CN117807655A - Method for calculating load transverse distribution coefficient of precast slab girder bridge - Google Patents
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Abstract
The invention relates to the technical field of bridge structures, in particular to a method for calculating a load transverse distribution coefficient of a precast slab girder bridge, which comprises the following steps: firstly, calculating a rigidity correction factor m of a precast slab girder bridge, and then calculating a theoretical midspan load transverse distribution coefficient of a midspan sectionCalculating the theoretical support load transverse distribution coefficient of each precast slab with the support sectionCompared with the prior art, the method adopts a lever method to calculate the transverse load distribution coefficient of the support cross section and adopts a hinged plate girder method to calculate the transverse load distribution coefficient of the midspan cross sectionIn other words, the calculation method introduces the rigidity correction factor, and the rigidity correction factor considers the influence of bridge deck pavement on shearing resistance between adjacent precast slabs and the effect of transverse transmission force, so that the calculation of the transverse distribution coefficient of the bridge is more accurate, the bearing capacity of the bridge can be more accurately estimated, and the service life of the bridge is prolonged as much as possible.
Description
Technical Field
The invention relates to the technical field of bridge structures, in particular to a method for calculating a load transverse distribution coefficient of a precast slab girder bridge.
Background
The prefabricated slab girder bridge is a space integral stress structure formed by a plurality of slab girders, and is widely used in highway bridges in early stage due to simple structure, definite stress and convenient construction. The bridge is usually used for a bridge span of between 6 and 20m, a highway bridge with the span larger than 8m adopts a beam with a hollow section, and a highway bridge with the span of between 6 and 8m adopts a beam with a solid rectangular section. In order to ensure smooth road traffic, maintenance, repair, reinforcement and reconstruction of these bridges are required. When carrying out bearing capacity calculation, a designer can establish a space finite element model by means of finite element software to directly carry out simulation analysis, and can simplify the space structure into a planar rod piece to carry out approximate calculation by the concept of load transverse distribution coefficients. The simplified algorithm has clear mechanics principle and high calculation efficiency, and is a calculation method frequently selected by designers. The load transverse distribution coefficient is an important parameter for the load value of an automobile, and in the reinforcing and reforming process of some old precast slab girder bridges, the theoretical value of the unreasonable load transverse distribution coefficient is taken, so that the bearing capacity of bridge reinforcing calculation is too low, the bridge is removed and rebuilt, and certain social and economic losses are caused; or complex reinforcing measures are adopted for the bridge, so that the bridge is overwhelmed, and the service life of the bridge is shortened. Therefore, the scientific and reasonable load transverse distribution coefficient value method is researched, and the method has important theoretical and engineering significance for accurately evaluating the bridge bearing capacity.
In actual engineering, in order to prevent the direct wearing and tearing of wheel decking and the concentrated load of distribution wheel, set up bridge deck pavement layer on the decking, bridge deck pavement is in the same place with the girder connection, participates in the structural stress to a certain extent. If the finite element method is adopted for internal force analysis, a geometric model which counts in bridge deck pavement can be established, but the internal force calculation of each precast slab is inaccurate sometimes because of unreasonable interface bonding state simulation between adjacent slabs due to transverse connection rigidity; if a simplified algorithm is used for calculation, it is not explicitly specified in the specification which method to use for calculation. At present, when calculating the bearing capacity of a prefabricated slab bridge, a designer generally adopts a lever method to calculate the theoretical value of the transverse distribution coefficient of the section load of the support, and adopts a hinged slab beam method to calculate the theoretical value of the transverse distribution coefficient of the cross section load. The lever method is to consider the transverse structures such as bridge decks, diaphragm beams and the like as simply supported beams which are disconnected on the main beams and simply supported on the main beams, only vertical supports are born on the main beams, rotation is released, only beam plates with load action are stressed, and adjacent beam plates are not affected; the hinged plate girder method refers to a main girder as a plurality of plate girders which are hinged with each other in parallel transversely, and loads are transmitted to the rest of girder plates through shearing force among hinge joints to bear force together. However, the simplified algorithms do not consider the contribution of bridge deck pavement to the transverse transmission capacity of the bridge, and do not accord with the real stress condition of the bridge, so that the problem that the calculation of the automobile load is inaccurate and the bearing capacity of the bridge is difficult to evaluate accurately is caused.
