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Yang Q.-W.,Shaoxing Institute of Arts and science | Zhou W.-D.,Huahui Engineering Design Group Co. | Liang C.-F.,Shaoxing Institute of Arts and science
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

The static response-based structural damage identification methods have received much attention in civil engineering field in recent years. A static rank analysis of a structure's system matrix method was presented here for structural damage identification using its static response data and the matrix rank analysis theory. Firstly, the rank varying of a structure's system matrix due to its damage was analyzed and then a limited rank solution formula of structural flexibility perturbation was developed. With the flexibility change determined, the elemental damage parameters were calculated by using the new flexibility perturbation method. According to the elemental damage parameters, the damage position and damage level were determined. Being different from the existing detection techniques, using the presented method could directly compute the damage parameters with the incompletely measured static data. The efficiency of the proposed method was demonstrated with a numerical example. The effect of measurement of noise on damage detection performance of the proposed method was also investigated. The results showed the good efficiency and stability of the proposed method for the identification of damage of a structure with more than one element. For the case with 3% and 10% noise, the prediction obtained was also reasonable. Source


Zhang X.,Hunan University | Gong G.,Hunan University | Zhou J.,Huahui Engineering Design Group Co.
Key Engineering Materials | Year: 2012

Compound condensing heat pump combines the advantages of heat pump technology and condensing heat recovery technology. It takes full account of the common infrastructure in the cooling and heat source system and greatly increases equipment utilization ratio. It also recycles condensing heat to produce sanitary hot water efficiently while ensuring cooling and heating of heat pump to achieve the same effect. The distinctive technical features of the compound condensation / evaporation of four functional heat pump ensure its efficient and reliable operation. This heat pump system runs in several models throughout the year, which include the refrigeration mode, refrigeration & domestic hot water mode, domestic hot water mode and heating mode. The performance in refrigeration mode and refrigeration & domestic hot water mode is studied by a designed experiment is done and the an explicit analysis is made. By comparing the results of simlation and experiment, an agreement can be shown clearly. Therefore, the final conclusion is drawn: the performance of compound condensation / evaporation of four functional heat pump is improved over the traditional heat pump. It is worthy to further promote for the sake of energy saving. © (2012) Trans Tech Publications. Source


Zhou W.-D.,Huahui Engineering Design Group Co. | Yang Q.-W.,Shaoxing College | Zhao W.,Jinan University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2013

A generalized flexibility perturbation approach for structural damage detection was presented here under ambient excitation. By appropriately converting the generalized flexibility perturbation equation, the mass normalization coefficients a structure's first several modal of shapes and the elemental damage parameters were calculated simultaneously using the least-square method. With the proposed approach, not only the damage level of the structure was recognized, but estimates of the mass normalization coefficients also were obtained. The effectiveness of the proposed method was illustrated using the simulated data and the measured noise for an example of a two-storey frame structure. The results showed that the proposed method can be used to identify structural damages accurately only using a structure's first several modal shapes; the predicted mass normalization coefficients of the measured modal shapes with the proposed method have a good accuracy; the proposed procedure is computationally attractive and simple to implement, it is useful for structural damage identification under ambient excitation. Source


Zhou W.,Huahui Engineering Design Group Co. | Yang Q.,Shaoxing University | Zhao W.,Jinan University
Jixie Qiangdu/Journal of Mechanical Strength | Year: 2014

A flexibility difference method based on the minimum-rank solution for locating damage in beam structures has been proposed in this paper. This method is based on the estimation of changes in the flexibility matrix by using the static response data and the minimum rank update theory. The main advantage of using the static data rather than dynamic data is that the static equilibrium equation is solely related to the structural stiffness, and accurate static response data can be obtained rapidly and cheaply. As distinct from the existing minimum-rank methods, the presented method can directly compute the flexibility perturbation using the incomplete measured static data. Moreover, the proposed theory provides an insight to the appropriate number of the applied static loads for structural damage detection. The efficiency of the proposed method is demonstrated by two numerical examples. The results show the good efficiency and stability of the proposed method on the localization of damage. It has been shown that the proposed procedure may be a promising method in structural damage localization. Source


Xiang Y.Q.,Zhejiang University | He X.Y.,Zhejiang University | Xing C.,Zhejiang University | Kordestani H.,Zhejiang University | Shao L.H.,Huahui Engineering Design Group Co.
Bridge Maintenance, Safety, Management and Life Extension - Proceedings of the 7th International Conference of Bridge Maintenance, Safety and Management, IABMAS 2014 | Year: 2014

In this paper the major types of piers, abutment and foundation in substructure of RC or PC bridges in China are summarized. The main types of defects occurring in substructure of concrete bridges including uneven settlement of foundation, lower carrying capacity, durability defects of reinforced concrete and cracking of concrete pier columns as well as abutments and cap beams have been pointed out. In addition to the concrete pier, abutment and foundation, the causes and mechanisms of these defects were analyzed from different points of view such as design, construction, maintenance and operation management. The relevant maintenance and strengthening methods were discussed and put forward, such as the foundation enlargement method, adding pile method and artificial foundation reinforcement method for concrete and RC pier or abutment foundation, the method of RC pier columns reinforced by RC hoop or FRP for piers, the reinforcement method of pasting steel strip or plate, the method reinforced by external prestressed tendons and additional support columns method for RC cap beams, the method of reducing load, the method of reducing fill height by adding numbers of approach spans, the support beam method and the method reinforced by auxiliary retaining wall for RC abutments. It is possible to recover the function of the RC or PC bridges and enhance their durability and load carrying capacity by employing corresponding maintenance and strengthening measures. At the same time, vehicle overload should be strictly limited according to the structural safety matters. © 2014 Taylor & Francis Group. Source

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