Advanced Materials Research Vols. 639-640

Abstract: Orthotropic plate participates in bridge structure as a part of steel box girder, while in Balinghe Bridge it is used as bridge deck directly to endure the wheel load [1]. In this paper it’s studied systematically the mechanical behavior of orthotropic steel bridge deck in combination with the deck model of Balinghe Bridge, and shows the positions emerging fatigue cracks to provide the basis for future health monitoring and put forward some suggestions.

Abstract: In order to ensure the safety of the bridge, Control surveying and monitoring was applied in many ways. This paper introduces the surveying and monitoring methods, analyzes the surveying accuracy, discuses the effective measures. In case study, Trimble 5700 GPS, TPS，Levels were used to perform the control surveying, and video camera, camera, georobot, three-dimensional laser scanner and other graph or image sensors were used to monitor bridge deformation. The research shows that the relative error of the control network baseline is smaller than 10-6 and the elevation accuracy is satisfied with the standard. The control survey enabled all surveying, mapping and monitoring activities to share a common geodetic reference system，provided a reliable support for the monitoring of the piers，box girders，coastal topographic details as well as hydrographic activities. And the application of modern sensors and the data acquisition technology reflected the real-time deformation conditions of bridge and provided forecasting and alarming information at any time by ways of number, curves, graph and image with high efficiency.

Abstract: The paper discusses guide survey system in long distance curved pipe jacking, presents a three-dimensional datum transformation model to determine the orientation of jacking pipe，The unitary principle and the new navigating method are introduced and the methods accuracy and variance are analyzed. The intelligence guide system is carried through easily associate with total station. The mathematical model, the operation principle, the hardware realization of extra long pipe jacking automatic guidance are introduced. Practice shows that all the reference points are used more efficiently in the new model than in the general model, and the surveying and navigating system gets enormous time-saving against conventional methods

Abstract: Detailed geological profile and complementary prospecting histogram revealed a series of hard rocks in the Line 9 tunnel of the Guangzhou metro, greatly increasing the difficulty of shield construction. The geological and hydrological condition of the project was very complex and vertical shafts were used to remove the rocks in order to reduce the cost of the project. Reverse construction technology was applied to the construction of vertical shafts. The calculation of internal forces and relevant design of the vertical shaft wall are introduced herein. The vertical shafts and surrounding buildings were monitored and the monitored contents are also described in detail. At the same time, some emergency measures were applied to ensure the safety of the project. The rocks removal technologies before shield-driving in the line 9 of the Guangzhou metro are introduced herein and the results can be referenced to other similar projects.

Abstract: The main structure of a performing arts center is in a bowl shape, formed by cantilever frames. When constructing, a temporary steel support system is designed to withstand the construction loads. The structural support system which is 30 meters high, is divided into five layers. In order to ensure the overall stability of the steel frame, scissors are set every three cross along the ring to the medial and lateral column. Since the loads are very big, bearing capacity and stability analysis of the support system are carried out. According to the site construction schedule, the loading processing is divided into 4 working conditions. Under each load condition, static and linear buckling analysis is conducted. For economic consideration, member sizes are optimized by pursuing the similar stress ratio based on the results of static and linear buckling. Structural software SAP2000 is employed as the analysis software. The results showed that: the working conditions 4 is the most dangerous working condition. The main stresses of beams and columns on the axis position are larger than other positions. The bucking analysis indicates that working conditions 1 to 4 the buckling factors of first-order buckling modes are greater than 1.0 under working conditions 1 to 4, which explaining that under the current loads, the steel support system is reached the required overall stability.

Abstract: In a performing art center project, the roof system uses steel trusses with large-span, which challenges the installation of trusses in construction. Two SCC400 hydraulic crawler cranes are arranged to lift roof trusses. Since it is impossible to sustain the huge cranes for structural slabs, an independent steel trestle will be constructed along the moving path of cranes. The steel trestle is a special frame system with three kinds of levels. Constrained by constructed basement structures, steel trestle has a complex shape and some long span members. It requires some members high capacity and stability. To investigate its mechanics properties, especially the whole stability, a set of analysis, including static and elastic buckling analysis, are carried out on this steel trestle by use of ANSYS software. According to the working conditions of crawler cranes, the loads caused by walking of cranes and hoisting trusses are considered. On the basis of the static analysis, the dangerous loading areas are determined to conduct eigenvalue buckling analysis. The results show that the loads in different positions have less impact on the force and deformation of the entire structure. The buckling characteristic value of the first four modes in both load conditions is larger than 1, which indicates that the system has enough stability.

Abstract: Pre-stressed concrete continuous rigid frame bridges have been widely used for modern long-span bridges due to its advantages, such as comfortable for travelling, easy to be constructed and maintained etc. However, cracks and excessive mid-span sag of box girders generally exist in many built bridges of this kind during service, and because of its large size and the complex natural environment, it is particularly important to study the long-term performance based on the long-term field measurements. In this paper, a high-pier & long-span pre-stressed concrete continuous rigid-frame bridges, with five-spans (106m+3×200m+106m), was taken as the research object, by pre-embedding strain sensors in mid-span sections and root sections on box girders, field-tests for stress variation were conducted in extreme weather conditions (ie, the hottest and coldest in one year) after its completion in two years, providing tested data for studying long-term performance of bridges similar to the same kind.

Abstract: It is necessary to simulate construction and operation and analyze monitoring data in time for dynamic construction and reinforcement design of high-fill slope. As a typical example, some high-fill slope is calculated with limit equilibrium method for evaluation of the slope stability. The slope is also calculated with finite element method (FEM) and monitored during construction and operation. FEM stress and displacement results are in good agreement with in-situ monitoring data. Combining FEM computation with monitoring analysis is the main process of dynamic design which guides construction and reinforcement and assures safety.

Abstract: The tunnel involved in this study is a double-track tunnel with a 4113m length and 390m maximum depth which is currently under construction. By analyzing the specific engineering geological and hydro geological conditions and summarizing the past geological prediction techniques, the comprehensive geological prediction methods are adopted in the project, and the accuracy and feasibility of the theory and techniques are verified in the practical construction process. It is concluded that the comprehensive geological prediction methods are conducive to reduce the risks, accelerate the schedule and guarantee the quality of the construction, and provided a good guidance and reference for the tunnel constructions of this kind

Abstract: In order to realize the monitoring for the large-scale structures and find the change of its condition, a new damage feature factor is put forward. The damage feature factor is based on the PCA (principle component analysis) theory, analyzing the object of AR (Auto-regressive) model coefficient by the constant load, utilizing the theory of ellipse control figure. Then a program is designed combining the damage identification method with LabVIEW. Finally, an experiment is conducted on a steel frame model under different conditions. The results show that the first two principle components contain the main information of the structure condition, and the method can identify the changes of the structure condition correctly. Besides, the program works well and gives sound and light alarm under the damage condition.