Disclosure of Invention
The invention aims to solve the problems that in the prior art, the transverse load distribution coefficient of a support cross section is calculated by a lever method and the transverse load distribution coefficient of a cross section is calculated by a hinged plate girder method, the contribution of bridge deck pavement to shear resistance and bridge transverse force transmission between two adjacent precast slabs is not considered, the calculation of automobile load is inaccurate, and the bearing capacity of a bridge is difficult to evaluate accurately, and provides a method for calculating the transverse load distribution coefficient of a precast plate girder bridge.
In order to achieve the above object, the present invention provides the following technical solutions:
a method for calculating a load lateral distribution coefficient of a precast slab girder bridge, comprising the steps of:
s1, calculating a theoretical midspan load transverse distribution coefficient of a midspan section of the prefabricated slab girder bridge
S11, calculating a rigidity correction factor m of the prefabricated slab bridge:
s111, calculating a paving correction factor alpha and a span correction factor beta of the prefabricated slab girder bridge:
β＝(0.0034l 2 -0.1394l+1.9008)
in the formula, h 1 Thickness of paving bridge deck of prefabricated slab girder bridge, h 2 The hinge joint height of the precast slab girder bridge is l, and the calculated span of the precast slab girder bridge is l;
s112, calculating a rigidity correction factor m of the precast slab girder bridge:
m＝β(32.0030α 2 -22.3090α+5.1604)
the rigidity correction factor m is a correction parameter which introduces the influence of bridge pavement on the shear rigidity of two adjacent precast slabs and the transverse force transmission of the bridge;
s12, calculating the current unit load F 1 In the case of a precast slab bridge, the load of the i-th precast slab affects the line laterally, where i= {1,2 …, n }:
s121, calculating that under the condition of considering the rigidity correction factor m, unit load F is applied to the i th prefabricated plate 1 Shearing force g at each hinge joint;
s122, calculating the current unit load F 1 In the case of the kth prefabricated slab applied to the prefabricated slab bridge, the load eta obtained by the prefabricated slab of the ith slab ik Where k= {1,2 …, n }:
s123, according to the load eta obtained by the prefabricated plate of the ith plate ik Drawing a load transverse influence line of the i-th precast slab;
s13, arranging the vehicle load at the position of the least adverse load in the transverse direction, and calculating the theoretical mid-span load transverse distribution coefficient of the i-th precast slab with the mid-span section
Wherein eta is i Arranging the vehicle load according to the least adverse load in the transverse direction, wherein each wheel corresponds to an influence line longitudinal mark;
s2, calculating a theoretical support load transverse distribution coefficient of an ith prefabricated plate with a support section
And Q is a constant, and the calculation of the transverse distribution coefficient of the load of the prefabricated slab bridge is completed.
The calculated span l of the prefabricated slab bridge is in meters.
