CN115924740A - Asynchronous lifting control method for large-span steel structure - Google Patents
Asynchronous lifting control method for large-span steel structure Download PDFInfo
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Abstract
The invention relates to the technical field of large-span steel structure integral lifting, in particular to a method for controlling asynchronous lifting of a large-span steel structure, which comprises the steps of establishing a model; adjusting the vertical constraint rigidity of the current hoisting point and each adjacent hoisting point, and a. If the maximum stress ratio of the member reaches a first threshold value, the vertical deformation difference of the current hoisting point and each adjacent hoisting point does not exceed a second threshold value and the super-extraction coefficient is not less than a third threshold value, taking the super-extraction coefficient as a preliminary super-extraction coefficient; b. if the maximum stress ratio of the member reaches a first threshold value, the vertical deformation difference between the current lifting point and each adjacent lifting point does not exceed a second threshold value, the super-lifting coefficient is smaller than a third threshold value, the third threshold value is used as a preliminary super-lifting coefficient, and the minimum vertical deformation difference is used as a super-lifting deformation limit value; c. and if the stress ratio of the member does not exceed the first threshold value, but the vertical deformation difference between the current lifting point and each adjacent lifting point exceeds a second threshold value, taking the minimum over-lifting coefficient as a preliminary over-lifting coefficient, and taking the second threshold value as an over-lifting deformation limit value.
Description
Technical Field
The invention relates to the technical field of large-span steel structure integral lifting, in particular to a method for controlling asynchronous lifting of a large-span steel structure.
Background
The integral lifting construction method is characterized in that the large-span structure is assembled into a whole on the ground and then lifted to a design position by using the hydraulic oil cylinder device, the integral lifting construction method has the advantages of high construction quality and high construction speed, and is widely applied to construction of structures such as a large-span grid structure, a reticulated shell structure, a truss structure and the like. Theoretically, because the large-span steel structure is a whole, each lifting point is synchronously lifted in the lifting process; however, the actual large-span steel structure integral lifting construction is a dynamic process, and the lifting may be asynchronous due to different flow rates of hydraulic cylinders of lifting points, different loosening degrees of steel strands, insufficient anchorage fastening degree and the like, so that a certain lifting point may be subjected to over-lifting or force unloading, the internal force of the structure may be redistributed, the stress of the structural member may be caused to exceed the elastic state, and even the local instability of the structure may be caused, and therefore asynchronous lifting analysis and control are required.
In the traditional lifting process, the asynchronous lifting control mode is that when the super lifting deformation of a certain point reaches 20mm or the super lifting force is 1.2 times of the synchronous lifting force, hovering and adjusting are carried out. However, the existing calculation analysis method cannot consider the whole dynamic change promotion process; different structural forms cannot be considered, and the sensitivity degrees of different lifting heights and different lifting points for asynchronous lifting of the structure are different; in addition, the influence of asynchronous lifting on each lifting point is not isolated, and each lifting point is controlled according to a traditional mode, so that potential safety hazards exist, and the construction efficiency is influenced by repeated hovering.
Disclosure of Invention
In order to solve the technical problems, the invention provides an asynchronous lifting control method for a large-span steel structure, and the specific technical scheme is as follows.
The asynchronous lifting control method for the large-span steel structure comprises the following steps:
establishing a fine analysis model of the lifting process of the large-span steel structure;
the control method for respectively determining each hoisting point based on the refined analysis model of the lifting process comprises the following steps:
adjusting the vertical constraint rigidity of the current hoisting point and each adjacent hoisting point, respectively processing the following steps,
a. if the maximum stress ratio of the member reaches a first threshold value, the vertical deformation difference between the current lifting point and each adjacent lifting point does not exceed a second threshold value, and the super-lifting coefficient of the current lifting point is not smaller than a third threshold value at the moment, and the super-lifting coefficient is taken as the initial super-lifting coefficient of the current lifting point to control the lifting of the current lifting point; the super lifting coefficient is the ratio of the asynchronous lifting force and the synchronous lifting force of the current lifting point;
b. if the maximum stress ratio of the member reaches a first threshold value, the vertical deformation difference between the current lifting point and each adjacent lifting point does not exceed a second threshold value, and the super-lifting coefficient is smaller than a third threshold value, continuously adjusting the rigidity of the current lifting point and each adjacent lifting point until the super-lifting coefficient of the current lifting point reaches the third threshold value, comparing the vertical deformation difference between the current lifting point and each adjacent lifting point to obtain a minimum vertical deformation difference, and controlling the lifting of the current lifting point by taking the third threshold value as a preliminary super-lifting coefficient and the minimum vertical deformation difference as a super-lifting deformation limit value;
c. and if the stress ratio of the member does not exceed the first threshold value, but the vertical deformation difference between the current lifting point and each adjacent lifting point exceeds a second threshold value, taking the minimum super-lifting coefficient in each adjacent lifting point as a preliminary super-lifting coefficient, and taking the second threshold value as a super-lifting deformation limit value of the current lifting point to control the lifting of the current lifting point.
