF CIVIL AND ENVIRONMENTAL ENGINEERING, TARBIAT MODARES UNIVERSITY
 
Abstract: 

Dry-joint construction method is among the oldest techniques adopted in most of the ancient and historical masonry buildings. Historical structures constructed using this method are highly vulnerable today. In addition, the strength of mortar is strongly affected–in most cases- by the passage of time and corrosion. Thus, the structure behavior would most likely be dependent on the dry-joint characteristics. Therefore, non-destructive dynamic-based methods are attractive tools to assess the existing damages of masonry walls, as they are capable of capturing the global structural behavior. In this paper, micro-modeling approach is adopted for the evaluation of masonry walls. The approach is based on the application of Distinct Element Method (DEM) as assemblies of units consist of block and mortar. Idealization of discontinuous nature governing the nonlinear mechanical behavior of the mentioned units is considered trough the modeling approach. Due to the heterogeneous and complex behavior of the interface between blocks and mortar, DEM seems to be the best-adapted approach for modeling this kind of structures, in particular for reproducing complex nonlinear post-elastic behavior. At the first step, micro-modeling strategy is used for masonry walls by DEM, and particularly post-elastic behavior is verified with valid experimental data. However, DEM does not directly obtain natural frequencies and mode shapes of the wall via a classic vibrational analysis. Therefore, the second objective of this study is to propose a technique to indirectly identify dynamic characteristics of masonry walls using DEM. The aim of this part is to check the capability of dynamic identification procedure, in the extraction of the dynamic characteristics of the masonry wall in the used DEM software. For this purpose, the dynamic behavior at low vibration levels of an existing masonry building subjected to forced hammer impact test, was investigated. By transforming the collected data of the dynamic response of wall from time domain to frequency domain -using Fast Fourier Transform (FFT) - natural frequencies can be found from Fourier amplitude spectrum. The proposed technique is then validated by comparison with the results of modal analysis which was carried out using Finite Element Method (FEM). The dynamic characteristics of walls (i.e., natural frequencies and mode shapes) may change when different levels of damage are induced to the wall. The proper knowledge of these variations is a key issue in order to study the seismic demand and seismic performance of structures. Aiming at finding adequate correspondence between dynamic behavior and internal crack growth, several numerical simulations are performed; progressive damage is induced in the wall; and sequential structural frequency identification analysis is then performed at each damage stage. In this paper, frequency and drift are selected as dynamic behavior and crack growth indices, respectively. Quantifying the relative frequency drop shows that although the shape does not vary significantly with increasing damage, there is a relation between frequency drop and damage variations -based on analyzed data. These properties are firstly modified in the elastic range, and then are developed in the inelastic range with increasing damages. It is also observed that while the failure mode of the wall is the diagonal cracking, the in-plane vibration mode shapes are much affected by the initiation of crack. On the other hand, modal properties of out-of-plane mode shapes are affected less by the diagonal crack.

 
Keyword(s): DAMAGE IDENTIFICATION, MASONRY WALLS, DISTINCT ELEMENT METHOD, FREQUENCY DROP
 
 
References: 
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Click to Cite.
APA: Copy

MADAHI, N., & KHAJI, N. (2017). VIBRATION-BASED DAMAGE IDENTIFICATION OF MASONRY WALLS USING DISTINCT ELEMENT MODELING. MODARES CIVIL ENGINEERING JOURNAL, 17(1 ), 203-215. https://www.sid.ir/en/journal/ViewPaper.aspx?id=570297



Vancouver: Copy

MADAHI N., KHAJI N.. VIBRATION-BASED DAMAGE IDENTIFICATION OF MASONRY WALLS USING DISTINCT ELEMENT MODELING. MODARES CIVIL ENGINEERING JOURNAL. 2017 [cited 2021May09];17(1 ):203-215. Available from: https://www.sid.ir/en/journal/ViewPaper.aspx?id=570297



IEEE: Copy

MADAHI, N., KHAJI, N., 2017. VIBRATION-BASED DAMAGE IDENTIFICATION OF MASONRY WALLS USING DISTINCT ELEMENT MODELING. MODARES CIVIL ENGINEERING JOURNAL, [online] 17(1 ), pp.203-215. Available: https://www.sid.ir/en/journal/ViewPaper.aspx?id=570297.



 
 
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