LU502793B1 - A Design Method of A Bifurcated Tree-Like Arc Gate Support Arm - Google Patents

Abstract

The present invention belongs to the technical field of support arm structure, and discloses a design method of a bifurcated tree-like arc gate support arm. By solving the optimization model of the bifurcated tree-like support arm and dimensionless processing, the unit rigidity ratio of the trunk arm and the branch arms, and the ratio of the angle between the two branch arms to the central angle of the arc gate are given. The unit rigidity ratio of the trunk arm to the first branch arm and that of the trunk arm to the second branch arm are both 5.67. The length ratio of the branch arm to the second branch arm is 1.02. The section height ratio and thickness ratio of the trunk arm to the first branch arm are 1.805 and 1.405, respectively. The section height ratio and thickness ratio of the trunk arm to the second branch arm are 1.805 and 1.405, respectively. At this time, the overall buckling load of the tree-like support arm structure is 2.50-4.34 times the buckling load of the two support arms, and the volume ratio of the structure is reduced by 37%-53%. The present invention has the lightest structure, the maximum overall buckling load, and the highest stability.

Description

A Design Method of A Bifurcated Tree-Like Arc Gate Support Arm

LU502793

Field of the Invention

The present invention belongs to the technical field of hydraulic arc gate support arm structure, in particular to a design method of a bifurcated tree-like arc gate support arm.

Background of the Invention

Due to large span, high gate or high water head, many problems such as heavy hydraulic steel gate, insufficient structural rigidity or poor support arm stability will occur in large-scale hydraulic steel gates. Various gate accidents showed that all gate failures are caused by support arm instability due to severe vibration, and the main reason is weak rigidity of support arm. Arc gate support arm is mainly used to bear the water load generated by the arc gate panel and is installed on the overflow dam section. The current "Design Code for Steel Gate in Water

Resources and Hydropower Projects" (SL74-2013) specifies that such large-scale arc gates with large gate height should adopt traditional three-support arm or two-support arm structural style.

Although the three-support arm structure has relatively large overall rigidity, it has poor stability and unreasonable dynamic properties under the condition of the same amount of materials, while the two-support arm structure in a longitudinal plane has low rigidity. To solve the problems of ensuring high overall rigidity, high stability, light weight, and flexible opening and closing of gates, the only method is to combine the advantages of simple-support arm and multiple-support arm structures and overcome their disadvantages to achieve the safety and economy of arc gates.

The "Design Code for Steel Gate in Water Resources and Hydropower Projects" (SL74-2013) recommends that the length of the cantilever of the main beam of main beam type arc gates be 0.2 times its span (i.e. a/l is 0.2). However, the layout in the code only considers the maximum bending strength of the main beam in full-closing condition rather than the influence of bending moment at the end of the support arm, while the bending moment at the end of the support arm determines the safety and economy of the support arm. A large number of design practices showed that steel gates mainly work under the conditions of full-closing at normal water level, and check flood instantaneous opening and gate full-opening from the viewpoint of structure stress.

To ensure the safety, economy and flexible operation of steel gates under these conditions, the gate structure arrangement must be optimized by multi-condition multi-objective overall optimization according to the current hydraulic gate specification.

To sum up, the problems existing in the prior art are as follows:

With the continuous emergence of high dams, large-scale hydraulic steel gates have been developed. However, due to large span, high gate or high water head, the use of the existing two- support arm structure often leads to heavy hydraulic steel gates, insufficient structure rigidity or poor support arm stability, resulting in damage to hydraulic steel gates, downstream people's life and property safety. In order to make up for these disadvantages of the traditional two-support arm structure, the design method of the bifurcated tree-like arc gate support arm is proposed. The, 502793 bifurcated tree-like arc gate support arm designed by this method has the advantages of material saving and high stability, which can effectively solve the contradiction between large rigidity, high stability and light weight of the existing large arc gates.

Summary of the Invention

To solve the problems existing in the prior art, the present invention provides the design method of the bifurcated tree-like arc gate support arm.

