Applied Mechanics and Materials Vols. 578-579

Abstract: It’s very important to ensure the safety of buildings by using information technology in the dynamic monitoring of masonry. The digital camera in this research is non-measurement camera which has no box marks and orientation equipment, so it’s hard to get instant photography and external orientation elements. But we use methods to establish a reasonable mathematical model, this makes the monitoring possible.

Abstract: For there are many problems such as large amount interference factors, the amount of data collected is small, and so on occur in monitoring and forecasting, use the model that combine grey system and neural network to forecast. That is predicting with single model first, and then taking the prediction result of grey system as input sample value of BP neural network. Considering the measured values as objective sample value of network, neural network used to deformation forecast can be obtained through training. Prediction results show that this method can obtain a good forecasting result.

Abstract: By means of the wavelet analysis theory, the damage identification of plane frame was studied. Based on the finite element analysis of modal parameters, the method using the wavelet analysis of rotation mode was proposed for plane frames crack identification, and the mexh wavelet transform was applied to analyze the rotation mode of plane frame, so the location of crack of the plane frame can be identified by the maximum of wavelet coefficients. Taking one-story plane frame for example, the finite element model, each frame beam and column with a crack, was seperately set up, and the above-mentioned method was applied to identify the location of the crack, and the results validate this method. Finally, compared with the result of the wavelet transform to analysis vibration mode and rotation mode, it can be concluded that the method using the wavelet analysis of rotation mode is more convenient and more effective. This method may be useful in damage identification and diagnosis in structures.

Abstract: Damage of steel truss structure can be determined by the sudden change of correlation dimension which was obtained from the structural vibration response through fractal theory. The streel truss structure was as exampled to verify this method. The results show that: this method can determine the damage location of the structure whether single damage or multi damage and can preliminarily judge the damage degree.

Abstract: Due to inappropriate protective measures during construction, building structures in cold regions can easily suffer from frost heaving damage during the wintering period. Such damage is relatively invisible and can hardly be detected. According to the actual engineering conditions, this paper comprehensively analyzes the destructional form of each building element at low temperatures as well as discusses the methods to detect and evaluate damage of buildings at low temperatures. The author finds that: Under low-temperature environment, punching failure often occurs between the foundation slab and bearing platform and the anchor connection between the pile and bearing platform can easily become ineffective.

Abstract: As the complex structure, large size, hot climate, aggressive corrosive environment and high concrete strength grade for Super-large Section Precast Immersed Tube of Hong Kong-Zhuhai-Macao Bridge, crack control of concrete was difficult. On the basis of simulating analysis on thermal stress, temperature control design was carried out. Harmful crack could be effective controlled by series of treatment measures during construction period such as optimization of raw materials, preparation of low heat and shrinkage concrete, controlling concrete raw material temperature, mixing concrete with ice shavings and cooling water, setting up automatic maintenance system and automatic temperature monitoring system. From the monitoring results, the temperature monitoring results were consistent with the simulation data, and the maximum temperature and the temperature difference between concrete surface and internal concrete were met the requirement of temperature control standard. Moreover, the precast immersed tube didn’t appear harmful crack.

Abstract: Much concern has been paid on the human-induced vibration of high-speed railway station structures in recent years. But the vibration responses are influenced greatly by are two key factors, which are rational pedestrian load model and accurate structure calculation model. Field test, therefore, is the most directly and valuable method to obtain the vibration responses of large-span railway station structure. The vibration responses of the waiting floor of the Hangzhou East Railway Station, which is just completed, are measured and analyzed. The test results showed that the vibration of waiting room floor under pedestrian load cannot be neglected for vibration comfort evaluation.

Abstract: channel - masonry - concrete composite structures underpinning is a new type of underpinning technology, the two channel steel and the concrete of compression flange and the masonry between the channel combined into an overall flexural members, it can used in masonry structure underpinning the transformation of the wall, it has simple construction, safety and reliability, the combination of large carrying capacity and other characteristics. Through this combination of three members in bending tests, we can get, reinforced by setting off key, channel, masonry and concrete can form a combination of flexural members to work together, channels tensile stress, concrete bear stress, masonry between the channel improved stability of the web and shear capacity of the beam, we gives the flexural capacity calculation method of the composite structure through analysis.

Abstract: Through the investigation, detection, analysis and study of cracks in concrete beam and concrete floorslab of a residential project in Shandong Province, this paper aims to determine the cracks type and the causes, and assess the impact on the project. Then, the appropriate and corresponding schemes for handling concrete cracks will be developed and for similar projects, this paper proposes some reasonable suggestions as well.

Abstract: This paper made the same size of reinforced grouting material vertical bending cantilever beam and reinforced concrete ones, respectively for the same static and dynamic load test, the static load for drab one-time loading level, dynamic load as low reversed cyclic loading, observe their cracking and deformation condition, draw the response relationship between the load and displacement hysteresis curves, skeleton curves, Test and data results show that the stress and deformation of the reinforced grouting material member is close to or even better a reinforced concrete member, so it is reliable to replace concrete with grouting material.