Further, the control method for determining each hoisting point further comprises the following steps: after determining the initial super-lifting coefficient of each lifting point, correcting the super-lifting coefficients of other lifting points by taking one lifting point as a reference lifting point;
the process of correcting the super-lifting coefficient of a certain lifting point to be adjusted by taking a lifting point as a reference lifting point comprises the following steps: and enabling the reference lifting point to reach the corresponding preliminary super-lifting coefficient, adjusting the rigidity of the lifting point to be adjusted under the working condition until the rigidity reaches the corresponding preliminary super-lifting coefficient, and judging as follows:
d. if the maximum stress ratio in the member does not exceed the fourth threshold value, and the vertical deformation difference between the lifting point to be adjusted and the adjacent lifting point does not exceed the second threshold value or the lifting deformation limit value of the lifting point, no correction is carried out;
e. if the maximum stress ratio in the member exceeds a fourth threshold value, or the vertical deformation difference between the lifting point to be adjusted and the adjacent lifting point exceeds a second threshold value or the lifting point exceeding the lifting deformation limit value, or the reference lifting point exceeds a preliminary lifting coefficient, correcting the lifting point to be adjusted; the correction process comprises the following steps:
and adjusting the rigidity of the reference lifting point and the lifting point to be adjusted to enable the reference lifting point to reach the preliminary over-lifting coefficient, and simultaneously enabling the structural stress ratio to be a fourth threshold value or the deformation difference between the lifting point to be adjusted and the adjacent lifting point to just reach a second threshold value, and taking the over-lifting coefficient of the lifting point to be adjusted at the moment as the corrected final over-lifting coefficient.
Further, establishing a refinement analysis model of the lifting process of the large-span steel structure comprises:
respectively applying lateral constraint and vertical constraint to the simulation model according to the lifting height;
applying lateral restraint includes applying K at the drop point X ＝K Y ＝F zi A horizontal constraint of/l, where K X Constraint in the X direction, K Y Constraint in the Y direction, F zi The synchronous lifting force of the lifting point under the self-weight load of the lifting structure is represented by l, and the length of the steel strand from the lower lifting point of the steel strand to the top of the lifting device in the lifting process is represented by l;
applying vertical restraint includes applying K at the drop point Z ＝3F Zi E/f ptk l, where E is the modulus of elasticity of the steel strand, f ptk Is the standard value of the tensile strength of the steel strand.
Further, the synchronous lifting force F zi The determination process of (2) includes: applying elastic constraint at the lower lifting point of the simulation model, completely constraining the vertical deformation of the lower lifting point, and simultaneously applying K at the lower lifting point X ＝K Y And the horizontal constraint of =0.01KN/m takes the vertical support counterforce of the lifted structure under the 1.0 time of self-weight load at each lifting hanging point as the synchronous lifting force of each hanging point.
Further, after the constraint is applied to the simulation model, leveling the model with a certain lifting height and correcting the leveled model;
the process of leveling a model at a certain hoisting height comprises the following steps: determining the vertical deformation of each lifting point, and adjusting the vertical position of each lifting point to ensure that the vertical positions of all the lifting points are consistent with the position of the highest lifting point; correcting the vertical rigidity constraint of each lifting point by taking the length of the steel strand of the lifting point with the highest vertical position as the calculated length of all the lifting points;
the process of correcting the leveled model comprises the following steps: if the stress ratio of the large-span steel structure 1.3 times of the dead weight load key component is not more than 0.75, the stress ratio of the common component is not more than 0.85; (2) under the load of 1.0 times of self weight, the bending deflection between adjacent hanging points of the large-span steel structure does not exceed 1/250 of the span of the large-span steel structure; the section of the rod piece is enlarged or a temporary reinforcing member is added to adjust the conditions to meet the conditions, and the model and the synchronous lifting force are updated, wherein the key member is all the rod pieces between two adjacent sections of the lifting point, and the common member is the rod pieces except the key member.
Further, the adjacent suspension point refers to the suspension point directly adjacent to the current suspension point, and does not include the suspension point on the diagonal.
Further, the first threshold is 0.95.
Further, the second threshold is 1/250 of the span between the current suspension point and the corresponding adjacent suspension point.
Further, the third threshold is 1.200.
Further, the fourth threshold is 1.0.
Has the beneficial effects that: according to the asynchronous lifting control method for the large-span steel structure, provided by the invention, different lifting points are respectively analyzed and controlled, and the influence between adjacent lifting points is considered, so that the control on each lifting point is more accurate, the safety in the lifting process is improved, the repeated hovering is avoided, and the construction efficiency is improved.
Drawings
FIG. 1 is a schematic flow chart of an asynchronous lifting control method;
FIG. 2 is a schematic view of a large span steel structure;
fig. 3 is a schematic distribution diagram of the hanging points.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention; the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Examples
The embodiment provides a method for controlling asynchronous lifting of a large-span steel structure, which specifically comprises the following steps:
s1, establishing a fine analysis model of a large-span steel structure in a lifting process;
and S2, respectively determining a control method of each lifting point based on the lifting process fine analysis model.
