CN113849898A - Cable dome structure continuous collapse risk judgment method and system - Google Patents
Cable dome structure continuous collapse risk judgment method and system Download PDFInfo
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Abstract
The invention discloses a method and a system for judging continuous collapse risk of a cable dome structure. Loading an initial cable dome structure model, calculating a rod member importance coefficient, and judging the continuous collapse risk category of the removed rod member; (2) the rod pieces are normalized according to the importance coefficient and then are sorted, and the adjacent rod pieces with different continuous collapse risk categories are searched; (3) adjusting the cable dome structure model to enable the rod piece importance coefficients to change in the value range of the rod piece classification critical point, judging the continuous collapse risk category of the rod piece, and searching for rod piece importance coefficient values which can enable rod piece classification results to be different to serve as rod piece classification critical points; (4) and judging the type of the continuous collapse risk. The invention defines the failure mode and the collapse mechanism of the component, determines the importance coefficients of various components in the process of resisting continuous collapse as the determining factors of the risk of continuous collapse, and reduces the risk of continuous collapse as much as possible at lower calculation cost.
Description
Technical Field
The invention belongs to the field of civil engineering, and particularly relates to a method and a system for judging continuous collapse risk of a cable dome structure.
Background
The cable dome structure is a flexible structure system which is formed by stretching and is formed by taking a cable and a pressure rod as basic units. The high strength of the inhaul cable is fully utilized, and the structural rigidity distribution is optimized by adjusting the structural prestress distribution, so that the structure has the advantages of good bearing performance, strong spanning capability, light structure and the like, and is widely applied to actual engineering.
Meanwhile, due to the low redundancy of the structure, when the structure is subjected to sudden conditions such as wind and snow overload and explosion impact or other unexpected interferences, the structure is easy to collapse continuously. Therefore, the deep analysis of the continuous collapse resistance of the structure and the improvement of the continuous collapse damage resistance and the non-occurrence of the asymmetrical damage of the structure have important significance for further popularization and application.
The current structural continuous collapse research object mainly focuses on a frame structure system, relatively few researches on a space large-span structure are conducted, the main reason is that based on the general understanding that traditional space large-span structures such as net racks and net shells have high hyperstatic times, and the failure of a single rod piece is not enough to obviously weaken the bearing capacity of the whole structure. However, the cable dome structure is different from the traditional large-span structure with high-order hyperstatic components such as a net rack reticulated shell and the like, the redundancy rate is low, the cable dome structure is sensitive to accidental interference such as construction errors and the like, and collapse is easy to occur under the action of overload or accidental interference. Therefore, the progressive collapse mechanism analysis according with the self characteristics of the cable dome structure, the evaluation of the function of various rod pieces in the process of resisting the progressive collapse of the structure and the optimization design research based on the progressive collapse resistance of the structure need to be further developed. Students at home and abroad such as model peaks and the like adopt the techniques of living and dead units, instantaneous removal members, instantaneous loading methods and the like to simulate cable breakage, and analyze the internal force change and node displacement response of structural rods after various cable dome structures are subjected to local failure and cable breakage. The dynamic response and collapse processes of structures such as a cable tension structure, a beam string and the like after local failure or cable breakage are analyzed on the basis of ANSYS/LS-DYNA software in the continental gold Yu, the Yangtze peak and the like. In general, response analysis and collapse phenomenon research of internal force and displacement caused by local failure and cable breakage of a tension structure are gradually developed, but qualitative description based on cable relaxation and quit work, local large deformation and large displacement and the like is more realized, and collapse development mechanism is not deeply analyzed.
Disclosure of Invention
The invention provides a method for judging continuous collapse risks of a cable dome structure, aiming at judging the continuous collapse risk categories of various rod pieces in a cable dome structure model through the importance coefficients of the rod pieces, so that the cable dome structure is quickly and accurately optimized, the continuous collapse risks are reduced as far as possible, and the technical problem that the cable dome structure continuous collapse risks cannot be quickly and accurately judged in the prior art is solved.
To achieve the above object, according to one aspect of the present invention, there is provided a cable dome structure progressive collapse risk determination method, including the steps of:
(1) loading an initial cable dome structure model, calculating a rod piece importance coefficient of each type of rod piece, and judging the type of continuous collapse risk of removing a certain rod piece according to the continuous collapse area and the vertical node displacement after removing the certain rod piece;
(2) normalizing the rod pieces according to the rod piece importance coefficients obtained in the step (1), and then sequencing the rod pieces, and searching one or more groups of adjacent rod pieces with different continuous collapse risk categories;
(3) regarding at least one group of adjacent rods with different continuous collapse risk categories obtained in the step (2), taking the values of the importance coefficients of the rods as the upper limit and the lower limit of the value range of the rod classification critical point; adjusting the cable dome structure model to enable the rod piece importance coefficient of at least one rod piece in the group to change in the value range of the rod piece classification critical point, judging the continuous collapse risk category of the rod piece according to the continuous collapse area and the vertical node displacement after the rod piece is removed, and searching for the rod piece importance coefficient value which can just enable the rod piece classification results to be different to serve as the rod piece classification critical point;
(4) and (3) calculating a rod member importance coefficient of the target rod member for the cable dome structure model, and judging the continuous collapse risk category of the rod member by adopting the rod member classification critical point obtained in the step (3) according to the principle that the more important the rod member is, the larger the continuous collapse risk is.
