Applied Mechanics and Materials Vols. 361-363

Abstract: Closure sequences of rigid frame-continuous girder bridge are analyzed by calculation to compare girder deflection change, pier horizontal displacement maximum, girder and pier stress value. The results show that the first side span-second side span-mid span closure sequence causes the largest girder vertical displacement and others cause almost the same vertical displacement; side piers pier top horizontal displacement is larger than middle piers whatever the closure sequence is, closure sequences could not change the stress of the girder and pier. The first side span-mid span-second side span closure sequence should be preferred.

Abstract: The main bridge of Zhengzhou Yellow River 2nd bridge is a concrete filled steel tubulur (CFST) arch bridge. Choosing the main bridge as the research object, the finite element procedure ANSYS was used to establish the 3D finite element dynamic model. In order to analyze the influence of structural Parameters variation on dynamic characteristic,17 different conditions were considered in the calculation and analysis process. The results show that the CFST arch bridge is a flexible structure. The vertical rigidity of the bridge is stronger than the lateral rigidity CFST arch rib. The changes of the transverse brace style have little effect on the vertical rigidity, but have great impacts on the lateral rigidity of the CFST arch rib. It is sensitive on the first step vibration if the bracing tube damage. But the bracing tube damage has little effect on the vertical rigidity. The damages of suspenders and bridge deck slabs influence weakly on the vibration modes.

Abstract: On the basis of experimental studies on the bending resistance of FRP reinforce bridges under the effect of limited overload with high preloading amplitude values, the relationship between FRP amounts and ultimate loads is analyzed and influences of limited overload on flexural strength, deflection, crack width and height of bridges are fatherly studied. Thus damage effect rules of FRP reinforce bridges are concluded which provide scientific technology supports for the application of fiber reinforce plastic on bridge reinforcement.

Abstract: Xiangjiang Bridge is a newly built bridge. In order to understand the actual working condition and the bearing capacity of the bridge, the static and dynamic tests are carried out. This paper describes the principles and methods of the load test and the measurement of the stiffness and dynamic characteristics of the bridge structure. Through analyzing the test, the data and information of bridge can be accumulated and the mechanical characteristic of this kind of bridge is discussed.

Abstract: To reduce traffic disruption due to a live-cycle and seismic damage it is necessary to study the causes in infrastructures and bridges. When we talk about steel structures and in particular steel bridges, we know that they are very flexible and consequently easy to identify by ambient vibration methods. In a collaborative project between the University of Padua and the Italian Railway Authority, two old reticular steel bridges (1920) were subject to in-situ structural identification, demolition and consequent laboratory fatigue tests. On account to their similarity it was possible to acquire dynamic data for several days by using the same acquisition logger and 12 acceleration sensors After the data of the two analyzed reticular bridges have been filtered, accurate vibrating modes were identified by using both time and frequency domain techniques and the results were outstanding. In order to use best-fitted material characteristics in the elements of the structures, destructive and non-destructive tests were executed. The results permitted to realize very accurate finite element models and calibrate them for successive fatigue scenarios by comparing laboratory and numeric tests.

Abstract: In the design of long-span bridge , it is necessary to lay the expansion regulator in order to reduce the beam-track interaction. Take the Zhengzhou-Xi’an high-speed railway as an example, the paper created a CWR mechanical model on the bridge using the finite element software ANSYS, proposed the deformation law of the structure and its stress characteristics. Based on the fiber grating testing technology, many monitoring points were laid on the Weihe bridge, to make a long-term monitoring. Processed the monitoring data about rail temperature and temperature force of the regulator, the CWR service conditions were assessed. The study shows that the scheme laying a set of regulator on the longest span Weihe bridge has greatly decreased the beam-rail interaction. All of its design parameters are reasonable. The operation safety indexes can completely meet the need of limits.

Abstract: To solve the abnormal rail corrugation problem of Beijing Metro Line 4, the track structural parameters comparative tests were carry out in the Metro Line 1,2 and 4. Metro Lines 1 and 2 were chosen based of the Beijing Subway Survey and previous successful experiments. The comparative analysis was based off of rail static geometry, dynamic displacement and the lateral acceleration. The test results proved the stiffness of line4 is weaker than line1,2 and suggestions on steps to prevent and correct the metro rails abnormal corrugation will be formulated.

Abstract: Subgrade resilient modulus of 3 typical soils, namely sand, silt and clay, have been measured under different conditions of 2 target dry density and 3 target water content by triaxial repeated-loading test. Analysis has been focused on the effect law of subgrade moisture and compaction for resilient modulus based on test results. Subgrade moisture has some impact on resilient modulus of test soils, especially on that of fine-grained soils. The influence degree of subgrde compaction depends on soil group. Coefficient of moisture modification has been introduced to characterize relationship between subgrade moisture and resilient modulus. Two-parameter Logistic model with inflexion control has been proposed according to the following basic rule. Coefficient of moisture modification usually increases or decreases along with the decrement or increment of subgrade moisture. And then variety rate of coefficient becomes small in state of high or low water content.

Abstract: There is a huge impact of railway projects on the regional environment. A life cycle assessment (LCA) framework using quantitative methodwas developed to evaluate the environment impact of railway projects quantitatively. The railway life cycle was divided into 5 phases: survey and design, raw materials processing, construction, operation, and demolition. The life cycle environmental impact for railway project was categorized into 5 grades: great negative influence, little negative influence, no influence, little positive influence, and great positive influence. Based on the improved AHP method, a quantitative method was introduced to evaluate comprehensive environmental impact of railway projects. A railway project was analyzed as a case study. The results show that the major environment impact is occurred during the phases of operation and demolition. It is demonstrated that the method is applicable to assess the life-cycle environmental impact of railway projects.

Abstract: Taking the slope of K178+500-K178+550 of Beian-Heihe expressway as example, based on the steady saturated-unsaturated seepage theory and simplified the seepage force of groundwater into equivalent nodal load, then using the strength reduction finite element method to analysis the stability and potential slide area of roadbed slope which has no engineering measures; the interaction between slide-resistant pile and weathered rock can be reasonably considered by using the contact surface element, the result shows that, the safety factor of roadbed slope can be improved and the shearing strength of roadbed slope can be evenly dispersed by the reinforcement measure. The result can be used for the stability evaluation and reinforcement of subgrade slope of weathered rock area.