Temperature Effect On The Dynamic Characteristics Of An RC Slab

With the development of civil engineering technology, damage identification and structural health monitoring has been more and more widely used in engineering. At the some time, vibration-based detection technology also has been significant development. That is, by measuring the vibration characteristics of the structure (natural frequency, damping, etc.), to test the strength or judge the defects. Changes in environmental conditions such as temperature and humidity affect structural vibration properties, modal frequencies varied significantly in a single day due to temperature change. Therefore, it is necessary to discriminate the variation of modal properties due to environmental change from those caused by structural damage, and quantify the environmental effect in vibration-based structural health monitoring and damage identification.In addition, environmental conditions affect structural vibration properties in a complicated manner. The environment factors, such as temperature, humidity and other factors, change the temperature, humidity and damping in structure slowly. This is a gradual process, the performances of the structure change with the change in environment, there must be a certain relationship between them. However, in engineering practice, the changes in environmental factors can only be measured, the change of structure characteristics, such as temperature, humidity and other factors, can not be measured directly. Therefore, it is necessary to study the relationship between environmental factors and the characteristics of structures, so that the change of characteristics in structures can be obtained from the date of environment in practice.Based on the above analysis, this thesis focuses on the relationship between the internal temperature and natural frequencies of structures, and studies the effect of environmental temperature to the internal temperature and the impact of vibration frequencies of reinforced concrete slab. The main content includes: the data of the pilot collected, establish the function between internal temperature and vibration frequencies of a reinforced concrete slab; analysis of the ambient temperature of reinforced concrete and the internal temperature of the relationship between the derivation and the establishment of this model to describe the phenomenon of lagging; the establishment of one-dimensional model of heat conduction, derived the temperature of different place in the RC slab at different times and compared with the measured value.Finally, the test date analysis showed that the natural frequency of the structure decrease with the temperature increase.