Patent Application
20150081256
This application is a continuation application of Patent Cooperation Treaty Application No. CN2013/073731, filed on Apr. 3, 2013, which claims priority to and the benefit of the filing of China Patent Application Ser. No. 201210095739.6, filed on Apr. 4, 2012, and the specification and claims thereof are incorporated herein by reference.
Not Applicable.
Not Applicable.
Not Applicable.
The present invention relates to a field of pre-stress steel structure, more particularly, relates to a method of designing a cable dome structure.
A cable dome structure relates to new material, new technology and new process, and has a reasonable stress characteristics and high structure efficiency. Thereby, the cable dome structure is one of modern architecture systems that can epitomize advanced material, design and construction technology level in modern architecture.
As shown in
In the prior art, the design of the cable dome structure is only limited to an elastic design stage mainly comprising member elasticity bearing capacity design and small system deformation capacity design. During designing in the prior, however, it is still blind and random to determine design indexes of the cable dome structure.
According to an object of the present invention, there is provided a method of determining design indexes of a cable dome structure based on a bearing whole process. The bearing whole process means a whole process of gradually loading the structure from an initial state, where the structure bears only self weight and an initial prestressing force of cable, until the structure is damaged.
In an exemplary embodiment, based on load-mechanical response characteristics of three stages, ridge cable relaxation-ring cable yield-structure failure, in the cable dome bearing whole process, obtaining a system elastic bearing capacity coefficient, a system stable bearing capacity coefficient and a system deformation capacity coefficient. In this way, it provides scientific basis and method for determining the design indexes of the cable dome structure. Please be noted that the stage of ridge cable relaxation means a condition where a tension stressing force on the ridge cable is equal to 0 Mpa; the stage of ring cable yield means a condition where a stressing force on the ring cable without obvious yield point, for example, a high strength steel strand, goes beyond 0.8 times of the yield stressing force of it (please be noted that even if there is no obvious yield point, a nominal yield point also can be calculated), as for the ring cable with obvious yield point, it corresponds to an inflection point, for example, a point Py*=6.5 in
The present invention provides a method of designing a cable dome structure, wherein the cable dome comprising a ridge cable and a ring cable, and the method comprising steps of: gradually loading the cable dome in a computer simulation or a model test, so that the cable dome is subjected to a bearing whole process having three stages comprising a ridge cable relaxation, a ring cable yield and a structure failure.
According to an aspect of the present invention, the method comprising steps of:
(1) by taking the ridge cable relaxation as a determination condition, calculating a system elastic bearing capacity coefficient K;
(2) by taking the ring cable yield as a determination condition, calculating a system yield load coefficient Py* and a system yield deformation coefficient Dy*;
(3) by taking the structure failure as a determination condition, calculating a cable dome system failure load coefficient 13,, and a system ultimate deformation coefficient Du;
(4) obtaining a system strength safety coefficient λP , a system deformation ductility safety coefficient λD, a system deformation coefficient allowable value [D], and a load coefficient P[D] corresponding to the system deformation coefficient allowable value [D];
(5) calculating a system stable bearing capacity coefficient Pλ of the cable dome based on an expression: Pλ=min {Py*, Pu/λP, P[D]}, and calculating a system deformation capacity coefficient Dλ of the cable dome based on an expression:
D
λ=min{Dy*,Du/λD,[D]}.
According to another aspect of the present invention, the method comprising steps of:
(1) by taking the ridge cable relaxation as a determination condition, calculating a system elastic bearing capacity coefficient K;
(3) by taking the structure failure as a determination condition, calculating a cable dome system failure load coefficient Pu and a system ultimate deformation coefficient Du;
(4) obtaining a system strength safety coefficient λP, a system deformation ductility safety coefficient λD , a system deformation coefficient allowable value [D], and a load coefficient P[D] corresponding to the system deformation coefficient allowable value [D];
(5) calculating a system stable bearing capacity coefficient Pλ of the cable dome based on an expression: Pλ=min{Pu/λP,P[D]}; and calculating a system deformation capacity coefficient Dλ of the cable dome based on an expression: Dλ=min{Du/λD, [D]}.
Optionally, the above method may further comprise steps of:
(6) conducting a material mechanics test on the cable in laboratory to obtain an elastic modulus, a yield strength, a ultimate strength, and a linear expansivity of material, conducting a mechanics test on a joint of the cable and a cable clamp in laboratory to obtain a friction coefficient and a restraint stiffness of the joint;
(7) based on a computer simulation or a model test, obtaining a relation between a system load coefficient and a cable force in a bearing whole process and a relation between the system load coefficient and a system deformation capacity in the bearing whole process,
wherein:
in the step (1), based on a relation between the system load coefficient and a ridge cable stressing force, calculating the system elastic bearing capacity coefficient K;
in the step (2), based on a relation between the system load coefficient and a ring cable stressing force, calculating the system yield load coefficient Py* and the system yield deformation coefficient Dy*;
in the step (3), based on a relation between the system load coefficient and the system deformation capacity, calculating the cable dome system failure load coefficient Pu and the system ultimate deformation coefficient Du.