The cross section of the span is the cross section where one half of the mileage of the bridge is located, and the cross section of the support is the cross section where two ends of the bridge are located. Hinge joints are important parts of the upper structure of the prefabricated slab bridge, and connect the prefabricated slabs to form an integral upper partThe structure and plays a key role in transmitting the live load internal force among the precast slabs. The rigidity correction factor m is a factor taking the bridge deck pavement thickness h into consideration 1 Hinge joint height h 2 And a correction parameter for the calculated span l of the bridge. The bridge calculation span l is the distance between the centers of two adjacent supports of the bridge. The coefficients adopted in calculating the span correction factor beta and the rigidity correction factor m are obtained by fitting finite element analysis data and real bridge measurement data. Unit load F 1 When the rigidity correction factor m is applied to a certain precast slab, load is transmitted to the adjacent slab through shearing force, so that other precast slabs participate in stress, the rigidity correction factor m is introduced into a calculation formula of a hinged slab beam method, and the shearing force g at a hinge joint of the precast slab into which pavement influence factors are introduced can be calculated. And then obtaining the unit load F according to the calculated shearing force 1 And the load obtained by each prefabricated plate under the condition of acting on one prefabricated plate. The prefabricated panels are numbered as mid-span cross sections starting from one end to the opposite end. The 1 st prefabricated slab and the n th prefabricated slab refer to two prefabricated slabs at two sides of a prefabricated slab girder bridge, and the j th prefabricated slab refers to any one prefabricated slab except the 1 st prefabricated slab and the n th prefabricated slab. In the calculation process, the load bearing conditions of the 1 st prefabricated plate and the n th prefabricated plate are different, and the load bearing conditions of the 1 st prefabricated plate, the n th prefabricated plate and the j th prefabricated plate are also different. The hinge joint structure of the support section of the hinged plate girder bridge is the same as that of the cross section, so that the transverse load distribution rule of the support section is basically consistent with the trend of the cross section. So the theoretical mid-span load transverse distribution coefficientAnd the coefficient of the lateral distribution of the theoretical support load +.>Proportional calculation. And the transverse distribution coefficient of the load of the support cross section is larger than that of the cross section, so that the Q value in the step S3 is obtained by combining data measured by a plurality of groups of real bridges and data fitted by a precast slab bridge finite element model.
Compared with the prior art that the transverse load distribution coefficient of the support cross section is calculated by adopting a lever method and the transverse load distribution coefficient of the cross section is calculated by adopting a hinged plate girder method, the method introduces the rigidity correction factor, and the rigidity correction factor considers the influence of bridge deck pavement on the shear rigidity between adjacent precast slabs and the effect of transverse transmission force, so that the transverse distribution coefficient of the bridge is calculated more accurately, the bearing capacity of the bridge can be estimated more accurately, and the service life of the bridge is prolonged as far as possible.
Preferably, in step S121, when the unit load F 1 When applied to the first prefabricated panel, the shearing force g at each hinge joint meets the following formula:
wherein, gamma is the rigidity coefficient of the precast slab bridge, n is more than or equal to 3, n represents the number of precast slabs of the precast slab bridge, and m is the rigidity correction factor of the precast slab bridge.
In step S121, the value i=1 is taken.
Preferably, in step S122, when the unit load F 1 When the first prefabricated plate is applied, the load eta obtained by each prefabricated plate is divided i1 Satisfy the following formula, wherein eta i1 ＝η 1i ：
In step S122, the value i=1 to n is taken.
In step S121, when the unit load F 1 When applied to the n-th prefabricated panel, the shearing force g at each hinge joint meets the following formula:
wherein, gamma is the rigidity coefficient of the precast slab bridge, n is more than or equal to 3, n represents the number of precast slabs of the precast slab bridge, and m is the rigidity correction factor of the precast slab bridge.
In step S121, the value i=n is taken.
Preferably, in step S122, when the unit load F 1 When applied to the nth prefabricated panel, the load eta obtained by each prefabricated panel is divided in Satisfy the following formula, wherein eta in ＝η ni ：
In step S122, the value i=1 to n is taken.
Preferably, in step S121, in the case where i+.1 and i+.n, the shearing force g at each hinge joint satisfies the following equation:
wherein, gamma is the rigidity coefficient of the precast slab bridge, n is more than or equal to 3, n represents the number of precast slabs of the precast slab bridge, and m is the rigidity correction factor of the precast slab bridge.
In step S121, the unit load F is 1 Acting on any one of the prefabricated panels except the first and nth prefabricated panels.
Preferably, in step S122, in the case where i+.1 and i+.n, the load η obtained by each prefabricated panel is calculated ki Satisfy the following formula, wherein eta ki ＝η ik ：
In step S121, the unit load F is 1 Acting on any one of the prefabricated panels except the first and nth prefabricated panels.
In step S122, the unit load F is 1 Acting on any one of the prefabricated panels except the first and nth prefabricated panels.
Preferably, the stiffness coefficient γ of the prefabricated slab bridge is calculated in step S221 by the following formula:
wherein I is the bending rigidity of the cross section of the precast slab girder bridge, I T The torsional rigidity of the cross section of the precast slab girder bridge is represented by b, and the width of the cross section of the precast slab girder bridge is represented by b.
