Test And Analysis Of Concrete Stress In Cable Saddle Zone Of Long-span Extra-dosed Cable-stayed Bridge In Railway

The extra-dosed cable-stayed bridge is a new type bridge which is originated from France.In the past more than 20 years,it has been greatly developed in China.The extra-dosed cable-stayed bridge is a bridge form which is between the continuous girder bridge form and the cable-stayed bridge form.The rigidity of beam is large.The structure form of combining its tower and beam is the mainly appearanced form,the beam and the cable bear the load at the same time.The cable of extra-dosed bridge is similar to the external prestressed beam of continuous bridge.Therefore,compared to the traditional cable-stayed bridge,the tower height of the extra-dosed cable-stayed bridge is smaller and its dynamic performance is good.The extra-dosed cable-stayed bridge has greater competitive advantage at the span between 100 to 300 metres.Different from the traditional cable-stayed bridge tower anchorage form,the extra-dosed cable-stayed bridge generally adopts the continuous anchorage form through the anchorage zone of the bridge tower,and the saddle adopts the layered saddle.Nowadays,there are two main forms of structure,the double sleeve and the wire split pipe.The double sleeve structure is widely used in the early extra-dosed cable-stayed bridge.But in the practise,it is found that the stress concentration in the bottom of the sleeve is obvious,the steel strand exists mutual extrusion,the construction is difficult to wear the cable,and the anticorrosion effect can not be checked.Compared with it,the structure of wire split pipe has improved these problems,and has been widely applied in the extra-dosed cable-stayed bridge recently.Takes the Jinsha River bridge in Panzhihua as the real project,this paper makes a comparative analysis on the measured stress data of the cable area of tower of the real bridge,and uses the finite element simulation method to explore the stress distribution the cable tower anchorage zone.The main contents include:1.Summarise the development and development trend of the extra-dosed cable-stayed bridge at home and abroad,research the current cable tower anchorage area develpoment and the main problems in this field.2.Summarise the unique structure and mechanical characteristics of the extra-dosed cable-stayed bridge in cable tower,main girder and stay cable compared with the traditional cable-stayed bridge.3.According to the real construction sequence of the project,carry out the static analysis of the finite element model of the full bridge bar system of Panzhihua Jinsha River bridge,and explore the most terrible load situation,and provide the load data for the local solid finite element analysis mode in the next step.4.Compares the application of double sleeve structure and the wire split pipe structure.Establish a 3D solid finite element analysis model of the bottom segment of Cable Tower Anchorage Zone.Compared with the actual bridge measurement data and the theoretical calculation results under different working conditions.Carried out to explore the stress distribution of the cable tower anchorage zonethe with simulation analysis under the most unfavorable load conditions.Finally,according to the distribution of concrete stress,give the suggestions of concrete reinforcement design for anchorage zone of tower.