Changing environmental conditions, especially temperature, have been observed to be a complicated factor affecting vibration properties, such as frequencies, mode shapes, and damping, of civil structures. This paper reviews technical literature concerning variations in vibration properties of civil structures under changing temperature conditions. Most of these studies focus on variations in frequencies of bridge structures, with some studies on variations in mode shapes and damping and other types of structures. Statistical approaches to correlation between temperature and frequencies are also reviewed. A quantitative analysis shows that variations in material modulus under different temperatures are the major cause of the variations in vibration properties. A comparative study on different structures made of different materials is carried out in laboratory. Two real structures, the 1377 m main span Tsing Ma Suspension Bridge and the 610 m tall Guangzhou New Television Tower, are examined. Both laboratory experiments and field testing, regardless of different construction materials used and structural types, verify the quantitative analysis. Variations in frequencies of reinforced concrete (RC) structures are much more significant than those of steel structures.

Structural health monitoring (SHM) is a relatively new paradigm for civil infrastructure stakeholders including operators, consultants and contractors which has in the last two decades witnessed an acceleration of academic and applied research in related areas such as sensing technology, system identification, data mining and condition assessment.SHM has a wide range of applications including, but not limited to, diagnostic and prognostic capabilities.However when it comes to practical applications, stakeholders usually need answers to basic and pragmatic questions about in-service performance, maintenance and management of a structure which the technological advances are slow to address.

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The Tsing Ma Bridge in Hong Kong is a long suspension bridge. A wind and structural health monitoring system (WASHMS) has been installed in the bridge and operated by the Hong Kong Highways Department since 1997. The WASHMS is devised to carry out the monitoring of environmental status, traffic loads, bridge features and bridge responses. The environmental status includes temperature environment monitored by temperature sensors, whereas the bridge responses contain displacement responses recorded by displacement transducers, level sensing stations, and global positioning systems (GPS). Bridge displacement responses are, however, induced by a combination of four major types of loadings due to wind, temperature, highway, and railway. This investigation focuses on the temperature environment and the predominating temperature effect on the Tsing Ma Bridge. The main features and the pertinent monitoring system of the Tsing Ma Bridge are first introduced. The data collected from the four types of sensors are pre-processed. The statistics of ambient air temperature, effective temperature and displacement response of the bridge are then figured out based on the measurement data. The statistical relationship between the effective temperature and the displacement of the bridge is finally established. These results are useful for monitoring temperature effects on the Tsing Ma Bridge. Since the movements of the bridge are often accommodated by the bearings and expansion joints, large forces may develop in the bridge structure if any components of the movement are restrained. These forces sometimes may cause damage to the bridge.Churchward and Sokai [1] instrumented a section of post-stressed concrete bridge for recording of temperature profiles at different instants of time. It was found that the temperature profile could be reasonably predicted using two design variables, namely the maximum differential temperature and the effective temperature. Similar work was carried out by Au et al.[2] and Tong et al.[3] for both composite bridges and steel bridges in tropical region. Moorty and Roeder [4] attempted to relate the movements of a bridge to the temperature environment. Analytical methods were developed to obtain temperature distributions and the maximum bridge temperature ranges. Thermo-elastic analysis was conducted to obtain the temperatureinduced movements and the associated stresses in bridges. A field test was then conducted on the Sutton Creek Bridge in Montana, U.S.A. to verify the analytical models. A comprehensive research program on the Confederation Bridge in Eastern Canada has also been started in the spring of 1997 and will continue over many years to evaluate the effect of temperature on the short-term and long-term behavior of the bridge [5,6].The Tsing Ma Bridge in Hong Kong is a long suspension bridge carrying both highway and railway. A wind and structural health monitoring system (WASHMS) has been installed in the bridge and operated by the Hong Kong Highways Department since 1997 [7]. The WASHMS is de...

It is important to take into account the effect of temperature in assessing the structural condition of bridges. However, very few quantitative studies have examined the temperature behavior of large-scale bridges because of their large size and complicated configuration. This paper, for the first time, investigates the temperature distribution and associated responses of a long-span suspension bridge-the 2132-m-long Tsing Ma Bridgethrough a combination of numerical analysis and field monitoring. With appropriate assumptions, fine finite element models of a deck plate, section frame, and bridge tower are constructed to facilitate thermal analysis. With ambient temperature measurements and a solar radiation model, the time-dependent temperature distribution within each of these components is calculated through transient heat transfer analysis. The numerical results are verified by comparing them with field monitoring data on temperature distribution and variation at different times and in different seasons. The temperature data are then input into the structural model of the whole bridge to obtain the displacement and strain responses of various bridge components, with a good level of agreement being achieved between the bridge responses and the monitoring data. This exercise verifies both the accuracy of the analytical method employed and the effectiveness of the monitoring system installed on the bridge. The study shows that integrating numerical analysis with field monitoring data provides for a thorough understanding of the temperature behavior of long-span bridges.