I T And the value of I is determined according to the actual situation. The rigidity coefficient gamma of the prefabricated slab girder bridge is calculated by adopting the calculation formula, and convenience and rapidness are realized.
Preferably, the value of the constant Q is obtained according to the ratio of the actual measurement value of the transverse distribution coefficient of the mid-span load to the actual measurement value of the transverse distribution coefficient of the support load.
Preferably, in step S3, Q is 1.15.ltoreq.Q.ltoreq.1.30.
Q is within the range, so that the safety of the bridge can be ensured as much as possible, and the transverse distribution coefficient of the load of the theoretical support cannot be causedToo large, so that as little material as possible is being constructed.
Preferably, calculating the theoretical mid-span load transverse distribution coefficient of the ith prefabricated plateAt the time, unit load F 1 Is arranged on the precast slab girder bridge according to the least adverse load in the transverse direction.
According to the position arrangement of the least adverse load, the bridge can be reliably used under various conditions, and the safety of the bridge is improved.
Preferably, the theoretical support load transverse distribution coefficient of the i th prefabricated plate is obtainedWhen the automobile load is arranged near the i th precast slab, the least adverse load is arranged transversely in such a way that all the automobile loads are arranged near the i th precast slabThe sum of the corresponding transverse distribution influence line vertical marks of the wheels is the largest.
Preferably, in step S222, it is assumed that the relative displacement of two prefabricated panels adjacent to each other on both sides of any one hinge joint is zero.
Compared with the prior art, the invention has the beneficial effects that:
1. the method for calculating the load transverse distribution coefficient of the precast slab girder bridge calculates a rigidity correction factor m, and the rigidity correction factor m considers the contribution of bridge deck pavement to the shear rigidity of hinge joints and the effect of transverse transmission force of bridge deck pavement, so that the load transverse distribution coefficient of the precast slab girder bridge can be calculated more accurately, the situation that potential safety hazards occur due to the fact that a reconstructed bridge is dismantled due to the fact that the bearing capacity of the bridge is evaluated too low or the bearing capacity of the bridge is evaluated too high is avoided, and the problems that in the prior art, the load transverse distribution coefficient of a support section is calculated by a lever method and the transverse distribution coefficient of a cross section is calculated by a hinged slab girder method are solved, the contribution of bridge deck pavement to shear resistance between two adjacent precast slabs and the transverse transmission force of the bridge are not considered, and the problem that the calculation of automobile load is inaccurate and the bearing capacity of the bridge is difficult to evaluate accurately is caused;
2. the method for calculating the load transverse distribution coefficient of the precast slab bridge is characterized in that the influence of bridge deck pavement on shear force at a hinge joint and transverse force transmission of a bridge is considered on the existing calculation method of hinge joint application, the load transverse distribution coefficient of a midspan section and a support section can be calculated, the calculation theory of the load transverse distribution coefficient of the precast slab bridge is perfected, and a basis is provided for reinforcement and extension of the precast slab bridge.
Description of the drawings:
FIG. 1 is a flow chart of a method for calculating the load lateral distribution coefficient of a precast slab girder bridge according to embodiment 1;
FIG. 2 is a load distribution diagram of a method for calculating a load lateral distribution coefficient of a precast slab girder bridge according to example 1;
FIG. 3 is a comparison of a measured value of a mid-span load lateral distribution coefficient and a calculated value of a mid-span load lateral distribution coefficient of a mid-span section;
FIG. 4 is a comparison of the measured values of the lateral distribution coefficients of the support load and the calculated values of the lateral distribution coefficients of the support load of the support cross section;
the marks in the figure: 1-prefabricated plate and 2-hinge joint.
Detailed Description
The present invention will be described in further detail with reference to test examples and specific embodiments. It should not be construed that the scope of the above subject matter of the present invention is limited to the following embodiments, and all techniques realized based on the present invention are within the scope of the present invention.
