The vibration method is used widely to estimate the cable force based on its relationship to frequency. The accuracy and the applicability of the vibration method can be improved through a more robust incorporation of the influential factors and a precise measurement of the frequency. An advanced vibration method was proposed in this paper to minimize the error of the cable force in long-term monitoring. The influential parameters on the accuracy of the vibration method including the flexural stiffness, sag-span ratio, inclination, and the boundary conditions of the cable were analyzed. Then the factors resulting in the error of the frequency data acquisition were presented. Based on the results, the conditions when those influential factors should be taken into account were determined, and the range of the error caused by the inaccuracies of the frequency measurement was given. A comprehensive optimized approach was finally established to determine the cable force based on the previous analysis. The accuracy and the feasibility of the proposed method were confirmed by a successful monitoring of a cable stayed bridge and a special shaped steel arch bridge.
In current accelerated bridge construction, grouted sleeve connections are widely used to connect bridge substructures, such as prefabricated piers and abutments. Grouting material age is the main factor affecting the mechanical properties of the sleeve connections, which in turn affects the efficiency of the accelerated bridge construction. On the basis of varyingly aged grout specimens, this article presented an experimental test regarding the influence of grout age on the mechanical properties of grouted sleeve connections. The specimens were loaded on the universal testing machine, and their interior failure mode was analyzed using industrial Computed Tomography (CT) detecting technology, which is a method of examing structures by scanning X rays. The results revealed that the bearing capacity of the 1-day-old grouted sleeve connection can reach the yield strength of the connection bar. After 14 days, the sleeve’s connection strength remained basically stabilized. Moreover, the failure of bonding interface between the bar and the grouting material mainly occurred in grouted sleeve connections. Based on the measured load–displacement data before the bar yield, model parameters related to grout age and the stress-slip model of the bonding interface between bar and the grouting material are presented, which can guide the mechanical analysis and the design of grouted sleeve connections.
Irregular-shaped footbridge scheme was determined due to urban landscape requirements, the subway constraints under the bridge and crossroad traffic condition. But the deformation and vibration of Irregularshaped structure will be complicated. To study the static behavior and vibration serviceability of Qingchun irregular-shaped footbridge in Hangzhou, the support reaction under the temperature influence and dynamic performance in pedestrian was calculated by using finite element method. The results of analysis show that the uneven deformation of irregular-shaped structure caused by temperature load will lead to support separation, and this issue can be solved by adding additional weight near the top of the pier; First-order vertical frequency needs to be increased by adjusting the beam height to meet the comfort requirements of Chinese code.
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