The present invention is realized by providing the design method of the bifurcated tree-like arc gate support arm, wherein the design method of the bifurcated tree-like arc gate support arm comprises: by establishing the optimization model of the bifurcated tree-like support arm and dimensionless processing of free variables that satisfy various constraints, the unit rigidity ratio of the trunk arm to the branch arms, and the ratio of the angle between the two branch arms to the central angle of the arc gate are given; the ratio of the angle between the first branch arm and the second branch arm to the central angle of the arc gate is 1.98. The unit rigidity ratio of the trunk arm to the first branch arm and that of the trunk arm to the second branch arm are both 5.67. The length ratio of the branch arm to the first branch arm and that of the branch arm to the second branch arm are both 1.02. The section height ratio and thickness ratio of the trunk arm to the first branch arm are 1.805 and 1.405, respectively. The section height ratio and thickness ratio of the trunk arm to the second branch arm are 1.805 and 1.405, respectively.

Further, the optimization model of the bifurcated tree-like arc gate support arm is solved:

The optimization object is: { ] f. | min { Le x

Cr

The constraint is: fe, = [o]

SE. qi

Ae <[2] where Pcr is the critical buckling load of the overall structure of the bifurcated tree-like arc gate support arm (kN); V is the volume of the overall structure of the bifurcated tree-like arc gate support arm (m°); oi is the critical stress of the trunk arm and the branch arms (MPa); [0] is the allowable stress of the trunk arm and the branch arms (MPa); Amax is the maximum flexibility of the trunk arm and the branch arms, and [A] is the allowable flexibility of the trunk arm and the branch arms.

Another object of the present invention is to provide a trunk arm arranged on the bifurcated 02793 tree-like arc gate support arm; one end of the trunk arm is connected with the first branch arm and the second branch arm, respectively; and the ends of the first branch arm and the second branch arm are welded to the main frame of the arc gate;

The ratio of the angle between the first branch arm and the second branch arm to the central angle of the arc gate is 1.98. The unit rigidity ratio of the trunk arm to the first branch arm and that of the trunk arm to the second branch arm are both 5.67. The length ratio of the branch arm to the first branch arm and that of the branch arm to the second branch arm are both 1.02. The section height ratio and thickness ratio of the trunk arm to the first branch arm are 1.805 and 1.405, respectively. The section height ratio and thickness ratio of the trunk arm to the second branch arm are 1.805 and 1.405, respectively.

The present invention has the following advantages and positive effects:

The present invention determines the reasonable positions of Points A and B in the transverse frame and longitudinal frame of the bifurcated support arm, respectively.

After the positions of Points A and B are determined, the dimensions of the reasonably- arranged bifurcated tree-like support arm are determined. By taking the section size, length and other parameters of the trunk arm, the first branch arm, and the second branch arm as the optimization variables, i.e. choosing the dimensions of each section of the trunk arm, the width and wall thickness of each section of the branch arms, and the length of the trunk arm and the branch arms as the design variables, ensuring that the trunk arm and the branch arms of the tree- like support arm are unstable at the same time, aiming at the highest overall structural stability and the lightest structure, and considering constraints such as strength, stiffness, and stability, the optimization model of the bifurcated tree-like support arm is established. It is designed for dimensionless processing of free variables that satisfy various constraints, and for optimization design by giving the unit rigidity ratio of the trunk arm to the branch arms, and the ratio of the angle between the two branch arms to the central angle of the arc gate. When the ratio of the angle between the two branch arms to the central angle of the arc gate is 1.98, the unit rigidity ratio of the trunk arm to the branch arms is 5.67, the length ratio of the branch arms to the trunk arm is 1.02, the section height ratio and thickness ratio of the trunk arm to the branch arms are 1.805 and 1.405, respectively, the objective function obtains the optimal value, that is, the bifurcated tree-like support arm structure has the lightest weight, the largest overall buckling load, and the highest stability. The overall buckling load of the tree-like support arm structure of the present invention is 2.50-4.34 times the buckling load of the two support arms, and the volume ratio of the structure is reduced by 37%-53%.

Brief Description of the Drawings LU502793

Fig.1 is a schematic diagram of the bifurcated tree-like arc gate support arm provided by one embodiment of the present invention.

In the picture: 1. Trunk arm; 2. The first branch arm; 3. The second branch arm; 4. Main frame of arc gate

Fig.2 is a diagram for determining the positions of Points A and B in the transverse frame plane provided by one embodiment of the present invention.

Fig.3 is a diagram for determining the positions of Points A and B in the longitudinal frame plane provided by one embodiment of the present invention.

Detailed Description of the Preferred Embodiment

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiment. It is to be understood that the specific embodiment described herein is used for illustrating the present invention only and is not intended to limit the present invention.

The principle of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiment.