In an exemplary embodiment of the present invention, the cable dome structure bearing whole process analysis is achieved by a computer simulation analysis, and wherein based on a test result obtained in the step (6), setting the material model of the cable dome structure as a nonlinear model; based on the test result obtained in the step (6), considering an effect of a pre-stress loss of the cable and the cable clamp joint restraint stiffness in a calculation model, and considering the cable dome structure system geometrical nonlinearity in calculation; conducting the analysis in a soft ware of ANSYS, and adopting a nonlinear iteration strategy for the calculation. A calculation process matrix equation of the nonlinear iteration strategy is expressed as follows:
[Kn,iT]{Δui}={Fna}−{Fn,i}
wherein
[Kn,iT] is a tangential stiffness matrix of ith iteration step in nth load step;
{Fna} is a load vector of nth load step;
{Fn,i} is a restoring force vector of ith iteration step in nth load step;
{Δui} is a displacement increment of ith iteration step.
Alternatively, in the above method, during designing the cable dome structure, simultaneously controlling the system elastic bearing capacity coefficient K, the system stable bearing capacity coefficient Pλ and the system deformation capacity coefficient Dλ.
Alternatively, in the step (1) of the above method, gradually loading the cable dome structure until K times of design load is applied on the cable dome.
With the technology solution of the present invention, relations among parameters, such as a system stable bearing capacity, a system deformation capacity and cable stressing forces (for example, stressing forces in the ridge cable, the ring cable and the slope cable), in three stages comprising the ridge cable relaxation, the ring cable yield and the structure failure have been analyzed during designing the cable dome structure, that is, load-mechanical response characteristics of the three stages, ridge cable relaxation-ring cable yield-structure failure, in the cable dome bearing whole process is analyzed. In this way, it considers not only a basic safety design requirements on the cable dome structure, but also considers a safety margin beyond safety design standard. Furthermore, there is also provided a method of determining three control index coefficients for the cable dome structure system safety design based on the bearing whole process.
The above and other features of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:
Exemplary embodiments of the present disclosure will be described hereinafter in detail with reference to the attached drawings, wherein the like reference numerals refer to the like elements. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein; rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those skilled in the art.
The present invention provides a method of designing a cable dome structure. The cable dome comprises a ridge cable and a ring cable. The method comprises step of: gradually loading the cable dome in a computer simulation or a model test, so that the cable dome is subjected to a bearing whole process having three stages comprising a ridge cable relaxation, a ring cable yield and a structure failure.
In the present invention, different from the design in the prior art, relations among parameters, such as a system stable bearing capacity, a system deformation capacity and cable stressing forces (for example, stressing forces in the ridge cable, the ring cable and the slope cable), in three stages comprising the ridge cable relaxation, the ring cable yield and the structure failure have been analyzed during designing the cable dome structure, that is, load-mechanical response characteristics of the three stages, ridge cable relaxation-ring cable yield-structure failure, in the cable dome bearing whole process is analyzed. In this way, it considers not only a basic safety design requirements on the cable dome structure, but also considers a safety margin beyond safety design standard.
Hereafter, it will describe the method of designing the cable dome structure based on the bearing whole process with reference to
(1) by taking the ridge cable 2 relaxation as a determination condition, calculating a system elastic bearing capacity coefficient K.
(2) by taking the ring cable 3 yield as a determination condition, calculating a system yield load coefficient Py* and a system yield deformation coefficient Dy*. For example,
(3) by taking the structure failure as a determination condition, calculating a cable dome system failure load coefficient Pu and a system ultimate deformation coefficient Du. For example, based on the curve of
(4) obtaining a system strength safety coefficient λP, a system deformation ductility safety coefficient λD, a system deformation coefficient allowable value [D], and a load coefficient P[D] corresponding to the system deformation coefficient allowable value [D];
(5) calculating a system stable bearing capacity coefficient Pλ of the cable dome based on an expression: Pλ=min {Py*,Pu/λP,P[D]}, and calculating a system deformation capacity coefficient Dλ of the cable dome based on an expression:
D
λ=min{Dy*,Du/λD,[D]}.
Optionally, in a case where the ring cable does not have a yield point (or the yield point cannot be obtained), the above step (2) can be omitted. Correspondingly, in the step (5), the system stable bearing capacity coefficient Pλ of the cable dome is calculated based on an expression: Pλ=min{Pu/λP,P[D]}, and the system deformation capacity coefficient Dλ of the cable dome is calculated based on an expression: Dλ=min{Du/λD, [D]}.
The system stable bearing capacity coefficient Pλ, the system deformation capacity coefficient Dλ and the system elastic bearing capacity coefficient K may be used as three indexes of designing the cable dome structure.