Preferably, in the method for judging the risk of progressive collapse of the cable dome structure, the model of the cable dome structure in step (1) includes a topology of each rod member of the cable dome, a cross-sectional area parameter of each member, and a prestress parameter of each member.
Preferably, the method for judging the risk of progressive collapse of the cable dome structure comprises a rod member importance coefficient gamma of a rod member jjThe calculation is carried out according to the following method:
γj＝δj/dj
wherein, deltajFor the sum of squares of the displacement differences before and after removal of a certain rod j, d, of all nodes of the cable dome structurejCalculating the accumulated displacement of all nodes of the cable dome structure before removing a certain rod piece j according to the following method:
wherein the content of the first and second substances,
respectively calculating the displacement difference of the ith node before and after removing a certain rod piece j along the x, y and z directions according to the following method:
n is a junctionTotal number of construction nodes; (u)j)ix、(uj)iy、(uj)izAnd (u)j)′ix、(uj)′iy、(uj)′izThe displacement components of the structure in the three directions of x, y and z of the ith node before and after a certain rod piece j is removed are respectively shown.
Preferably, the method for judging the risk of progressive collapse of the cable dome structure normalizes the rod member importance coefficient, and the normalized rod member importance coefficient γj′The calculation is as follows:
γj′＝γj/∑j＝1γj。
preferably, in the cable dome structure progressive collapse risk judgment method, the progressive collapse risk categories are classified according to the following criteria:
when the continuous collapse area of the cable dome structure meets a first condition, recognizing that the cable dome is subjected to continuous collapse damage, and judging that the rod piece is a key component with the highest continuous collapse risk; the first condition is preferably that the maximum vertical node displacement of the cable dome is greater than 1/50 of the span and the failure area reaches 30% of the total planar area of the structure;
when the continuous collapse area of the cable dome structure meets a second condition, recognizing that the cable dome is damaged by local continuous collapse, and judging that the rod piece is an important component with higher risk of continuous collapse; the second condition is preferably that the maximum vertical nodal displacement of the cable dome is greater than 1/50 of the span but the failure area is less than 30% of the total planar area of the structure,
when the maximum vertical node displacement of the cable dome is smaller than 1/50 of the span, or when the maximum node displacement of the cable dome is larger than 1/50 of the span but the failure area does not reach 15% of the total plane area of the structure, the cable dome is determined not to have continuous collapse damage, and the rod piece is judged to be a common member with lower continuous collapse risk.
Preferably, the method for judging the risk of progressive collapse of the cable dome structure includes the following steps (2):
taking a common rod piece with the largest rod piece importance coefficient and an important component with the smallest rod piece importance coefficient as a first group of adjacent rod pieces with different continuous collapse risk categories; and taking the important rod piece with the largest rod piece importance coefficient and the key component with the smallest rod piece importance coefficient as a second group of adjacent rod pieces with different continuous collapse risk categories.
Preferably, in the method for judging the risk of progressive collapse of the cable dome structure, the step (3) of adjusting the cable dome structure model includes adjusting the cross-sectional area of the rod, adjusting the length of the rod, adjusting the prestress level of the cable dome structure, and adjusting the radius of an annular cable of the cable dome structure.
Preferably, in the method for judging the risk of progressive collapse of the cable dome structure, the step (3) of adjusting the cable dome structure model specifically includes:
calculating and analyzing the influence rule of each design parameter of the cable dome structure model on each rod piece importance coefficient, and adjusting each design parameter according to the influence rule of each design parameter on the rod piece importance coefficient according to the ascending or descending order of the influence degree; the design parameters of the cable dome structure model comprise the section area of the rod piece, the length of the rod piece, the prestress level and the radius of the circular cable.
Preferably, in the method for judging the risk of progressive collapse of the cable dome structure, the step (3) of searching for the rod piece importance coefficient values that can make the rod piece classification results different as the rod piece classification critical points specifically includes:
selecting one of the group of adjacent rods with different successive collapse risk categories as a reference rod, adjusting the cable dome structure model according to the ascending or descending order of the rod importance coefficients, changing the rod importance coefficients of the reference rod within the value range of the rod classification critical point, judging the successive collapse risk categories of the reference rod according to the successive collapse area and the vertical node displacement after the rod is removed, reducing the adjustment range to reversely adjust the rod importance coefficients of the reference rod when the risk categories of the rod are changed, and adjusting the rod importance coefficients of the reference rod until the difference of the rod importance coefficients of the reference rod is smaller than a preset difference threshold value when the successive collapse risk categories of the two adjacent reference rods are changed, so that the difference between the rod importance coefficient values of the reference rods when the successive collapse risk categories of the two adjacent reference rods are changed, and determining a rod classification critical point of the risk classification change.