The design method of the bifurcated tree-like arc gate support arm provided by the embodiment of the present invention comprises: by establishing the optimization model of the bifurcated tree-like support arm and dimensionless processing of free variables that satisfy various constraints, the unit rigidity ratio of the trunk arm to the branch arms, and the ratio of the angle between the two branch arms to the central angle of the arc gate are given; the ratio of the angle between the first branch arm and the second branch arm to the central angle of the arc gate is 1.98. The unit rigidity ratio of the trunk arm to the first branch arm and that of the trunk arm tothe second branch arm are both 5.67. The length ratio of the branch arm to the first branch arm and that of the branch arm to the second branch arm are both 1.02. The section height ratio and thickness ratio of the trunk arm to the first branch arm are 1.805 and 1.405, respectively. The section height ratio and thickness ratio of the trunk arm to the second branch arm are 1.805 and 1.405, respectively.

The principle of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiment.

Fig.1 shows that the bifurcated tree-like arc gate support arm provided by the embodiment of the present invention is provided with the trunk arm 1; one end of the trunk arm is connected with the first branch arm 2 and the second branch arm 3, respectively; and the ends of the first branch arm and the second branch arm are welded to the main frame 4 of the arc gate;

The determined positions of Points A and B in the transverse frame plane provided by the embodiment of the present invention are shown in Fig.2. In Fig.2, | indicates the length of the main beam, a indicates the length of the cantilever of the main beam, Point A is the connection 02793 point between the upper support arm and the main beam, and Point B is the connection point between the lower support arm and the main beam. To reasonably determine the length a of the cantilever, the "Design Code for Steel Gate in Water Resources and Hydropower Projects" (SL74- 5 2013) recommends that the length of the cantilever of the main beam of main beam type arc gates be 0.2 times its span (ie. a/l is 0.2). However, the layout in the code only considers the maximum bending strength of the main beam in the fully closed condition rather than the influence of the bending moment at the end of the support arm, while the bending moment at the end of the support arm determines the safety and economy of the support arm. À large number of design practices showed that steel gates mainly work under the conditions of full-closing at normal water level, and check flood instantaneous opening and gate full-opening from the viewpoint of structure stress. To ensure the safety, economy and flexible operation of steel gates under these conditions, the gate structure arrangement must be optimized by multi-condition multi-objective overall optimization according to the current hydraulic gate specification. To allow the positive bending moment at the mid-span of the main beam to be equal to the absolute value of the negative bending moment at the support, and the maximum value to be minimum under the conditions of fully-closing at normal water level, check water instantaneous opening and gate fully-opening, and obtain the cantilever length of the main beam and the unit rigidity ratio of the main frame, a multi-condition multi-objective overall optimization model is established to arrange the main frame of the arc gate. The established optimization model is shown in equation (1).

The optimization object is:

The constraint is: (&e[3 11] a e[o 0225]

Where Fo: and Fon are the gate lifting force of the gate hoist when the gate is fully-closed and fully-opened, respectively, A is the value range of the length a of the cantilever, and Ko is the unit rigidity ratio of the main beam to the support arm.

By solving the optimization model, the most reasonable structure of the main frame of the arc gate is: the length of the cantilever of the main beam upon dimensionless processing is a/l= 0.160, i.e. the reasonable positions of Points A and B in the transverse main frame of the arc gate are determined.

In order to reasonably arrange the longitudinal frame of arc gates, the current code in China recommends that it should be arranged according to the equal-loading principle, and also requires "minimize the bending moment of the support arm in the longitudinal frame plane so that the support arm is closer to the one-way eccentric compression member". Currently, the longitudinal 02793 frame of arc gates can be reasonably arranged by taking it as curved beam for direct calculation with the spatial finite element method. By calculation using the spatial finite element method, the results on the reasonable arrangement of the longitudinal frame of arc gate are: a, B and y are 0.317, 0.513 and 0.170 respectively, i.e. the reasonable positions of Points A and B in the longitudinal main frame of the arc gate are determined, as shown in Fig.3.

The present invention will hereinafter be further described in conjunction with the design method in the specific embodiment.

The reasonable arrangement of Points A and B in the transverse frame and longitudinal frame of the bifurcated support arm is determined, respectively.

Fig.2 is to determine the positions of Points A and B in the transverse frame plane.

Fig.3 is to determine the positions of Points A and B in the longitudinal frame plane. By optimizing the two parts, the positions of Points A and point B can be determined.

Then, the specific dimensions of the bifurcated tree-like support arm are determined through size and shape optimization.

