Sharif Digital Repository

Cracks are the earliest signs of damage in structures which are needed to get detected through structural inspection before causing failure. Regular inspection and post-disaster inspection of structures are usually conducted manually by engineers. These kinds of visual inspections could be expensive, subjective, not reliable, and most importantly inefficient. Computer vision developments help automate this process by analyzing digital images captured from the surface of structures. Despite the fact that masonry structures have more complex surfaces than other kinds of structures, limited studies have focused on presenting machine-vision-based techniques for crack detection in those... 

Civil engineering structures and infrastructures including buildings and bridges are exposed to various externally applied loadings such as traffic, wind and earthquake during their operational lifetime. In this regards, structural static/dynamic displacement monitoring and their charactristics by mounted transducers is the mostly utilized and popular strategy. This may provide quantitative information for both structural safety evaluation and maintenance purposes. Such practice, however, is highly expensive to be operateddue to wiring, power signal transmission issues, limitations of sensor configuration to capture the entire structural response, and so forth. In addition, this may affect... 

Under conventional seismic design strategies, civil engineering structures are designed to undergo inelastic deformation to dissipate earthquake energy, leading to residual displacements and nonlinear deformations in the structure. As a result, there is an essential need for structural health monitoring methods to detect and process these nonlinear behaviors. In this dissertation, a model-free Hysteresis Loop Analysis (HLA) method is developed to identify damage and monitor the structure's performance online, under the earthquake excitations in both severe linear and nonlinear scenarios. The structural models used to validate this method includes three types of one-story, five-story, and... 

Damage and collapse of structural systems due to externally applied loadings, are inevitable, which cause financial and human losses. Therefore, the application of structural health monitoring (SHM) strategies has attracted a lot of attention in order to estimate structural damages, optimal maintenance and preventing structural collapse. Hence, in recent decades, the development of research activities in the field of structural health monitoring and its application in civil engineering, has led to the invention of various techniques and methods in assessing the safety of structures. These methods not only should be accurate enough for confidently identifying diverse severity of damages, but... 

In general, modeling errors cause incompatibility between experimental results and the numerical finite element model. To address this issue, the finite element model is being updated to identify the actual dynamic properties of the structure, to evaluate and estimate possible defects of structure, and finally to adapt the behavior of the numerical model and the real structure. As an optimization problem, unknown parameters of the identification model and parameters with uncertainty are being modified. Definition of an appropriate objective function, specifying up-to-date parameters and determining an efficient optimization method are the three main steps of a model-updating problem. On the... 

Due to inevitable uncertain sources in modeling, operational and environmental conditions, finite element model and structure’s response to a same load pattern differs drastically. To reduce this difference and make the model’s response close to the real structure, finite element model updating procedure is essential. Updated model can be used for structural assessment, damage identification, remaining service life estimation, and structural control. Model updating methods are categorized into two groups in term of information domain used for model updating; time-domain methods and frequency-domain approaches. Time-domain methods have a preference because of the main drawbacks of frequency...