According to another aspect of the invention, a cable dome structure continuous collapse risk judgment system is provided, which comprises a model loading module, a rod piece searching module, a rod piece classification critical point searching module and a continuous collapse risk judgment module;
the model loading module is used for loading an initial cable dome structure model, calculating a rod piece importance coefficient of each type of rod piece, judging the type of continuous collapse risk of removing a certain rod piece according to the continuous collapse area and the vertical node displacement after removing the certain rod piece, and submitting the rod piece importance coefficient and the type of the continuous collapse risk of the rod piece to the rod piece searching module;
the rod piece searching module is used for normalizing the rod pieces according to the rod piece importance coefficients thereof and then sequencing the rod pieces, searching one or more groups of adjacent rod pieces with different continuous collapse risk categories, and submitting the one or more groups of rod pieces and the importance coefficients thereof to the rod piece classification critical point searching module;
the rod piece classification critical point searching module is used for taking the values of the rod piece importance coefficients of at least one group of adjacent rod pieces with different continuous collapse risk categories obtained in the step (2) as the upper limit and the lower limit of the value range of the rod piece classification critical point; adjusting the cable dome structure model to enable the rod piece importance coefficient of at least one rod piece in the group to change in the value range of the rod piece classification critical point, judging the continuous collapse risk category of the rod piece according to the continuous collapse area and the vertical node displacement after the rod piece is removed, searching for the rod piece importance coefficient value which can just enable the rod piece classification results to be different to serve as the rod piece classification critical point, and submitting the rod piece classification zero boundary point to the continuous collapse risk judgment module;
and the continuous collapse risk judgment module is used for calculating a rod member importance coefficient of the cable dome structure model target rod member, and judging the continuous collapse risk category of the rod member by adopting the rod member classification critical point according to the principle that the more important the rod member importance is, the larger the continuous collapse risk is.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
the method determines the failure mode and the collapse mechanism, determines the importance coefficients of various components in the process of resisting continuous collapse as the determining factors of the risk of continuous collapse, and determines the influence rules of the design parameters such as the section of the rod, the structural shape and the like on the importance coefficients by exploring the influence rules of the design parameters such as the section of the rod, the structural shape and the like on the structural resistance to continuous collapse, improves the capacity of the cable dome structure for resisting continuous collapse, and assists in optimizing the design model of the cable dome structure. On one hand, the method determines and finds out the rule of influence of design parameters such as the section of a rod piece, the structural shape and the like on the structural continuous collapse resistance, so that an optimization direction is provided for a cable dome structure design model, and calculated amount is reduced, and on the other hand, the cable dome structure continuous collapse process is not required to be simulated repeatedly through large amount of calculation in the optimization process, so that the continuous collapse area after the rod piece is removed is calculated, and the continuous collapse type is judged.
Drawings
FIG. 1 is a schematic view of an initial cable dome structure model topology according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following 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. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention finds that the importance coefficient of the rod piece is a decisive factor of the continuous collapse risk of the cable dome structure, and can judge and remove the continuous collapse risk of the cable dome structure caused by various components through the evaluation of the importance coefficients of various rod pieces.
The invention provides a method for judging continuous collapse risk of a cable dome structure, which comprises the following steps:
(1) loading an initial cable dome structure model, calculating a rod piece importance coefficient of each type of rod piece, and judging the type of continuous collapse risk of removing a certain rod piece according to the continuous collapse area and the vertical node displacement after removing the certain rod piece;
the cable dome structure model comprises a topological structure of each rod piece of the cable dome, cross-sectional area parameters of each component and prestress parameters of each component;
rod importance coefficient γ of rod jjThe calculation is carried out according to the following method:
γj＝δj/dj
wherein, deltajFor the sum of squares of the displacement differences before and after removal of a certain rod j, d, of all nodes of the cable dome structurejThe displacement of all nodes of the cable dome structure before removing a certain rod piece j is calculated according to the following method:
wherein the content of the first and second substances,
respectively calculating the displacement difference of the ith node before and after removing a certain rod piece j along the x, y and z directions according to the following method:
n is the total number of the structure nodes; (u)j)ix、(uj)iy、(uj)izAnd (u)j)′ix、(uj)′iy、(uj)′izThe displacement components of the structure in the three directions of x, y and z of the ith node before and after a certain rod piece j is removed are respectively shown.
Preferably, the rod importance coefficient is normalized, and the normalized rod importance coefficient gammaj′The calculation is as follows:
γj′＝γj/∑j＝1γj。
the continuous collapse area is the horizontal projection area of the area enclosed by the failed rod piece; the vertical node displacement is the displacement of each node in the vertical direction under the action of load, and can be calculated through finite element analysis.
The progressive collapse risk categories are divided according to the following standards:
when the continuous collapse area of the cable dome structure meets a first condition, recognizing that the cable dome is subjected to continuous collapse damage, and judging that the rod piece is a key component with the highest continuous collapse risk; the first condition is preferably that the maximum vertical node displacement of the cable dome is greater than 1/50 of the span and the failure area reaches 30% of the total planar area of the structure;
when the continuous collapse area of the cable dome structure meets a second condition, recognizing that the cable dome is damaged by local continuous collapse, and judging that the rod piece is an important component with higher risk of continuous collapse; the second condition is preferably that the maximum vertical nodal displacement of the cable dome is greater than 1/50 of the span but the failure area is less than 30% of the total planar area of the structure,
when the maximum vertical node displacement of the cable dome is smaller than 1/50 of the span, or when the maximum node displacement of the cable dome is larger than 1/50 of the span but the failure area does not reach 15% of the total plane area of the structure, the cable dome is determined not to have continuous collapse damage, and the rod piece is judged to be a common member with lower continuous collapse risk.