Finally, the design method of reasonably arranged bifurcated tree-like support arm is obtained.

By taking the section size, length and other parameters of the trunk arm 1, the first branch arm 2, and the second branch arm 3 as the optimization variables, i.e. choosing the dimensions of each section of the trunk arm, the width and wall thickness of each section of the branch arms, and the length of the trunk arm and the branch arms as the design variables, ensuring that the trunk arm and the branch arms of the tree-like support arm are unstable at the same time, aiming at the highest overall structural stability and the lightest structure, and considering the constraints such as strength, stiffness, and stability, an optimization model of bifurcated tree-like support arm is established. It is designed for dimensionless processing of free variables that satisfy various constraints, and for optimization design by giving the unit rigidity ratio of the trunk arm to the branch arms, and the ratio of the angle between the two branch arms to the central angle of the arc gate. When the ratio of the angle between the two branch arms to the central angle of the arc gate is 1.98, the unit rigidity ratio of the trunk arm to the branch arms is 5.67, the length ratio of the branch arms to the trunk arm is 1.02, the section height ratio and thickness ratio of the trunk arm to the branch arms are 1.805 and 1.405, respectively, the objective function obtains the optimal value, that is, the bifurcated tree-like support arm structure has the lightest weight, the largest overall buckling load, and the highest stability.

Fig.2 is to determine the positions of Points A and B in the transverse frame plane.

Fig.3 is to determine the positions of Points A and B in the longitudinal frame plane. By optimizing the two parts, the positions of Points A and point B can be determined.

Then, the specific dimensions of the bifurcated tree-like support arm are determined through size and shape optimization.

Finally, the design method of well-arranged bifurcated tree-like support arm is presented. LU502793

The above descriptions are merely one preferred embodiment of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims (3)

CLAIMS LU502793

1. A design method of a bifurcated tree-like arc gate support arm, wherein the design method of the bifurcated tree-like arc gate support arm comprises: by establishing the optimization model of the bifurcated tree-like support arm and dimensionless processing of free variables that satisfy various constraints, the unit rigidity ratio of the trunk arm to the branch arms, and the ratio of the angle between the two branch arms to the central angle of the arc gate are given; wherein — the ratio of the angle between the first branch arm and the second branch arm to the central angle of the arc gate is 1.98; — the unit rigidity ratio of the trunk arm to the first branch arm and that of the trunk arm to the second branch arm are both 5.67; — the length ratio of the branch arm to the first branch arm and that of the branch arm to the second branch arm are both 1.02; — the section height ratio and thickness ratio of the trunk arm to the first branch arm are

1.805 and 1.405, respectively; and — the section height ratio and thickness ratio of the trunk arm to the second branch arm are

1.805 and 1.405, respectively.

2. The design method of the bifurcated tree-like arc gate support arm according to claim 1, wherein the optimization model of the bifurcated tree-like arc gate support arm is: — the optimization object is: rl mind | : ! | \ y — the constraint is: a, <|o Six „33 (Ars = [A] Wherein: — Per is the critical buckling load of the overall structure of the bifurcated tree-like arc gate support arm (kN); — Vis the volume of the overall structure of the bifurcated tree-like arc gate support arm (md); — oi is the critical stress of the trunk arm and the branch arms (MPa); — [o] is the allowable stress of the trunk arm and the branch arms (MPa); — Amax IS the maximum flexibility of the trunk arm and the branch arms, and — [A] is the allowable flexibility of the trunk arm and the branch arms.

3. A bifurcated tree-like arc gate support arm designed by the design method of the bifurcated 02793 tree-like arc gate support arm according to claim 1, wherein — the bifurcated tree-like arc gate support arm is provided with a trunk arm; — one end of the trunk arm is connected with the first branch arm and the second branch arm, respectively; — the ends of the first branch arm and the second branch arm are welded to the main frame of the arc gate; — the ratio of the angle between the first branch arm and the second branch arm to the central angle of the arc gate is 1.98; — the unit rigidity ratio of the trunk arm to the first branch arm and that of the trunk arm to the second branch arm are both 5.67; — the length ratio of the branch arm to the first branch arm and that of the branch arm to the second branch arm are both 1.02; — the section height ratio and thickness ratio of the trunk arm to the first branch arm are

1.805 and 1.405, respectively; and — the section height ratio and thickness ratio of the trunk arm to the second branch arm are

1.805 and 1.405, respectively.