Based on present research, there is a big difference between the estimation of the first frequency of Girder Bridge obtained by the design code of bridges, issued by department of transportation of China in 2004, and the theoretical value in some cases. To overcome above issue, theoretical analysis combined with numerical simulation was applied to estimate the fundamental frequency of Girder Bridge with uniform cross-section. The effect of the ratio between side span and central span on the estimating fundamental frequency was discussed in detail. Finally, an improved method was proposed to estimate the first frequency of Girder Bridge, and the effectiveness of the proposed method was verified.

Structural Health Monitoring is becoming an increasingly common tool to obtain the long-term performance of infrastructures and buildings. Many structural health monitoring systems were developed and applied to different bridges in the world. However, very little is known on the applications in extreme cold environment. Fu Sui Bridge, a 1070 m variable cross-section continuous box-girder bridge, is located in the coldest province -- Heilongjiang province, China. In order to monitor the static and dynamic responses of the bridge under the traffic and environmental variation, a long-term continuous monitoring system was designed and installed on Fu Sui Bridge in April 2012. A hydrostatic leveling system was used to measure the displacement and fiber Bragg grating sensors were used to measure strain, acceleration and temperature. Moreover, other necessary components including data acquisition and transmission, data calculation and analysis software are also described. Summer and winter monitoring data are also presented. This paper focuses on: (1) the design and installation of the long-term continuous monitoring system hardware and (2) the operating pattern and function of the automatic monitoring system. After more than one year successful conducting, the system has provided a large amount of data records for daily management and research of the bridge. This system can be applied to extremely cold region.

The reason situ stress is very complicated, and it is still not very clear question. In this paper, the construction process through practical engineering analysis on a variety of construction methods and steps arch tunnel to study the effects of different excavation methods and deep anchor support large section tunnel under guard by theoretical analysis of surrounding rock stress field, strain field and variation of the displacement field, analysis of different rock excavation methods, supporting stress state characteristics, in order to optimize the choice of tunneling method provides a theoretical basis. Under the conditions all kinds of rock reasonable steps to secure construction methods put forward and lay the foundation for long-term safety arch tunnel.

Ha Shuang Bridge is located in Harbin city within Heilongjiang province in the east north of China. The purposes of this study are to monitor the damage in structural members of Ha Shuang prestressed concrete box girder oblique bridge before strengthening and to evaluate the dynamic performance of the bridge structure by adopting dynamic load test. Monitoring process of damage of the bridge structure shows that the web of box girder in the quarter of the second span (about 10.5m from the pier) suffers from serious shear cracks. These cracks extend from the top to lower flange of box girder. The width of cracks rang from 0.5mm to 2mm and the angle is 45 degree. There are 6 bending cracks. The spacing between these cracks rang from 20cm to 30cm and the width is 035mm. In the span No. 3 near the pier, the web of box girder appears 12 diagonal cracks have width rang from 0.1mm to 0.12 mm. The results of dynamic load test analysis show that the values of measured vertical natural frequency is w1 = 3.616Hz and horizontal natural frequency w2 = 4.492Hz less than the values of theoretical natural frequency which is 3.863Hz and 4.848Hz, indicating that the actual stiffness of the bridge structure is less than the theoretical stiffness. Therefore the dynamic working state of bridge structure is not good. Therefore the working state of bridge is not good and it need to repair and strengthening.

To address the drawback of comfort evaluation on Highway Bridges due to moving vehicular loads, a large-span continuous girder bridge, namely Yilan Songhua River Highway Bridge, is studied in detail. The pedestrians comfort and riding comfort of the selected bridge under both single-vehicle and multi-vehicle are analyzed by our computer programs VBCVA (vehicle-bridge coupled vibration analysis) which is based on modal synthesis method and VCE (vibration comfort evaluation) which is based on existing common evaluation criteria. The peak accelerations of vehicles and the bridge are significantly influenced by the increase in bridge surface roughness as speed increases. Pedestrians acceleration induced by truck is larger than that induced by car. Except at the abutment span where the resonance speed is lower than other spans, the comfort of pedestrians at different locations of the mid-span are practically the same for various speeds. The riding comfort influenced by the truck on adjacent lane is dependent on the relative value between the dynamic response of the bridge and its roughness. For continuous girder bridges, because of the smaller dynamic response induced by the truck on adjacent lane compared to that induced by the roughness of the lane itself, the influence between adjacent lanes can be ignored. Finally, it is shown that the pedestrian comfort and riding comfort of the newly built Yilan Songhua River Bridge could meet the existing requirements in normal operation.