(2) Normalizing the rod pieces according to the rod piece importance coefficients obtained in the step (1), and then sequencing the rod pieces, and searching one or more groups of adjacent rod pieces with different continuous collapse risk categories; the method specifically comprises the following steps:
taking a common rod piece with the largest rod piece importance coefficient and an important component with the smallest rod piece importance coefficient as a first group of adjacent rod pieces with different continuous collapse risk categories; and taking the important rod piece with the largest rod piece importance coefficient and the key component with the smallest rod piece importance coefficient as a second group of adjacent rod pieces with different continuous collapse risk categories.
(3) Regarding at least one group of adjacent rods with different continuous collapse risk categories obtained in the step (2), taking the values of the importance coefficients of the rods as the upper limit and the lower limit of the value range of the rod classification critical point; adjusting the cable dome structure model to enable the rod piece importance coefficient of at least one rod piece in the group to change in the value range of the rod piece classification critical point, judging the continuous collapse risk category of the rod piece according to the continuous collapse area and the vertical node displacement after the rod piece is removed, and searching for the rod piece importance coefficient value which can just enable the rod piece classification results to be different to serve as the rod piece classification critical point;
the adjusting the cable dome structure model preferably comprises adjusting the cross-sectional area of the rod piece, adjusting the length of the rod piece, adjusting the prestress level of the cable dome structure, and adjusting the circular cable radius of the cable dome structure; the method specifically comprises the following steps:
calculating and analyzing the influence rule of each design parameter of the cable dome structure model on each rod piece importance coefficient, and adjusting each design parameter according to the influence rule of each design parameter on the rod piece importance coefficient according to the ascending or descending order of the influence degree; the design parameters of the cable dome structure model comprise the section area of the rod piece, the length of the rod piece, the prestress level and the radius of the circular cable.
The method comprises the following steps of adjusting the cross-sectional area of a rod piece, adjusting the length of the rod piece, adjusting the prestress level of the cable dome structure, adjusting the parameters of a cable dome structure model such as the radius of a circular cable of the cable dome structure, and the like, wherein the influence rule of the importance coefficient of the rod piece of a specific category under the condition of model determination can be determined, and the importance coefficient of the rod piece can be positive correlation, negative correlation or positive correlation in a certain range and negative correlation in a certain range. Therefore, aiming at a specific model, the importance coefficient of the specific rod piece can be reduced according to the influence rule of the parameters of the cable dome structure model on the specific rod piece, so that the cable dome structure is optimized, and the continuous collapse risk is reduced.
The specific steps of searching the rod piece classification critical points are as follows:
selecting one of the group of adjacent rods with different successive collapse risk categories as a reference rod, adjusting the cable dome structure model according to the ascending or descending order of the rod importance coefficients, changing the rod importance coefficients of the reference rod within the value range of the rod classification critical point, judging the successive collapse risk categories of the reference rod according to the successive collapse area and the vertical node displacement after the rod is removed, reducing the adjustment range to reversely adjust the rod importance coefficients of the reference rod when the risk categories of the rod are changed, and adjusting the rod importance coefficients of the reference rod until the difference of the rod importance coefficients of the reference rod is smaller than a preset difference threshold value when the successive collapse risk categories of the two adjacent reference rods are changed, so that the difference between the rod importance coefficient values of the reference rods when the successive collapse risk categories of the two adjacent reference rods are changed, and determining a rod classification critical point of the risk classification change.
(4) And (3) calculating a rod member importance coefficient of the target rod member for the cable dome structure model, and judging the continuous collapse risk category of the rod member by adopting the rod member classification critical point obtained in the step (3) according to the principle that the more important the rod member is, the larger the continuous collapse risk is.
The following are examples:
a method for judging the risk of continuous collapse of a cable dome structure, which takes an inner Mongolian Gouyi flag national fitness and sports center roof as a judgment object, comprises the following steps:
(1) loading an initial cable dome structure model, calculating a rod member importance coefficient of each type of rod member, and judging the continuous collapse risk type of the rod member according to the continuous collapse area and the vertical node displacement after a certain rod member is removed;
the cable dome structure model comprises a topological structure of each rod piece of the cable dome, cross-sectional area parameters of each component and prestress parameters of each component; specifically, the method comprises the following steps:
the inner Mongolian Guyi flag national fitness sports center roof adopts a flexible cable rod tension structure, namely a rib ring type cable dome structure, the span is 71.2 meters, the rise is 5.5 meters, the rise-to-span ratio is about 1/13, the hoop is divided into 20 parts, and the design load is 0.4kN/m 2. The structure is provided with two ring cables, the center is provided with a tension ring, the whole structure is fixedly hinged on the peripheral rigid compression ring beam, the structure model, the plane and the section are shown in figure 1, wherein figure 1(a) is a structure model diagram, figure 1(b) is a structure plane diagram, figure 1(c) is a structure section and dimension diagram, the section parameters and the initial prestress of each component are shown in table 1, and the elastic moduli of the stay cable and the compression bar are respectively 160GPa and 206 GPa.
