Disclosure of Invention
The invention aims to provide a method for calculating parameters of a cable-stayed bridge cable based on a graph method and a bisection method, which aims to overcome the defect that the initial value interval of the tangential slope of a beam-end cable is assumed in the calculation and solving process, and realize the effective calculation of the cable-stayed bridge cable parameters, which is simpler, more visual and more accurate.
The invention is realized in the way, and a method for calculating the parameters of a cable-stayed bridge cable based on a graph method and a bisection method comprises the following steps:
step (S1) of drawing a stay cable shape function by a graphic method
Finding a function image and
then determines the left and right two nearest to the intersection point
And assume the initial value
、
The upper and lower limits of the dichotomy are defined.
Step (S2) of taking the median of the upper and lower limits according to the characteristics of the dichotomy
And substituting the obtained value into a stay cable shape function to obtain
And then compared
And a magnitude relation of 0.
Step (S3), if
When the zero value is in the interval [ 2 ]
,
]In the meantime, make
=
. If it is
When the zero value is in the interval [ 2 ]
,
]In between, order
=
. The steps (S2) and (S3) are repeated.
Step (S4) when
(precision allowed value), let
Is a function
In the interval
,
]The zero solution of (a), is the slope of the a terminal,and solve the tension of the A end of the stay cable
T A Slope of B terminal
k B B end pull force
T B And total cable length
S。
In the above step, the function of the shape of the stay cable
Tension at end A
T A Slope of the B terminal
k B B end pull force
T B And total cable length
SRespectively as follows:
in the formula:
is a vertical component of the pulling force of the end A of the inhaul cable; ch () is a hyperbolic cosine function; arsh () is an inverse hyperbolic sine function; sh () is a hyperbolic sine function;
mass density of the guy cable unit length;
is the acceleration of gravity;
the A end of the stay cable is cut and pulled obliquely;
the horizontal projection distance of the two ends of the stay cable is shown;
is the vertical projection distance of the two ends of the inhaul cable.
The invention achieves the following beneficial effects: (1) in the aspect of the complexity of the method, the effective initial value range of the slope of the cable-stayed bridge cable can be visually and conveniently determined by a graph method; (2) in the aspect of timeliness of the method, the initial value range of the stayed cable of the cable-stayed bridge is determined by the graph method, so that the method is visual, convenient and effective, and the invalid initial range caused by any value is avoided, so that the processing time of the invalid initial range is removed, and the calculation efficiency of the method is improved; (3) in the aspect of the calculation precision of the method, the calculation precision can be controlled according to the actual engineering requirements, so that the calculation is more accurate and the efficiency is higher.
Drawings
FIG. 1 is a flow chart of the steps of a cable-stayed bridge cable parameter calculation method based on a graph method and a bisection method;
FIG. 2 is a guy cable layout drawing from pier No. 3 to pier No. 6 of the Changjiang river highway bridge of the copper rail in the embodiment of the invention
FIG. 3 shows an A1 cable k according to an embodiment of the present invention A -F relation diagram
FIG. 4 shows an A2 cable k according to the embodiment of the present invention A -F relation diagram
FIG. 5 shows an A3 cable k according to an embodiment of the present invention A -F relation diagram
FIG. 6 shows an A16 cable k according to the embodiment of the present invention A -F relation diagram
FIG. 7 shows a J1 cable k according to an embodiment of the present invention A -F relation diagram
FIG. 8 shows a J2 cable k according to the embodiment of the present invention A -F is offIs a drawing
FIG. 9 shows a J3 cable k according to the embodiment of the present invention A -F relation diagram
FIG. 10 shows a J16 cable k according to the embodiment of the present invention A -F relation diagram
FIG. 11 shows a J22 cable k according to the embodiment of the present invention A -F relation diagram
FIG. 12 shows a J26 cable k according to an embodiment of the present invention A -F relation diagram
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a method for calculating parameters of a cable-stayed bridge cable based on a graph method and a bisection method, which comprises the following steps as shown in figure 1:
step (S1) of drawing a stay cable shape function by a graphic method
Finding a function image and
then determines the left and right two nearest to the intersection point
And is assumed to be the initial value
、
The upper and lower limits of the dichotomy are defined.
