| The oblique single-tower cable-stayed bridge has a unique and novel shape,reasonable structural force and good economic applicability,and has gradually attracted the attention of bridge designers.The inclined single-tower cable-stayed bridge is a statically indeterminate structure for many times.During the construction,there are problems such as complex structural forces and easy cracks,which make the construction technology and construction control difficult.This paper takes a single-tower cablestayed bridge under construction as the engineering background,carries out research and analysis on the key construction technology and parameter sensitivity of the single-tower cable-stayed bridge,and obtains the following innovative results:(1)Use Midas Civil software to establish a finite element model of a single-tower cable-stayed bridge and analyze the construction mechanics.The analysis results show that: according to the traditional asynchronous construction of tower beams,the maximum tensile stress of the tower root during the construction phase is 2.25MPa(Allowable value 1.83MPa),it is very easy to cause the tower body concrete cracking;through multi-scheme construction mechanics analysis,it is proposed to adopt the synchronous construction technology of part of the tower and beam,that is,the upper tower column is divided into four parts for simultaneous construction of the tower and beam.At this time,the maximum tensile stress generated by the tower root during the construction stage is only 0.67 MPa,which can effectively prevent the tower body concrete from cracking.(2)The leaning tower body is constructed by cast-in-place supports,and the plane convergent force system is used to conduct mechanical analysis of the tower body structure,and the structural force characteristics of each construction stage are obtained,and the support removal timing is optimized accordingly.The results show that after the crown of 29# tower is capped,the support is removed.After the timing of removal is optimized,the compressive stress reserve at the outer edge of the tower root in the bridge state increases to 4.46 MPa,and the angle between the resultant force and the axis of the inclined tower decreases to 0.45°.The optimization of the timing of demolition can effectively prevent the tower roots from generating large tensile stress during the construction and use stages,avoid cracking of the tower body concrete and reduce subsequent maintenance costs.At the same time,the operation phase of the structure after the optimization of the timing of demolition was checked,and the results of the check were all in line with the requirements of the specification.(3)Midas Civil finite element software is used to check the strength and stability of the vertical temporary support structure of the tower body,and the Ansys finite element software is used to check the strength and stability of the locally supported beam section.The results show that the maximum combined stress of the vertical support is 238.9MPa,the minimum safety factor of the vertical support stability is 5.834,the maximum compressive stress of the support beam section is 13.73 MPa,and the vertical support structure and the support beam section meet the requirements of the specification.(4)The bulk density of the leaning tower,the bulk density of the main girder,the stiffness of the cable,the stiffness of the main girder,the climbing form load,the crane load,the ballast load,the temperature change and the change in the position of the cable anchor point are selected as the influence on the structural force and use of the bridge.For sensitive parameters of performance,the single variable control method is used for sensitivity analysis and the impact results are normalized.The results show that the bulk density of the main girder,crane load and temperature changes have the most significant impact on the structure of the bridge state,and the sensitive parameters should be strictly monitored during construction. |