TABLE 1 initial model component parameters and initial prestress values
Table 1 Parameters and initial pre-stress ofinitial model elements
The analysis method comprises the following steps:
selecting and modeling units: based on the stress characteristics of cable and rod units in the cable-rod pretensioning structure, LINK167 and LINK160 units are respectively selected during analysis of Ansys/Ls-dyna software, and prestress is applied by defining offset, wherein the specific formula is as follows:
F＝K×max{ΔL，0.0}
K＝EA/(L0-offset)
wherein Δ L, L0The amount of change in the length of the rod and the initial length, respectively, E, A the modulus of elasticity and the cross-sectional area of the rod, and offset the amount of offset. For the LINK160 unit, a bilinear dynamic material model was used and the failure strain of the member was defined to be 0.01, i.e., if compressed during the analysisThe strain of the rod exceeds 0.01 and the rod is automatically removed from the structure.
Replacement and unloading of equivalent force: in order to take the influence of the initial state into consideration and eliminate the dynamic influence of the static load increase on the structure, the analysis is carried out by adopting a full-power equivalent load instantaneous unloading method, namely, a certain component in the structure is removed, the component is replaced by equivalent force, and then the equivalent force is unloaded, so that the dynamic response of the structure in the whole process of the component failure is ascertained. When the structure is analyzed by using equivalent force to replace a removal component, unloading equivalent force and the like, the replacing time, the duration and the unloading time of the general equivalent force are respectively 2 times, 20 times and 1/10 times of the natural vibration period of the residual structure. The overall process time of the equivalent force action is shown in table 2.
TABLE 2 schedule of the equivalent effects
Table 2 Equivalent force schedule
For the 13 types of rods in the initial model, the rod importance coefficient is calculated, and the rod importance coefficient gamma of the rod j is calculatedjThe calculation is carried out according to the following method:
γj＝δj/dj
wherein, deltajFor the sum of squares of the displacement differences before and after removal of a certain rod j, d, of all nodes of the cable dome structurejThe displacement of all nodes of the cable dome structure before removing a certain rod piece j is calculated according to the following method:
wherein the content of the first and second substances,
respectively calculating the displacement difference of the ith node before and after removing a certain rod piece j along the x, y and z directions according to the following method:
n is the total number of the structure nodes; (u)j)ix、(uj)iy、(uj)izAnd (u)j)′ix、(uj)′uy、(uj)′izThe displacement components of the structure in the three directions of x, y and z of the ith node before and after a certain rod piece j is removed are respectively shown.
Preferably, the rod importance coefficient is normalized, and the normalized rod importance coefficient gammaj′The calculation is as follows:
γj′＝γj/∑j＝1γj。
the dynamic response and collapse patterns of the structure after the removal of the rods were analyzed, taking the displacement response and collapse patterns of the structure after the removal of the representative rods, the outer ridge cables, as an example (table 3):
the progressive collapse risk categories are divided according to the standard:
the correlation between various rod piece importance coefficients and the importance types of the rod pieces and the structural collapse mode is proved by combining the continuous collapse standard of the U.S. specification UFC4-023-03 on the cable dome structure, and the result shows that the rod piece importance coefficients determine the structural collapse mode. (1) When the maximum vertical node displacement of the cable dome is greater than 1/50 of the span and the failure area reaches 30% of the total plane area of the structure, the cable dome is considered to be subjected to continuous collapse damage; (2) when the maximum vertical node displacement of the cable dome is larger than 1/50 of the span, but the failure area does not reach 30% of the total plane area of the structure, the cable dome is considered to be subjected to local continuous collapse damage; (3) the cable dome is considered to have not suffered a progressive collapse failure when the maximum vertical nodal displacement of the cable dome is less than 1/50 of the span, or when the maximum nodal displacement of the cable dome is greater than 1/50 of the span, but the failure area does not reach 15% of the total planar area of the structure.
According to the specification, the cable dome collapse modes after the removal of the rod member are divided into three modes of continuous collapse, partial continuous collapse and non-continuous collapse, and then the corresponding removal members are defined as key members, important members and general members, and the results are shown in table 3.
TABLE 3 collapse modes and rod importance analysis resulting from removing different rods
Table 3 Analysis of collapse mode and member importance caused by removing different members
(2) Sorting the rod pieces according to the rod piece importance coefficients obtained in the step (1), and searching one or more groups of adjacent rod pieces with different continuous collapse risk categories as shown in a table 3; specifically, the method comprises the following steps:
taking a common rod piece with the largest rod piece importance coefficient and an important component with the smallest rod piece importance coefficient as a first group of adjacent rod pieces with different continuous collapse risk categories; and taking the important rod piece with the largest rod piece importance coefficient and the key component with the smallest rod piece importance coefficient as a second group of adjacent rod pieces with different continuous collapse risk categories.
In this embodiment, two adjacent rod members with different categories of risk of progressive collapse are selected, that is:
a first group: a tension ring lower chord and a tension ring upper chord; the importance sequences of the rod pieces are adjacent, namely 10 and 11; the continuous collapse risk types are different and are respectively common components and important components;
second group: the tension ring is wound up and an inner ring cable is arranged; the importance sequences of the rod pieces are adjacent, namely 11 and 12; the progressive collapse risk categories are different, namely important components and key components.
(3) Regarding at least one group of adjacent rods with different continuous collapse risk categories obtained in the step (2), taking the rod importance coefficient values of the rods as the upper limit and the lower limit of the value range of the rod classification critical point respectively; adjusting the cable dome structure model to enable the rod piece importance coefficient of at least one rod piece in the group to change in the value range of the rod piece classification critical point, judging the continuous collapse risk category of the rod piece according to the continuous collapse area and the vertical node displacement after the rod piece is removed, and searching for the rod piece importance coefficient value which can just enable the rod piece classification results to be different to serve as the rod piece classification critical point;
and the adjustment of the cable dome structure model comprises the steps of adjusting the section area of the rod piece, adjusting the length of the rod piece, adjusting the prestress level of the cable dome structure and adjusting the radius of a circular cable of the cable dome structure.