Example 1
As shown in fig. 1, a method for calculating a load lateral distribution coefficient of a precast slab girder bridge includes the steps of:
s1, calculating a theoretical midspan load transverse distribution coefficient of a midspan section of the prefabricated slab girder bridge
S11, fitting a rigidity correction factor m of the precast slab girder bridge according to actual measurement values of the mid-span load transverse distribution coefficients of the precast slab girder bridges:
s111, calculating a paving correction factor alpha and a span correction factor beta of the prefabricated slab girder bridge:
β＝(0.0034l 2 -0.1394l+1.9008)
in the formula, h 1 Thickness of paving bridge deck of prefabricated slab girder bridge, h 2 The height of the hinge joint 2 of the prefabricated slab bridge is l, the calculated span of the prefabricated slab bridge is expressed in meters, l is more than or equal to 8 and less than or equal to 20 in the embodiment, and the span correction factor is more than or equal to 0.166 and less than or equal to 0.395;
s112, calculating a rigidity correction factor m of the precast slab girder bridge:
m＝β(32.0030α 2 -22.3090α+5.1604)
the rigidity correction factor m is a correction parameter which introduces the influence of bridge pavement on the shear rigidity of two adjacent precast slabs 1 and the transverse force transmission of the bridge;
s12, calculating the current unit load F 1 In the case of a precast slab bridge, the load of the i-th precast slab (1) affects the line laterally, 19 slabs in this embodiment, where i= {1,2 …,19}:
s121, calculating a rigidity coefficient gamma of the prefabricated slab girder bridge;
wherein I is the bending rigidity of the cross section of the precast slab girder bridge, I T The torsional rigidity of the cross section of the precast slab girder bridge is shown, and b is the width of the cross section of the precast slab girder bridge;
s122, the main girder is regarded as a plurality of plate girders which are mutually hinged in parallel transversely by the traditional hinged plate girder method, and when a certain plate is provided with a unit load F 1 In operation, the load is transmitted only by the shearing force borne by the hinge joints 2 between the plates. According to the deformation coordination condition that the vertical relative displacement of two adjacent battens at the hinge joint 2 is zero, a regular equation is established, and the unit load F applied to the plate (1) is calculated 1 The shear force g at the hinge joint 2 of each prefabricated panel 1:
i. when the unit load F 1 When applied to the first prefabricated panel (1), as shown in fig. 2, the shearing force g at each hinge joint 2 satisfies the following formula:
in the formula, n is more than or equal to 3, j is more than or equal to 1 and less than or equal to 18, nineteen plates are arranged in the cross section of the span in the embodiment, j represents 18 hinge joints 2, and m is the rigidity correction factor of the precast slab girder bridge;
when the unit load F 1 Applied to the firstWhen the prefabricated plate 1 is manufactured, the shearing force g at each hinge joint 2 meets the following formula:
wherein, gamma is the rigidity coefficient of the precast slab girder bridge, j is more than or equal to 1 and less than or equal to 18, and n represents the number of precast slabs 1 of the precast slab girder bridge;
when i+.1 and i+.19, the shear g at each hinge joint 2 satisfies the following equation:
wherein, gamma is the rigidity coefficient of the precast slab girder bridge, j is more than or equal to 1 and less than or equal to 18, and n represents the number of precast slabs 1 of the precast slab girder bridge.
