Papers by Keyword: Damage Evaluation

Abstract: This study introduces a practical method for evaluating structural damage based on a large-scale simulation targeting expansive areas, like whole cities. In such a seismic simulation that deals with numerous building structures, it is desirable to estimate the damage based on a stochastic evaluation considering the uncertainty of structural properties. This is because an accurate modeling of numerous building structures, according to each designed value, would require a great deal of time. However, a damage evaluation considering the model uncertainty generally involves numerous calculations and is inadequate for such a large-scale simulation. Therefore, we propose a method using the point estimate technique which can estimate the probability of damage under model uncertainty from a small number of calculations. The applicability and usefulness of the proposed method is evaluated by comparing it to the method based on a Monte Carlo simulation.

Abstract: In this paper, time-series pattern recognition is applied for a damage evaluation sequence represented by a frequency response change due to a damage coefficient occurrence. The objective of this paper is parameters tuning of pattern recognition system which discovers dependencies between data entries in time-series. The influence of input parameters over the ability of the immune algorithm to identify similarity of historical sequences describing frequency response change of an object (antibodies) as a result of a damage coefficient occurrence to a sequence describing frequency response with a noise due to external disturbances (pathogen) is researched. The investigated parameters are: affinity threshold At, suppression threshold St, number of mutated genes Nm, number of iterations Ino and number of clones K. Antibodies (sequences) belonging to a given neighborhood represent a given type of damage. Antibodies from the neighborhood undergo clonal selection and affinity maturation process to achieve better affinity to the pathogen. With the best matched antibody the type of damage in the problem of time-series pattern recognition is achieved.

Abstract: This paper makes analysis on accelerated speed overload and hydraulic pressure after earthquake, as well as the relationship between the ground motion peak acceleration and the dam body displacement, dam body damage volume ratio, and dam facing damage volume ratio. According to dam body partition, this paper takes the ratio of over stress accumulative duration and stress required capacity as parameters, and studies arch local earthquake damage evaluation of dam body partition. After analysis, it is found that after arch dam experiences different geological process, there are damages in both sides of dam abutment and upper part of dam body, overstressed area expands continuously and local damages take place.

Abstract: A one-third scale single unit of 3-storey tunnel form building with foundation beam was designed, constructed and tested under out-of-plane lateral cyclic loading. This building was designed according to BS8110 with no provision for seismic loading. Tunnel form building was initially tested at ±0.01% , ±0.1%, ±0.25%, ±0.5%, ±0.75%, ±1.00%, ±1.25% and ±1.5% drifts until the structure lost its lateral strength (strength degradation). Then, the specimen was repaired and retrofitted using steel plate and angle which was positioned at the wall-slab joints that had suffered severe damages. A similar drift of displacement before retrofitting was repeated for the specimen after being retrofitted. Visual observation of damages, hysteresis loops, stiffness, ductility and equivalent viscous damping (EVD) of the specimen were analyzed and compared before and after retrofitting. The proposed retrofitting technique has increased its lateral strength by 26%. Fewer cracks occurred after retrofitting the specimen compared to before retrofitting. It can be concluded that steel plate and angle can strengthen the wall-slab joint and this method can be used to retrofit the tunnel form building if it had been damaged caused by earthquake excitations.

Abstract: The present paper presents the results of a study on the assessment of the damages caused by the arson that in March 2013 severely damaged the building of the "Science Centre" museum located in the western part of the city of Naples. The case is contextualized in the broader thematic of the evaluation of damages caused by intentional events to real estate assets. The peculiarity of the case under analysis appears particularly interesting both for the extend of damages caused by the fire and the methodological approach to be adopted for the “quantum” determination. The model implemented is based on the cost approach criterion, considering the physical and technological depreciation in the “status quo ante” the event. In particular, we will test a “functional component” approach to determine the depreciation function for each component due to the specificity of the scientific building under analysis. The results of the study confirmed that the proposed approach appears to be adequate to estimate the damage to the real estate assets, managing to capture the different components that contribute to determining the market value of the property at hand.

Abstract: Based on 6 testing beams in site cast, the mechanical behaviors of RC beams after reinforcement are analyzed. Concrete-replacing and grouting were used to reinforce the damaged component. When the reinforcement materials reached sufficient strength and maturity, beams were subjected to experiments of bending bearing capacity. Cracking load and ultimate bearing capacity were analyzed relatively, drawing some conclusions which could use as the reference of reinforcing concrete structure after damage.

Abstract: It is possible for hydraulic engineering located in high intensity earthquake area under the action of extreme disaster induced by earthquake and secondary slide surge. Several impact action models of slide surge were introduced and the damage evolution of concrete gravity dam subjected to combined action of different sequences of earthquake and secondary slide surge were studied based on nonlinear numerical analysis. The effects of different time sequences of combined earthquake and slide surge were compared and the safety performance analysis was performed. The results show that the combined form has great effects on the damage evolution law of concrete gravity dam.

Abstract: A double-walled liquid mercury target vessel, which consists of outer and inner walls, is being globally developed for MW-class spallation neutron sources. When proton beams bombard a mercury target, pressure waves are generated due to the rapid thermal heat deposition. These pressure waves trigger impulsive vibrations in the mercury vessel, and cause cavitation damage to the inner wall of the vessel. In this study, the dependency of the vibration behavior of the mercury vessel on the damage is systematically investigated through numerical simulations and experiments, for inner wall damage characterized by hole diameters of 1, 5, 10, 20, and 40 mm. A method referred to as wavelet differential analysis is developed, and a parameter referred to as average intensity is derived for a quantitative damage evaluation. Both the numerical simulation and experimental results show that the average intensity is damage-sensitive and depends on the damage feature size. The critical damage hole diameter is estimated to be 10 mm during damage evaluation.

Abstract: Orientation changes during fatigue crack initiation in ferrite and ferritepearlite steel were evaluated by electron backscatter diffraction (EBSD). Ferrite steel with different grain sizes and ferritepearlite steel with different carbon contents were prepared. EBSD measurements and fatigue tests were alternately performed using a small specimen. The tests on both ferrite and ferritepearlite steel suggest that the initial cracks were observed in the ferrite matrix. Thus, crystal rotation induced by fatigue in ferrite matrix is quantitatively evaluated by two misorientation parameters: grain reference orientation deviation, which is the misorientation between measuring points and the average orientation in each grain, and crystal misorientation at the same point before and after fatigue testing.

Abstract: By using the simple stiffness matrix formula of reinforced concrete (RC) cross-section under bending and compression, some RC cross-sections under bending and compression were traced through full path. Based on the numerical analysis, the damage of each point was calculated in a cross section, and the damage distribution of one member under the ultimate load was analyzed. This was agreement with experimental phenomena. In cross-section level, cross-section whole damage index was given and researched; and it could well explain cross-section mechanical behaviors.