In order to find out the influence rule of different parameters on the importance coefficient of the rod piece and the continuous collapse resistance of the structure, the invention further analyzes the structure response and the collapse mode under the action of different parameters such as the prestress level, the section of the member, the radius of the ring cable, the length of the compression bar and the like.
1. Level of prestress
Keeping other parameters of the structure unchanged, calculating the importance coefficient of each rod piece by respectively taking initial prestress levels of 0.8 time, 1.2 times and 1.5 times as the prestress levels, and finding out that: (1) the different levels of prestress affect the importance factors of the rods to different extents, with the greatest effect on the inner hoop cables. When the prestress level is multiplied from 0.8 to 1.5 times of the initial prestress, the importance coefficient of the inner ring cable is reduced from 0.24 to 0.1 by 13 percent, and the change amplitude of the importance coefficients of other rod pieces is not more than 10 percent. (2) The magnitude of the prestress level generally has little effect on the progressive collapse resistance of the structure.
2. Section of component
Keeping other parameters of the structure unchanged, taking the sectional areas of the members as 0.8 times, 1.2 times and 1.5 times of initial sectional areas respectively, calculating the importance coefficients of the rod pieces, and finding that: (1) the influence degree of different member sections on the importance coefficients of the rod pieces is different, wherein the influence on the inner ring cables is the largest, when the member sections are increased from 0.8 times to 1.5 times of the initial sections, the importance coefficients are increased from 0.22 to 0.24, the improvement is 9%, and the change range of the importance coefficients of other rod pieces is not more than 3%. (2) Overall, the rod section has little effect on the structure's resistance to progressive collapse.
3. Radius of the endless rope
Keeping other parameters of the structure unchanged, respectively taking the radius of the outer ring cable as 0.8 time and 1.2 times of the radius of the initial outer ring cable, keeping the internal force of the outer ring cable unchanged, calculating the importance coefficient of each rod piece, and finding out that: (1) the influence degree of the change of the radius of the outer ring cable on the importance coefficients of various rod pieces is different, wherein the influence on the upper chord of the tension ring is the largest, and when the radius of the outer ring cable is multiplied to 1.2 times from 0.8, the importance coefficient of the upper chord of the tension ring is increased to 0.16 from 0.13, and the amplification reaches 23 percent; and the importance coefficient of the inner lasso is reduced from 0.25 to 0.22 by 12 percent. The change range of the importance coefficients of other rod pieces is not large and is not more than 4%. (2) In general, the radius of the outer ring cable has little influence on the continuous collapse resistance of the structure. (3) Meanwhile, the research finds that the radius of the inner ring cable has little influence on the continuous collapse resistance of the structure.
4. Length of the compression bar
Keeping other parameters of the structure unchanged, adjusting the length of the outer pressure rod to be 0.8 time and 1.2 times of the initial length by adjusting the coordinate of the lower node of the outer pressure rod, keeping the initial internal force of the outer annular cable unchanged, and calculating the importance coefficient of each rod piece, wherein the influence of the change of the length of the outer pressure rod on the importance coefficients of various rod pieces is different, and when the length of the outer pressure rod is multiplied from 0.8 to 1.2 times, the importance coefficient of the outer annular cable is increased from 0.48 to 0.55, and the increase is 15%; the importance coefficient of the lower chord of the tension ring is obviously reduced from 0.058 to 0.035, and the reduction amplitude reaches 40%. (2) In general, the length of the outer pressure rod has a large influence on the importance coefficient of partial rods, but has a small influence on the collapse resistance of the whole structure. (3) Meanwhile, the research finds that the length of the medium-pressure rod has little influence on the continuous collapse resistance of the structure.
The search just enables the bar member importance values with different bar member classification results to be used as bar member classification critical points specifically as follows: for the first group: a tension ring lower chord and a tension ring upper chord; the importance coefficients of the rod pieces are respectively 0.033 and 0.15, and the value ranges of the classification critical points of the common rod pieces and the important rod pieces are determined as follows: [0.033,0.15].
The change laws of the importance coefficients of the tension ring lower chord member and the tension ring upper chord member along with the parameters such as the prestress level, the member section area, the outer ring cable radius, the inner ring cable radius, the outer pressure rod length, the middle pressure rod length and the like are analyzed, and the importance coefficients of the tension ring lower chord member are found to increase along with the increase of the prestress level, the reduction of the member section area, the increase of the outer ring cable radius, the increase of the inner ring cable radius, the reduction of the outer pressure rod length and the reduction of the middle pressure rod length, while the importance coefficients of the tension ring upper chord member increase along with the decrease of the prestress level, the increase of the member section area, the increase of the outer ring cable radius, the increase of the inner ring cable radius, the reduction of the outer pressure rod length and the increase of the middle pressure rod length.
Through optimization calculation of each parameter, the classification critical point of the common rod piece and the important rod piece is determined to be 0.08.
For the second group: the tension ring is wound up and an inner ring cable is arranged; the importance of the rod pieces is respectively 0.15 and 0.23, and the value ranges of the classification critical points of the important rod pieces and the key rod pieces are determined as follows: [0.15,0.23].