S123, calculating the current unit load F 1 In the case of the kth prefabricated slab 1 applied to the prefabricated slab bridge, the load η divided by the ith prefabricated slab 1 ik Where k= {1,2 …, n }:
i. when the unit load F 1 When applied to the prefabricated panel 1 of the number (1), the load of each prefabricated panel 1 is divided
η i1 Satisfy the following formula, wherein eta i1 ＝η 1i ：
When the unit load F 1 Applied to the firstWhen the prefabricated panels 1 are numbered, the loads obtained by the prefabricated panels 1 are respectively calculated
η i19 Satisfy the following formula, wherein eta i19 ＝η 19i ：
When a unit load F 1 Applied to non-No. 1 and non-No. 1When any prefabricated slab 1 is numbered, the load eta obtained by each prefabricated slab 1 is divided ki Satisfy the following formula, wherein eta ki ＝η ik ：
Wherein eta is 11 Is the unit load F 1 Applied to the plate (1), the load, eta, separated at the plate (1) 1j Is the unit load F 1 The load, eta, divided at the (1) th plate in the case of being applied at the j-th plate 119 Is the unit load F 1 Applied to the firstThe load obtained at the plate (1) under the condition of the plate;
s124, according to the load eta obtained by the i-th prefabricated plate 1 ik Drawing a load transverse influence line of the i-th precast slab 1;
s23, according to the deformation coordination condition that the vertical relative displacement at the hinge joint 2 is zero, sequentially solving the load transverse influence line coefficients of all the sheet beams, and finally according to all Liang Hezai transverse influence lines, arranging the vehicle load according to the transverse least favorable load to arrange the unit load F 1 The theoretical midspan load transverse distribution coefficient of each precast slab 1 arranged at the corresponding position and of the midspan section is calculated
Wherein eta is i The vehicle load is arranged according to the least adverse load in the transverse direction, and each wheel corresponds to an influence line longitudinal mark. In this step, the most unfavorable position of the vehicle load is taken according to the rule of the general rule for designing highway bridge and culvertTo obtain the corresponding influence line longitudinal mark eta of each wheel i The sum is the maximum;
s3, calculating a theoretical support load transverse distribution coefficient of a support section
And (5) finishing the calculation of the transverse distribution coefficient of the load of the precast slab girder bridge.
The factor 1.3 in step S3 results from a comparison of the actual measured support cross-section and the mid-span cross-section. In the embodiment, the actual measurement of the actual measurement value of the transverse distribution coefficient of the span load and the actual measurement value of the transverse distribution coefficient of the support load of the bridge with the bridge span of 8m, 13m and 20m and with the total 19 prefabricated slabs 1 is carried out under the working condition of a single vehicle:
when a single vehicle acts on the plates No. 2 and No. 4, the transverse load distribution coefficient of the plate No. 2 is obtained. From the above table, it can be seen that the transverse distribution coefficient of the load of the support cross section is integrally greater than the transverse distribution coefficient of the load of the cross section, and the transverse distribution coefficient of the load of the support cross section under individual working conditions is 1.27 times that of the transverse distribution coefficient of the load of the cross section, and the ratio is less than 1.15 under the other conditions, and is 1.3 times in the embodiment considering test errors and structural safety.
In this embodiment, theoretical calculation and actual measurement of the transverse distribution coefficient of each prefabricated slab are performed on the midspan section and the support section of a bridge with nineteen prefabricated slabs in total. Calculated span l=8m of bridge and thickness h of bridge deck pavement 1 =15 cm, hinge joint 2 height h 2 The span correction factor β=1.01, the pavement correction factor α=0.395, and the rigidity correction factor m=1.355. The actual measurement value of the load transverse distribution coefficient and the theoretical value of the load transverse distribution coefficient of the bridge are referred to the two tables below：
In this embodiment, a graph is also made by comparing the actual measurement value of the load transverse distribution coefficient and the calculation value of the load transverse distribution coefficient of the bridge, so that the fitting superiority of the calculation method is intuitively reflected, as shown in fig. 3 and 4. As can be seen from fig. 3 and fig. 4, the theoretical wheel value of the load transverse distribution coefficient calculated by adopting the modified hinge plate girder method is larger than the theoretical calculated value of the hinge plate method and smaller than the theoretical calculated value of the lever method, the actual measurement value of the load transverse distribution coefficient is well matched with the theoretical value of the load transverse distribution coefficient of the modified hinge plate girder method, and the peak value of the actual measurement load transverse distribution coefficient is smaller than the theoretical calculated value of the modified hinge plate method, so that the calculation of the load transverse distribution coefficient of the cross section by utilizing the modified hinge plate girder method is reasonable, the calculation of the load transverse distribution coefficient of the support section by utilizing the 1.3 times of the modified hinge plate girder method is beneficial to ensuring the safety of the prefabricated plate girder bridge, and the waste of construction materials caused by overlarge constant is avoided as much as possible.