In S1, according to the vertical component of the pulling force of the A end of the stay cable
Of the length of the cableMass density
Acceleration of gravity
Horizontal projection distance of two ends of the stay cable
And vertical projection distance
Drawing a stay cable shape function by a graph method
The graph can preliminarily visually and conveniently determine the effective initial value interval of the slope of the cable-stayed bridge cable by a graphic method
,
]This range will serve as the initial upper and lower limits of the dichotomy.
Step (S2) of taking the median of the upper and lower limits according to the characteristics of the dichotomy
And substituting the function into a stay cable shape function to obtain
And then compared
And a magnitude relation of 0.
In S2, the
And
respectively substituted into the stay cable shape function to obtain the corresponding
Value, i.e.
And
. Due to the fact that
,
Is to take two values around zero, and thus exists
。
Step (S3), if
When the zero value is in the interval [ 2 ]
,
]In between, order
=
. If it is
When the zero value is in the interval [ 2 ]
,
]In the meantime, make
=
. Repeating the steps (S2) and (S3).
Step (S4) when
(precision allowed value), let
I.e. as a function
In the interval
,
]The zero solution of (A) is the slope of the end A, and the tension of the end A of the stay cable is solved
T A Slope of B terminal
k B B end pull force
T B And total cable length
S。
The invention relates to an application case of a cable-stayed bridge cable parameter calculation method based on a graph method and a bisection method, which comprises the following steps: take the established highway bridge of the Yangtze river of the Yangshan mountain in Tongling City, anhui province as an example.
The Changjiang river highway bridge of Tongling was built in 1991 in 12 months and in 1995 in 26 months. The bridge is a prestressed reinforced concrete double-tower cable-side cable-stayed bridge, the total length of the bridge is 2592 meters, the total length of a main bridge is 1152m, 7 holes of 80+90+190+432+190+90+80m are continuously arranged, and the bridge consists of a double-tower cable-side prestressed concrete cable-stayed bridge with a main span of 432m and a continuous T-shaped rigid frame side span. The bridge tower adopts an H-shaped door type structure, the section of the box is a box, the height of the tower is 153.65m, the stay cables are arranged in a sector shape, each sector is provided with 26 pairs of cables, and the cable distance is 8 m. The arrangement of the guy cables on the piers No. 3 to No. 6 of the bridge is shown in figure 2. For comparative study, 10 cables A1, A2, A3, a16, J1, J2, J3, J16, J22 and J26 were selected for case testing, and the basic known parameters of each cable are shown in table 1.
TABLE 1 relevant parameters of each stay cable of the great bridge of the Changjiang river, copper Ling
Tab.1 The cable related parameters of Tongling Yangtze river highway bridge
TABLE 2 slope of each cable beam endk A Is taken as a value interval
Tab.2 The region taking value of beam-end slope k A
|
A1
|
A2
|
A3
|
A16
|
J1
|
J2
|
J3
|
J16
|
J22
|
J26
|
k A Value range
|
[4,4.5]
|
[2.5,3]
|
[2,2.5]
|
[0.5,1]
|
[4,4.5]
|
[2.5,3]
|
[2,2.5]
|
[0.5,1]
|
[0,1]
|
[0,1] |
In the process of solving the cable parameters, an initial value interval of the tangential slope of the cable at the beam end needs to be assumed, and iterative operation is carried out. In order to avoid invalid assumed intervals, a function graph of each stay cable line shape and the slope of the beam-end stay cable tangent line is drawn through a graphic method, and effective value intervals of the slope of each stay cable beam-end tangent line are determined. Because the included angle between the beam end guy cable and the horizontal direction is more than 0 degree, namely
>0. Only when the span of the cable-stayed bridge reaches 10000m, the tangential slope of the cable at the beam end can be equal to zero. At present, the longest span of the cable-stayed bridge just breaks through kilometers but not reaches ten thousand meters, so that the cable-stayed bridge,
k A may take zero, i.e. a lower limit of
k A And =0. The upper limit value can be the slope of the chord line of the guy cable nearest to the bridge tower
=4.44, take 4.5. Because the closer to the guy cable of the bridge tower, the larger the slope of the tangent line of the beam end is, and the actual position of the guy cable can deviate from the chord line under the influence of gravity, the guy cable is more stable, and the guy cable is more stable and reliable in use
k A May be taken to be at an upper limit
