CN-121996870-A - Longitudinal pre-deflection calculation method for continuous box girder support of high-speed railway

CN121996870ACN 121996870 ACN121996870 ACN 121996870ACN-121996870-A

Abstract

The invention discloses a method for calculating longitudinal pre-deflection of a continuous box girder support of a high-speed railway, which is characterized in that the deflection of the support is mainly influenced by two factors, namely, the deflection of each pivot point caused by elastic deformation and shrinkage creep of a box girder, the deflection of each support is set as delta 2, namely, the deflection caused by the temperature difference of a box girder system, the pre-deflection of the corresponding support can be obtained by delta= - ([ delta ] 1+ [ delta ] 2), and the negative sign indicates that the pre-deflection of the support is set in the opposite direction of the calculated value, so as to compensate the deformation displacement of concrete caused by elastic deformation, shrinkage creep and temperature change. The calculation flow and the key parameter value standard are defined, the accurate and reliable calculation result of the support pre-deflection is ensured, the support installation quality is ensured, the later adjustment cost is reduced, the construction safety risk is reduced, and the technical support is provided for the continuous box girder engineering construction of the high-speed railway.

Inventors

YIN WEI
SHANG LONG
SHEN ZHENXIN
CHEN NANJUN
ZHANG JIANXIN
YAO FANFAN
WU BAOSONG
WANG PENGCHENG

Assignees

中交二航局第四工程有限公司

Dates

Publication Date: 20260508
Application Date: 20260112

Claims (9)

1. A method for calculating longitudinal pre-deflection of a continuous box girder support of a high-speed railway is characterized by comprising the following steps: The offset of the support is mainly influenced by two factors, namely, the first is delta 1, namely, the offset of each fulcrum caused by the elastic deformation and shrinkage creep of the box girder, and the second is delta 2, namely, the offset caused by the temperature difference of the box girder system; The pre-deflection of the corresponding support can be obtained by a formula delta= - (. DELTA.1+. DELTA.2), and the negative sign indicates that the support pre-deflection is set in the opposite direction of the calculated value, so as to compensate the deformation displacement of the concrete caused by elastic deformation, shrinkage creep and temperature change.
2. The method for calculating the longitudinal pre-deflection of the continuous box girder support of the high-speed railway is characterized in that the deflection caused by the temperature difference of a box girder system is far away from the fixed support when the closure temperature is equal to the design temperature, and is close to the fixed support when the closure temperature is equal to the design temperature.
3. The method for calculating the longitudinal pre-deflection of the continuous box girder support of the high-speed railway according to claim 1, wherein the deflection of each fulcrum caused by elastic deformation and shrinkage creep of the box girder is close to the fixed support in the deflection direction.
4. The method for calculating the longitudinal pre-deflection of the continuous box girder support of the high-speed railway according to claim 1 is characterized by comprising the following steps of determining the model and the position of the support, determining the parameters of closure temperature, calculating the key deflection and obtaining the final value of the pre-deflection.
5. The method for calculating longitudinal pre-deflection of the continuous box girder support of the high-speed railway, which is characterized in that the model and the position of the support are determined by selecting the arrangement of the support according to the Ag value of the peak value of the earthquake motion in engineering design parameters, defining the mounting pier numbers and the line sides of the fixed support and the movable support by combining design description, and determining the positions of the packing stone and the anchor bolt hole according to the structural layout of the support, wherein the undefined position is confirmed by a design contact list; The method comprises the steps of determining closure temperature parameters, namely designing closure temperature by adopting construction diagram description or design intersection definition value preferentially, and taking the annual average temperature of the engineering when no description exists; Calculating key offset, namely setting the offset caused by elastic deformation and shrinkage creep of the delta 1 box girder from a design description, wherein the directions are close to a fixed support, calculating the offset caused by temperature difference of a delta 2 system according to a formula delta 2 = alpha t l, wherein alpha is the linear expansion coefficient of concrete, delta t is the difference between the design and actual closure temperature, and l is the length of the girder from the center of the support to the center of the fixed support, and judging the offset direction according to the temperature difference; And obtaining final values of the pre-deflection, namely calculating the total pre-deflection through a formula delta= - (DELTA1 + DELTA 2) by taking vector characteristics of DELTA 1 and DELTA 2 into consideration, wherein positive values are correspondingly arranged in the forward direction, and negative values are correspondingly arranged in the reverse direction, so that the accurate compensation of the deformation displacement of the concrete is realized.
6. The method for calculating the longitudinal pre-deflection of the continuous box girder support of the high-speed railway, as set forth in claim 5, wherein the delta 1 is the deformation of the girder body of the continuous box girder concrete caused by elastic deformation and shrinkage creep caused by stress and self-characteristics, the deformation of the girder body synchronously influences the deformation of the support, further the upper basin of the support generates the influence of the deflection relative to the lower basin of the support, and the shrinkage creep direction of the concrete is generally unchanged and is displaced towards the direction close to the fixed support.
7. The method for calculating the longitudinal pre-deflection of the continuous box girder support of the high-speed railway according to claim 6, wherein the length of the girder body is contracted or stretched under the influence of shrinkage creep or temperature change of concrete, and the shrinkage or stretching of the girder body is basically reflected in the side span length to cause the enlargement or shrinkage of a girder seam of the side span of the continuous girder because the fixed support is arranged at the bridge pier position of the middle span and cannot undergo displacement deformation. In order to offset the deformation caused by the self characteristics of the concrete, the Liang Fengkuan degrees are ensured to meet the design requirement, and Liang Changjin rows are required to be compensated according to the pre-deflection of the beam end support in the side span straight line section cast-in-situ process.
8. The method for calculating the longitudinal pre-deflection of the continuous box girder support of the high-speed railway according to claim 7, wherein the shrinkage or elongation of the girder body caused by the temperature change of the girder body concrete is cyclically and reciprocally carried out along with the change of seasons in one natural year, the high-temperature period is a period of time in which the girder length is prolonged and the girder gap is reduced, the low-temperature period is a period of time in which the girder length is shortened and the girder gap is enlarged when the girder is contracted when the girder is cooled, and the delta 1 is a main value, the delta 2 is a secondary value and the delta is smaller.
9. The method for calculating the longitudinal pre-deflection of the continuous box girder support of the high-speed railway according to claim 8, wherein in the calculation method, all external environment conditions are ideal during calculation, a few deviations exist between the actual situation on site and the drawing theory, when the girder end length is compensated according to the delta 1 numerical value, the comprehensive consideration is needed according to the actual measurement data on site, and the rule is found in the lengthened data for many times by combining with the railway work acceptance condition, so that the final Liang Fengkuan degrees are controlled to be optimal within the error range of +/-2 cm of the design value.

