In recent years, large-span metal roof is often exposed by wind. By analyzing and summarizing the reasons, this paper proposes an intelligent strengthening system for metal roof panel system. The structural health monitoring and distributed optical fiber sensing technology are organically applied to the metal roof reinforcement system. Based on the intelligent material reinforced fiber composite sensing material, which has both stress and sensor, and based on the distributed strain calculation, the high tensile capacity of the reinforced fiber composite sensor material is used to realize that the metal roof panel will not be lifted in the extreme wind days, At least achieve the effect of being lifted and not being blown away. This intelligent reinforcement system of metal roof based on optical fiber sensing technology is applied to the actual project of Xuzhou East Railway Station, hoping to provide reference for similar projects in the future.
In order to avoid the safety problems of the public building structure in the dense passenger flow environment, the structural health monitoring system is combined with the Building Information Modeling (BIM) method. This paper proposed a dynamic building information management system based on Structural Health Monitoring (SHM) information to ensure the security of its passenger flow information for a crowded exhibition hall. The continuous development of BIM (building information modeling) technology has greatly promoted the development of the construction industry. We can achieve real-time updating and visualization of sensor monitoring data and effectively manage different types of monitoring information as well as improve the controllability and safety of building structure monitoring by introducing BIM technology into structural health monitoring. A static building information model (BIM) was established to generate dynamic passenger flow information through video data learning, and provide a basis for structural health monitoring system for structural safety analysis and emergency response functions under dense passenger flow conditions. A dynamic building information management system suitable for structural health monitoring was built to display the dynamic network of traffic capacity in real time, so that the building information model is dynamic and predictable. The establishment for the combination mechanism of BIM and SHM system improved the data information circulation of BIM system. It could carry out dynamic health monitoring management and early warning control of building structures, realize information sharing in the process of health monitoring, and effectively improve the safety and operational efficiency of public building structures.
In the process of bridge health monitoring, in order to study the relationship between strain and temperature at the important position of the structure, based on the field monitoring data of the Changqing Yellow River Bridge in Jinan, this paper analyzes it. According to the time series of temperature and strain data collected in the field stable operation stage, the basic characteristics of temperature and strain data are obtained through characteristic analysis. The wavelet analysis method is used to decompose the temperature and strain data in four layers to get different level of detail signals, including the strain caused by high-frequency random load such as vehicle load and noise, the strain caused by dead load and material creep, and the strain caused by daily temperature change. The relationship between temperature and strain is obtained by comparing the signal layer related to daily temperature change with the time series of temperature change. The results show that: 1. Temperature has a great influence on the strain of the structure, and temperature and strain show a positive correlation. 2. In different positions of the structure, the longitudinal distribution of temperature is more uniform. 3. All kinds of strain signals are obtained by wavelet decomposition. In a word, the data analysis method and research results used in this paper provide an important reference for bridge health monitoring in practical engineering.
Structural temperature has been widely recognized as one of the most negative environmental effect on bridge. In this study, the temperature distribution of a large rigid-continuous concrete box girder bridge is investigated combining the numerical simulation and the field measurements. A temperature sensor system has be installed on the bridge for field monitoring the structural temperature. For simulation study, the fine tow-dimensional finite element (FE) model of box girder section is first constructed. Then, the time-dependent thermal boundary conditions are determined to extensively take account of environmental factors resulting of thermal effects on bridge. At last, transient heat transfer analysis is implemented on FE model and corresponding time-dependent temperature distribution is obtained. The analytical results are compared with the measurements for validation of the thermal analysis method. The results have very good agreements with the measurements, and the temperature variations exactly explicate the changes of environmental conditions such as solar radiation and ambient temperature of daily. The temperature simulation provides a foundation for the structural analysis of temperature induced effects.
The field measurements of structures are very important to the structural finite element (FE) model updating because the
errors and uncertainties of a FE model are corrected directly through closing the discrepancies between the analytical
responses from FE model and the measurements from field testing of a structure. Usually, the accurate and reliable field
measurements are very limited. Therefore, it is very important to make full use of the limited and valuable field
measurements in structural model updating to achieve a best result with the lowest cost. In this paper, structural FE
model updating is investigated in the point of view of solving a mathematical problem, and different amount and
category of structural dynamic responses and static responses are considered as constraints to explore their effects on the
updated results of different degree and types of structural damages. The numerical studies are carried out on a space
truss. Accounting for the numerical results, some inherent phenomena and connections taking account of the updating
parameters, output responses and the updated results are revealed and discussed. Some useful and practicable
suggestions about using the field measurements for FE model updating are provided to achieve efficient and reliable
Statistical analysis of vehicle loads on expressway in Dongying City in China was made to investigate vehicle loads on expressway in recent years. Results show that all the vehicle loads follow multimodal distribution, and cannot be described by a typical probability model. In this paper, the probability density function is simulated by a weighted sum of three lognormal distributions. The three peaks represent light, normal and heavy vehicles respectively. The multivariate extreme value distribution for heavy vehicles is simulated by the Extreme Value I Distribution. Finally the 0.95-fractals of maximum distribution of the three peaks are calculated for different time periods.
With the development of the application of visual tracking technology, the performance of visual tracking algorithm is important. Due
to many kinds of voice, robust of tracking algorithm is bad. To improve identification rate and track rate for quickly moving target,
expand tracking scope and lower sensitivity to illumination varying, an active visual tracking system based on illumination invariants
is proposed. Camera motion pre-control method based on particle filter pre-location is used to improve activity and accuracy of track
for quickly moving target by forecasting target position and control camera joints of Tilt, Pan and zoom. Pre-location method using
particle sample filter according to illumination invariants of target is used to reduce the affect of varying illumination during tracking
moving target and to improve algorithm robust. Experiments in intelligent space show that the robust to illumination vary is improved
and the accuracy is improved by actively adjust PTZ parameters.
Environment conditions such as temperature, humidity, traffic loadings and wind loadings cause changes in the
identified dynamic properties of bridges, which will affect health diagnosis based on the mode frequencies in bridge
structural health monitoring. This paper analyzed temperature effects on a rigid continuous bridge based on monitoring
data from Aug. 2006 to Dec. 2006. First, temperature data calculating process from measured data is given and
frequency time histories are graphed. Temperature effects on the bridge dynamic properties are divided into yearly
temperature change and sunlight radiation. Then, theoretical eigenfrequency functions of a simply-supported uniform
beam with and without axial force are provided to explain and distinguish temperature effects and constraints on
characteristic frequencies. Relationship of measured temperature and frequencies data are drafted and linear correlations
are found on the 1st and 3rd vertical frequencies. 2nd vertical frequency fluctuated cyclically in one day, caused by
sunlight radiation and restrains.
Modal analysis is an important tool for structural health monitoring based on measured acceleration data, which affects
the result of damage identification, safety evaluation and prediction. This paper starts with a brief review of modal
identification methods, and then introduces a rigid continuous bridge-Dongying Yellow River Bridge (DYRB) and its
structure health monitoring system. Amounts of acceleration data was collected from August to December 2006. The
peak picking method is adopted and enhanced with selected accelerometers using average and fitting methods. As a
result, the 1st transverse and first 3 vertical frequencies were identified accurately and efficiently. More researches are
needed to analyze the different appearance of different mode frequencies and to verify the influence of temperature,
moisture, wind, traffic load, etc.