k A =4.5, whose actual position is lower than the chord line. Using graphical means to draw the cords
k A The diagram F is shown in FIGS. 3 to 12, and the accurate bisection solution can be further carried out according to the diagram
The value interval of the tangent slope of each cable beam end is obtained, and the result is shown in table 2. The effective reduction of the value interval can reduce the iteration times of the bisection method and is beneficial to improving the calculation efficiency. Taking A1 cable as an example, the determination can be carried out by a graphic method
The range of the interval of the accurate solution is [4, 4.5 ]]. The method for calculating the parameters of the cable-stayed bridge cable based on the graph method and the bisection method can calculate 10
-3 Of precision
And the solution only needs to be iterated for 9 times. Therefore, the combination of the graph method and the dichotomy can not only improve the precision, but also control the iteration times of high-precision calculation, and effectively improve the calculation efficiency.
TABLE 3 static force solution of each stayed-cable of Changjiang river highway bridge in copper tomb
Tab.3 The static solution of each cable of Tongling Yangtze river highway bridge
Note: a is the target value, B is the calculated value of the existing method, and C is the calculated value of the method of the invention
TABLE 4 Beam endsTension forceT A Tension force of tower endT B
Tab.4 The beam-end tension T A and the pylons-end tension T B
Note: b is the calculated value of the existing method, and C is the calculated value of the method of the invention
The results of the calculation of the respective cable-stayed parameters of the cable-stayed bridge are shown in tables 3 and 4. Considering the influence of the table space, the case only carries out error comparison calculation on the slope of the beam end tangent in the table. From the calculation of the A-B error and the A-C error in Table 3, it can be seen that: the iteration method adopted by the existing method is used for solving the problem that the maximum error of the slope of the tangent line of the beam end is stay J22, the error value reaches 4.67%, the minimum error is stay J1, and the error is 0.41%. The maximum error value of the method is 0.05% of the stay J3, the error value is very small and can be almost ignored, and the minimum error reaches 0%, and the error of most stays is 0%. It can be seen that the graphic method adopted by the method of the invention is combined with the dichotomy, and the precision is very high. As can be seen from the error calculation in table 4: the beam end guy cable tension force of the existing method has a certain error with the beam end guy cable tension force calculated by the method, the maximum error of the beam end of the J22 guy cable is 2.27%, and the maximum error of the tower end is 5.41%, which is caused by the fact that the existing method has a large error in calculating the tangent slope of the beam end of the J22 guy cable. The existing method carries out iterative operation by selecting an initial value, and random selection of the initial value can make the iterative operation invalid or obtain a result with a large error to a certain extent, so the existing method has certain limitation and uncertainty.
The invention provides a cable-stayed bridge cable parameter calculation method based on a graph method and a dichotomy, which can avoid the random defect of an initial value interval of a cable-stayed bridge end cable tangent slope, draws a function graph of a cable line shape and the beam end cable tangent slope through the graph method, quickly determines an effective value interval from the graph, combines a dichotomy program, can more accurately solve the beam end cable tangent slope in a cable line equation, and further solves related cable parameters such as cable length, tower end cable tangent slope, beam end and tower end cable tension. The calculation result of the parameters of the stay cable of the bridge on the Yangtze river highway by the method shows that the calculation of the parameters of the stay cable of the bridge based on the graph method and the bisection method is simpler, more visual and more accurate. In addition, the method can also control the calculation precision according to the actual engineering requirements, so that the calculation is more accurate and the efficiency is higher.
The above description is intended to be illustrative of the preferred embodiment of the present invention and should not be taken as limiting the invention, but rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.