And calculating a rigidity correction factor m of the precast slab girder bridge, wherein the coefficient of the formula is derived from the shear rigidity test and the actual measurement value of the load transverse distribution coefficient. In the shear rigidity test, a total of A, B, C and D groups of test pieces are provided, and the actual pavement thickness of each group of test pieces is different. In this test, the shear stiffness before failure of the single-sided hinge joint of the test pieces of the different groups was measured. And the standard shear rigidity is obtained by taking a test piece with the actual pavement thickness of 15cm as a standard. The shear stiffness of each group of test pieces is divided by the reference shear stiffness to obtain the shear stiffness ratio of each group. The results for each test piece are shown in the following table:
and then, determining a span correction factor beta by combining actual measurement values of the span load transverse distribution coefficients of the prefabricated slab bridges with the spans of 8m, 13m and 20m, and finally obtaining a rigidity correction factor m.
Example 2
Establishing a finite element model of a prefabricated slab girder bridge in midas Civil software, simulating the stress condition of a real bridge, and paving the bridge deck thickness h in the finite element model 1 Hinge h in finite element model =15 cm 2 The thickness of the cross beam in the finite element model is 5cm, the calculated span l of the bridge in the finite element model is 8m, and the total number of the prefabricated plates 1 is 19. Obtaining deflection values of all the plates under the load effect through finite element simulation analysis, and calculating according to the proportion of the deflection values of all the plates to the total deflection value to obtain the theoretical mid-span load transverse distribution coefficient of the i-th prefabricated plate 1And comparing with actual measurement values of the transverse distribution coefficients of the mid-span load measured by the real bridge, wherein the actual measurement values are shown in the following table:
when a single vehicle acts on the plates No. 2 and No. 4, the transverse load distribution coefficient of the plate No. 2 is obtained. From the above table, it can be seen that the theoretical mid-span load transverse distribution coefficientAre larger than the actual measurement value of the transverse distribution coefficient of the mid-span load measured by the real bridge, and are beneficial to improving the safety of the bridge. When a single vehicle is acting on the first prefabricated panel 1 and the first +.>When the block precast slab 1 is used, the rigidity is suddenly changed because the action position of the vehicle load is close to the junction of the new bridge and the old bridge, so that the simulation deviation is large. Except when a single vehicle is acting on the first prefabricated panel 1 and the first +.>In the case of prefabricated panels 1, the theoretical mid-span load transverse distribution coefficient +.>The deviation of the actual measurement values of the load transverse distribution coefficients of the midspan is smaller than 15%, so that the method for calculating the load transverse distribution coefficients of the precast slab bridge as in the embodiment 1 can reflect the distribution rule of the load transverse distribution coefficients of the precast slab bridge.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. A method for calculating a load transverse distribution coefficient of a precast slab girder bridge, comprising the steps of:
s1, calculating a theoretical midspan load transverse distribution coefficient of a midspan section of the prefabricated slab girder bridge
S11, calculating a rigidity correction factor m of the prefabricated slab bridge:
s111, calculating a paving correction factor alpha and a span correction factor beta of the prefabricated slab girder bridge:
β＝(0.0034l 2 -0.1394l+1.9008)
in the formula, h 1 Thickness of paving bridge deck of prefabricated slab girder bridge, h 2 The height of a hinge joint (2) of the precast slab girder bridge is l, and the calculated span of the precast slab girder bridge is l;
s112, calculating a rigidity correction factor m of the precast slab girder bridge:
m＝β(32.0030α 2 -22.3090α+5.1604)
the rigidity correction factor m is a correction parameter which introduces the influence of bridge pavement on the shear rigidity and the bridge transverse force transmission of two adjacent precast slabs (1);
s12, calculating the current unit load F 1 In the case of a precast slab bridge, the load of the i-th precast slab (1) affects the line laterally, where i= {1,2 …, n }:
s121, calculating the unit load F applied to the i th prefabricated plate (1) under the condition of considering the rigidity correction factor m 1 The shearing force g at each hinge joint (2);
s122, calculating the current unit load F 1 In the case of the kth prefabricated slab (1) applied to the prefabricated slab bridge, the load eta obtained by the ith prefabricated slab (1) ik Where k= {1,2 …, n };
s123, according to the load eta obtained by the i-th plate precast slab (1) ik Drawing a load transverse influence line of the i-th precast slab (1);
s13, arranging the vehicle load at the position of the least adverse load in the transverse direction, and calculating the theoretical mid-span load transverse distribution coefficient of the i-th precast slab (1) of the mid-span section
Wherein eta is i For loading the vehicle with least adverse load in transverse directionUnder the arrangement condition, the corresponding influence line longitudinal marks of each wheel;
s2, calculating a theoretical support load transverse distribution coefficient of the ith precast slab (1) with the support section
And Q is a constant, and the calculation of the transverse distribution coefficient of the load of the prefabricated slab bridge is completed.