The change laws of the importance coefficients of the tension ring upper chord and the inner ring cord bar piece along with the parameters such as the prestress level, the bar piece section area, the outer ring cord radius, the inner ring cord radius, the length of an outer pressure bar, the length of a medium pressure bar and the like are analyzed, and the importance coefficients of the tension ring upper chord bar piece are found to increase along with the reduction of the prestress level, the increase of the bar piece section area, the increase of the outer ring cord radius, the increase of the inner ring cord radius, the reduction of the length of the outer pressure bar and the increase of the length of the medium pressure bar, while the importance coefficients of the inner ring cord piece increase along with the reduction of the prestress level, the increase of the bar piece section area, the reduction of the outer ring cord radius, the increase of the inner ring cord radius, the reduction of the length of the outer pressure bar and the reduction of the length of the medium pressure bar.
Through optimization calculation of each parameter, the classification critical point of the important rod piece and the key rod piece is determined to be 0.19.
(4) And (3) calculating a rod member importance coefficient of the target rod member for the cable dome structure model, and judging the continuous collapse risk category of the rod member by adopting the rod member classification critical point obtained in the step (3) according to the principle that the more important the rod member is, the larger the continuous collapse risk is.
Wherein, the importance coefficients of the rod pieces of the outer ring cable and the inner ring cable exceed 0.19, and the structure after the rod pieces are removed has great dynamic response and belongs to a key rod piece; the importance coefficient of the tension ring upper chord member is between 0.19 and 0.08, and the removal of the rod member can cause the structure to locally collapse, has great influence on the structure and belongs to an important rod member; the importance coefficients of other types of rod pieces are below 0.08, the influence on the structure is small when the rod pieces are removed, continuous collapse cannot be generated, and the rod pieces belong to common rod pieces.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A cable dome structure continuous collapse risk judgment method is characterized by comprising the following steps:
(1) loading an initial cable dome structure model, calculating a rod piece importance coefficient of each type of rod piece, and judging the type of continuous collapse risk of removing a certain rod piece according to the continuous collapse area and the vertical node displacement after removing the certain rod piece;
(2) normalizing the rod pieces according to the rod piece importance coefficients obtained in the step (1), and then sequencing the rod pieces, and searching one or more groups of adjacent rod pieces with different continuous collapse risk categories;
(3) regarding at least one group of adjacent rods with different continuous collapse risk categories obtained in the step (2), taking the values of the importance coefficients of the rods as the upper limit and the lower limit of the value range of the rod classification critical point; adjusting the cable dome structure model to enable the rod piece importance coefficient of at least one rod piece in the group to change in the value range of the rod piece classification critical point, judging the continuous collapse risk category of the rod piece according to the continuous collapse area and the vertical node displacement after the rod piece is removed, and searching for the rod piece importance coefficient value which can just enable the rod piece classification results to be different to serve as the rod piece classification critical point;
(4) and (3) calculating a rod member importance coefficient of the target rod member for the cable dome structure model, and judging the continuous collapse risk category of the rod member by adopting the rod member classification critical point obtained in the step (3) according to the principle that the more important the rod member is, the larger the continuous collapse risk is.
2. The method for determining the risk of progressive collapse of a cable dome structure according to claim 1, wherein the cable dome structure model in the step (1) comprises a topology of each rod piece of the cable dome, a cross-sectional area parameter of each component, and a prestress parameter of each component.
3. The cable dome structure progressive collapse risk assessment method of claim 1, wherein the rod importance coefficient γ of the rod jjThe calculation is carried out according to the following method:
γj＝δj/dj
wherein, deltajFor the sum of squares of the displacement differences before and after removal of a certain rod j, d, of all nodes of the cable dome structurejCalculating the accumulated displacement of all nodes of the cable dome structure before removing a certain rod piece j according to the following method:
i＝1，2，3，…，n
wherein the content of the first and second substances,
respectively calculating the displacement difference of the ith node before and after removing a certain rod piece j along the x, y and z directions according to the following method:
n is the total number of the structure nodes; (u)j)ix、(uj)iy、(uj)izAnd (u)j)′ix、(uj)′iy、(uj)′izThe displacement components of the structure in the three directions of x, y and z of the ith node before and after a certain rod piece j is removed are respectively shown.
4. The cable dome structure progressive collapse risk judgment method according to claim 3, wherein the rod member importance coefficient is subjected to normalization processing, and the normalized rod member importance coefficient γj′The calculation is as follows:
γj′＝γj/∑j＝1γj。
5. the cable dome structure progressive collapse risk judgment method according to claim 1, wherein the progressive collapse risk categories are classified according to the following criteria:
when the continuous collapse area of the cable dome structure meets a first condition, recognizing that the cable dome is subjected to continuous collapse damage, and judging that the rod piece is a key component with the highest continuous collapse risk; the first condition is preferably that the maximum vertical node displacement of the cable dome is greater than 1/50 of the span and the failure area reaches 30% of the total planar area of the structure;
when the continuous collapse area of the cable dome structure meets a second condition, recognizing that the cable dome is damaged by local continuous collapse, and judging that the rod piece is an important component with higher risk of continuous collapse; the second condition is preferably that the maximum vertical nodal displacement of the cable dome is greater than 1/50 of the span but the failure area is less than 30% of the total planar area of the structure,
when the maximum vertical node displacement of the cable dome is smaller than 1/50 of the span, or when the maximum node displacement of the cable dome is larger than 1/50 of the span but the failure area does not reach 15% of the total plane area of the structure, the cable dome is determined not to have continuous collapse damage, and the rod piece is judged to be a common member with lower continuous collapse risk.