Optionally, the above method may further comprise steps of:
(6) conducting a material mechanics test on the cable in laboratory to obtain an elastic modulus (Es), a yield strength (fy), a ultimate strength (fu), and a linear expansivity of material (a), conducting a mechanics test on a joint of the cable and a cable clamp in laboratory to obtain a friction coefficient (u) and a restraint stiffness (k) of the joint;
(7) based on a computer simulation or a model test, obtaining a relation between a system load coefficient and a cable force in a bearing whole process and a relation between the system load coefficient and a system deformation capacity,
wherein:
in the step (1), based on a relation between the system load coefficient and a ridge cable stressing force, calculating the system elastic bearing capacity coefficient K;
in the step (3), based on a relation between the system load coefficient and the system deformation capacity, calculating the cable dome system failure load coefficient Pu and the system ultimate deformation coefficient Du.
In an exemplary embodiment of the present invention, the cable dome structure loading whole process analysis is achieved by a computer simulation analysis, and wherein based on a test result obtained in the step (6), setting the material model of the cable dome structure as a nonlinear model; based on the test result obtained in the step (6), considering an effect of a pre-stress loss of the cable and the cable clamp joint restraint stiffness in a calculation model, and considering the cable dome structure system geometrical nonlinearity in calculation; conducting the analysis in a soft ware of ANSYS, and adopting a nonlinear iteration strategy for the calculation. A calculation process matrix equation of the nonlinear iteration strategy is expressed as follows:
[Kn,iT]{Δui}={Fna}−{Fn,i}
wherein
[Kn,iT] is a tangential stiffness matrix of ith iteration step in nth load step;
{Fna} is a load vector of nth load step;
{Fn,i} is a restoring force vector of ith iteration step in nth load step;
{Δui} is a displacement increment of ith iteration step.
Optionally, in the above method, during designing the cable dome structure, simultaneously controlling the system elastic bearing capacity coefficient K, the system stable bearing capacity coefficient Pλ and the system deformation capacity coefficient Dλ.
Optionally, in the step (1) of the above method, gradually loading the cable dome structure until K times of design load is applied on the cable dome.
Hereafter, it will further describe in detail the method and its application of the present invention by an engineering example.
Engineering example: cable dome structure engineering
Step (1):
conducting a material mechanics test on the cable in laboratory to obtain an elastic modulus Es=1.9×105 MPa, a (nominal) yield strength fy=1330 MPa, a ultimate strength fu=1670 MPa, and a linear expansivity α=1.2×10−5/, conducting a mechanics test on a joint of the cable and a cable clamp in laboratory to obtain a friction coefficient and a restraint stiffness of the joint, and 3% of loss is considered during calculation.
Step (2):
Conducting the cable dome structure bearing whole process analysis, and based on a test result in the laboratory, setting the material model of the cable dome structure as a nonlinear model; considering an effect of a pre-stress loss of the cable and the cable clamp joint restraint stiffness in a calculation model; and conducting the analysis in a soft ware of ANSYS, and adopting a nonlinear iteration strategy for the calculation.
Step (3):
Based on the calculation of the bearing whole process of step (2),
Based on the calculation of the bearing whole process of step (2),
Based on the bearing whole process analysis, it may obtain the system yield load coefficient Py*=6.5 and the system yield deformation coefficient Dy*=1/42 when the outer ring cable is yielded.
Taking the structure failure as the determination condition, based on the bearing whole process analysis, it may obtain the cable dome system failure load coefficient Pu=12 and the system ultimate deformation coefficient Du=1/13.
Step (4):
The system strength safety coefficient λP is set to be larger than or equal to 1.2 and less than or equal to 1.5. In this engineering example, the system strength safety coefficient λP is equal to 1.5. The system deformation ductility safety coefficient λD is set to be larger than or equal to 1.2 and less than or equal to 1.8. In this engineering example, the system deformation ductility safety coefficient λD is equal to 1.8. The system deformation coefficient allowable value [D] is set to be in a range of 1/30˜1/50. In this engineering example, the system deformation coefficient allowable value [D] is equal to 1/40. The load coefficient P[D] corresponding to the system deformation coefficient allowable value [D] is equal to 6.6.
Based on the indexes obtained in the above steps, it can obtain the system stable bearing capacity coefficient Pλ and the system deformation capacity coefficient Dλ:
P
λ=min{6.5, 8.2, 6.6}=6.5
D
λ=min{1/42, 1/21.42, 1/40}=1/42
In sum, it can obtain the method of designing the cable dome structure of this engineering example based on the bearing whole process, more particularly, the method of determining the design indexes of the cable dome structure. In this engineering example, the system elastic bearing capacity coefficient K is determined to be equal to 1.5, the system stable bearing capacity coefficient Pλ is determined to be equal to 6.5, system deformation capacity coefficient Pλ determined to be equal to 1/42.
Although several exemplary embodiments have been shown and described, it would be appreciated by those skilled in the art that various changes or modifications may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201210095739.6 | Apr 2012 | CN | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN13/73731 | Apr 2013 | US |
| Child | 14500185 | US |