Description

Longitudinal pre-deflection calculation method for continuous box girder support of high-speed railway Technical Field The invention relates to the technical field of high-speed railway bridge construction, in particular to a method for calculating longitudinal pre-deflection of a continuous box girder support of a high-speed railway. Background With the rapid development of high-speed railway construction, the continuous box girder structure is widely applied to inter-city high-speed railway engineering due to strong crossing capability. The support is used as a key connecting component of the upper and lower structures of the bridge, and accurate calculation of the pre-deflection is a core guarantee of the installation quality. At present, the traditional pre-deflection calculation lacks of detailed description of design reference files or specifications, relies on experience estimation of constructors, or takes partial influence factors into consideration for rough calculation, and a system and an accurate calculation system are not formed. The limitations of the traditional calculation mode of the longitudinal pre-deflection of the continuous box girder support of the high-speed railway are that 1, the traditional calculation has no unified standard and accurate algorithm, numerical deviation is easy to occur, the installation position of the support is inaccurate, the support is required to be lifted up to replace or the pre-deflection is regulated in the later stage, the workload is extremely large, and the construction progress is seriously influenced. 2. The comprehensive influence of key factors such as elastic deformation, shrinkage creep and system temperature difference is not comprehensively considered in the calculation process, or vector characteristic judgment errors of all the factors are caused, so that the stress state of the support is not in accordance with the design requirement, and even the railway opening operation safety is influenced. 3. The traditional calculation does not determine the determination standard of key parameters such as closure temperature, support model position and the like, and is easy to cause the calculation error of the pre-deflection quantity due to incorrect parameter values, so that the risk of construction quality is increased. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a longitudinal pre-deflection calculation method for a continuous box girder support of a high-speed railway, which ensures accurate and reliable support pre-deflection calculation results and ensures support installation quality. In order to solve the technical problems, the invention adopts the following technical scheme: the method for calculating the longitudinal pre-deflection of the continuous box girder support of the high-speed railway comprises the following steps: The offset of the support is mainly influenced by two factors, namely, the first is delta 1, namely, the offset of each fulcrum caused by the elastic deformation and shrinkage creep of the box girder, and the second is delta 2, namely, the offset caused by the temperature difference of the box girder system; The pre-deflection of the corresponding support can be obtained by a formula delta= - (. DELTA.1+. DELTA.2), and the negative sign indicates that the support pre-deflection is set in the opposite direction of the calculated value, so as to compensate the deformation displacement of the concrete caused by elastic deformation, shrinkage creep and temperature change. Further: The box girder system temperature difference-induced offset, when the closure temperature is higher than the design temperature, the offset directions are far away from the direction of the fixed support, and when the closure temperature is lower than the design temperature, the offset directions are close to the direction of the fixed support. The deflection amounts of all the fulcrums caused by the elastic deformation and the shrinkage creep of the box girder are close to each other in the direction of the fixed support. The calculation method comprises the steps of determining the model and the position of the support, determining the parameters of the closure temperature, calculating the key offset, and obtaining the final value of the pre-offset. The model and the position of the support are determined, namely the arrangement of the support is selected according to the Ag value of the peak value of the earthquake motion acceleration in engineering design parameters, the mounting pier numbers and the line side of the fixed support and the movable support are determined by combining design instructions, the positions of the anchor block and the anchor bolt hole are determined according to the structural layout of the support, and the undefined position is confirmed by a design contact list; The method comprises the steps of determining closure temperature parameters, namely designing closure temperatu