6. The cable dome structure progressive collapse risk judgment method according to claim 1, wherein the step (2) is specifically as follows:
taking a common rod piece with the largest rod piece importance coefficient and an important component with the smallest rod piece importance coefficient as a first group of adjacent rod pieces with different continuous collapse risk categories; and taking the important rod piece with the largest rod piece importance coefficient and the key component with the smallest rod piece importance coefficient as a second group of adjacent rod pieces with different continuous collapse risk categories.
7. The cable dome structure progressive collapse risk assessment method of claim 1, wherein said adjusting of said cable dome structure model of step (3) comprises adjusting a cross-sectional area of said rod member, adjusting a length of said rod member, adjusting a prestress level of said cable dome structure, and adjusting a lasso radius of said cable dome structure.
8. The cable dome structure progressive collapse risk judgment method according to claim 7, wherein the adjusting of the cable dome structure model in the step (3) is specifically:
calculating and analyzing the influence rule of each design parameter of the cable dome structure model on each rod piece importance coefficient, and adjusting each design parameter according to the influence rule of each design parameter on the rod piece importance coefficient according to the ascending or descending order of the influence degree; the design parameters of the cable dome structure model comprise the section area of the rod piece, the length of the rod piece, the prestress level and the radius of the circular cable.
9. The cable dome structure progressive collapse risk judgment method according to claim 1, wherein the searching in step (3) just enables the rod piece importance coefficient values with different rod piece classification results to be taken as rod piece classification critical points specifically as follows:
selecting one of the group of adjacent rods with different successive collapse risk categories as a reference rod, adjusting the cable dome structure model according to the ascending or descending order of the rod importance coefficients, changing the rod importance coefficients of the reference rod within the value range of the rod classification critical point, judging the successive collapse risk categories of the reference rod according to the successive collapse area and the vertical node displacement after the rod is removed, reducing the adjustment range to reversely adjust the rod importance coefficients of the reference rod when the risk categories of the rod are changed, and adjusting the rod importance coefficients of the reference rod until the difference of the rod importance coefficients of the reference rod is smaller than a preset difference threshold value when the successive collapse risk categories of the two adjacent reference rods are changed, so that the difference between the rod importance coefficient values of the reference rods when the successive collapse risk categories of the two adjacent reference rods are changed, and determining a rod classification critical point of the risk classification change.
10. A cable dome structure continuous collapse risk judgment system is characterized by comprising a model loading module, a rod piece searching module, a rod piece classification critical point searching module and a continuous collapse risk judgment module;
the model loading module is used for loading an initial cable dome structure model, calculating a rod piece importance coefficient of each type of rod piece, judging the type of continuous collapse risk of removing a certain rod piece according to the continuous collapse area and the vertical node displacement after removing the certain rod piece, and submitting the rod piece importance coefficient and the type of the continuous collapse risk of the rod piece to the rod piece searching module;
the rod piece searching module is used for normalizing the rod pieces according to the rod piece importance coefficients thereof and then sequencing the rod pieces, searching one or more groups of adjacent rod pieces with different continuous collapse risk categories, and submitting the one or more groups of rod pieces and the importance coefficients thereof to the rod piece classification critical point searching module;
the rod piece classification critical point searching module is used for taking the values of the rod piece importance coefficients of at least one group of adjacent rod pieces with different continuous collapse risk categories obtained in the step (2) as the upper limit and the lower limit of the value range of the rod piece classification critical point; adjusting the cable dome structure model to enable the rod piece importance coefficient of at least one rod piece in the group to change in the value range of the rod piece classification critical point, judging the continuous collapse risk category of the rod piece according to the continuous collapse area and the vertical node displacement after the rod piece is removed, searching for the rod piece importance coefficient value which can just enable the rod piece classification results to be different to serve as the rod piece classification critical point, and submitting the rod piece classification zero boundary point to the continuous collapse risk judgment module;
and the continuous collapse risk judgment module is used for calculating a rod member importance coefficient of the cable dome structure model target rod member, and judging the continuous collapse risk category of the rod member by adopting the rod member classification critical point according to the principle that the more important the rod member importance is, the larger the continuous collapse risk is.
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| CN114564851A (en) * | 2022-04-28 | 2022-05-31 | 北京建工集团有限责任公司 | Method and system for selecting monitoring points of large-span truss sensor and computer equipment |
| WO2023093874A1 (en) * | 2022-07-27 | 2023-06-01 | 深圳市城市公共安全技术研究院有限公司 | Building collapse risk assessment method and apparatus, computer device, and storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114564851A (en) * | 2022-04-28 | 2022-05-31 | 北京建工集团有限责任公司 | Method and system for selecting monitoring points of large-span truss sensor and computer equipment |
| WO2023093874A1 (en) * | 2022-07-27 | 2023-06-01 | 深圳市城市公共安全技术研究院有限公司 | Building collapse risk assessment method and apparatus, computer device, and storage medium |
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