2. A method for calculating a load transverse distribution coefficient of a precast slab girder bridge according to claim 1, wherein, in step S121, when the unit load F 1 When applied to the first prefabricated panel (1), the shearing force g at each hinge joint (2) meets the following formula:
wherein, gamma is the rigidity coefficient of the precast slab girder bridge, n is more than or equal to 3, n represents the number of precast slabs (1) of the precast slab girder bridge, and m is the rigidity correction factor of the precast slab girder bridge.
3. A method for calculating a load transverse distribution coefficient of a prefabricated slab bridge according to claim 2, wherein in step S122, when the unit load F 1 When applied to the first prefabricated panel (1), the load eta obtained by each prefabricated panel (1) i1 Satisfy the following formula, wherein eta i1 ＝η 1i ：
4. A method for calculating a load transverse distribution coefficient of a precast slab girder bridge according to claim 1, wherein, in step S121, when the unit load F 1 When applied to the n-th prefabricated slab (1), the shearing force g at each hinge joint (2) meets the following formula:
wherein, gamma is the rigidity coefficient of the precast slab girder bridge, n is more than or equal to 3, n represents the number of precast slabs (1) of the precast slab girder bridge, and m is the rigidity correction factor of the precast slab girder bridge.
5. The method for calculating a load transverse distribution coefficient of a precast slab girder bridge as claimed in claim 4, wherein, in step S122, when the unit load F 1 When applied to the nth prefabricated panel (1), the load eta obtained by each prefabricated panel (1) is divided in Satisfy the following formula, wherein eta in ＝η ni ：
6. Method for calculating the load transverse distribution coefficient of a prefabricated slab bridge according to claim 1, characterized in that in step S121, in case i+.1 and i+.n, the shear g at each hinge joint (2) satisfies the following formula:
wherein, gamma is the rigidity coefficient of the precast slab girder bridge, n is more than or equal to 3, n represents the number of precast slabs (1) of the precast slab girder bridge, and m is the rigidity correction factor of the precast slab girder bridge.
7. A method for computing a prefabrication as in claim 6A method for transversely distributing coefficients of loads of slab-girder bridges is characterized in that in step S122, when i is not equal to 1 and i is not equal to n, the loads eta of the prefabricated slabs (1) are obtained ki Satisfy the following formula, wherein eta ki ＝η ik ：
8. A method for calculating the load transverse distribution coefficient of a precast slab girder bridge according to any one of claims 1 to 7, wherein the stiffness coefficient γ of the precast slab girder bridge is calculated in step S221 by the following formula:
wherein I is the bending rigidity of the cross section of the precast slab girder bridge, I T The torsional rigidity of the cross section of the precast slab girder bridge is represented by b, and the width of the cross section of the precast slab girder bridge is represented by b.
9. A method for calculating a load transverse distribution coefficient of a precast slab girder bridge according to claim 1, wherein the value of the constant Q is obtained according to a ratio of the measured value of the load transverse distribution coefficient in the midspan and the measured value of the load transverse distribution coefficient of the support.
10. A method for calculating a load transverse distribution coefficient for a precast slab bridge according to claim 9, wherein in step S3, Q is 1.15.ltoreq.q.ltoreq.1.3.
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| CN109933875A (en) * | 2019-03-01 | 2019-06-25 | 武汉理工大学 | A kind of bridge structure Transverse Distribution calculation method considering old bridge Stiffness degradation |
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