Specifically, step S1 includes the following steps:
s11, firstly establishing a finite element simulation model of the large-span steel structure, and determining the synchronous lifting force F of each lifting point zi ；
In simulationApplying elastic constraint at the lower lifting point of the model, completely constraining the vertical deformation of the lower lifting point, and simultaneously applying K at the lower lifting point X ＝K Y And (3) horizontal constraint of =0.01KN/m, and taking the vertical support counterforce at each lifting hoisting point under the action of 1.0 time of the self-weight load of the structure as the synchronous lifting force of each hoisting point.
S12, respectively applying lateral constraint and vertical constraint to the finite element simulation model according to the height of the large-span steel structure;
wherein the lateral restraint applied comprises applying K at the drop point X ＝K Y ＝F zi A horizontal constraint of/l, where K X Constraint in the X direction, K Y Constraint in the Y direction, F zi And l is the length of the steel strand from the lower lifting point of the steel strand to the top of the lifting device in the lifting process.
Applying vertical restraint includes applying K at the drop point Z ＝3F Zi E/f ptk l, where E is the modulus of elasticity of the steel strand, E =195000mpa ptk Is the standard value of the tensile strength of the steel strand, f ptk ＝1860MPa。
Because the lengths of the steel strands at different lifting heights are different, the lateral constraint and the vertical constraint of the steel strands on the lifted structure at different lifting heights are also different.
S13, leveling the model;
when the large-span steel structure is just separated from the jig frame, namely 1m off the ground, the vertical deformation of each lifting point is inconsistent, mainly because the vertical rigidity is equal to EA/l, wherein E is the same, the area A of each steel strand is determined by 3 times of synchronous lifting force, so each lifting point EA is proportional, but the lengths of the steel strands of each lifting point are inconsistent, and the lifted structure needs to be leveled. Leveling needs to be carried out at least twice in the actual lifting process, wherein the leveling needs to be carried out for the first time when the lifting platform is 1m away from the ground, and the leveling needs to be carried out for the second time when the lifting platform is close to the designed position.
The leveling process comprises the following steps: determining the vertical deformation of each lifting point, and adjusting the vertical position of each lifting point to ensure that the vertical positions of all the lifting points are consistent with the position of the highest lifting point; and correcting the vertical rigidity constraint of each lifting point by taking the length of the steel strand of the lifting point with the highest vertical position as the calculated length of all the lifting points.
S14, correcting the leveled model;
judging whether the structure simultaneously meets the conditions that (1) the stress ratio of the large-span steel structure at 1.3 times of the dead load key component is not more than 0.75 and the stress ratio of the common component is not more than 0.85; (2) under the load of 1.0 times of self weight, the bending deflection between adjacent hanging points of the large-span steel structure does not exceed 1/250 of the span of the large-span steel structure. If the two conditions are met simultaneously, the model does not need to be adjusted; if the conditions are not met, the cross section of the rod piece is enlarged or a temporary reinforcing member is additionally arranged to be adjusted to meet the conditions at the same time, and the model and the synchronous lifting force are updated, wherein the key members are all the rod pieces between two adjacent sections of the lifting point, and the common members are the rod pieces except the key members.
In the embodiment, synchronous lifting analysis is respectively carried out on structures with different heights, namely 1 meter from the ground, 20 meters from the ground and a design position. Computational analysis shows that different lifting heights have almost no influence on the mechanical property of the lifted structure, the maximum stress ratio of the structural members is 0.528, the maximum deformation of the web members near the lifting point of the same member occurs at the cantilever part at the end part, and the maximum deformation is 1/815 of the cantilever span, so that the requirements are met.
And analyzing a control method for asynchronous lifting of each lifting point at a certain height based on the leveled synchronous lifting models at different heights. Analysis shows that the lifting height is lower, the asynchronous lifting of each lifting point is more sensitive, and the lifting control of each lifting point is stricter, so that the control method of each lifting point of the fine analysis model in the lifting process of the large-span steel structure is analyzed and determined by taking the lifting height just separated from a jig frame, namely 1m away from the ground as an example in the subsequent embodiment.
Specifically, step S2 includes the following steps:
s21, local adjustment is carried out according to adjacent hoisting points;
and S22, carrying out overall adjustment according to all lifting points.
In step S21, the process of determining a control method for a current suspension point includes:
and adjusting the vertical constraint rigidity of the current hoisting point and each adjacent hoisting point, wherein the adjacent hoisting point refers to the hoisting point directly adjacent to the current hoisting point and does not include the hoisting point on the diagonal. For example, referring to fig. 3, assuming that the suspension point No. 11 is the current suspension point, the adjacent suspension points are suspension points No. 7, no. 10, no. 12 and No. 14; assuming that the 20 th suspension point is the current suspension point, the adjacent suspension points are 17 th, 19 th and 21 th suspension points.
Then the following treatments are respectively carried out:
a. if the maximum stress ratio of the member reaches 0.95, the vertical deformation difference between the current lifting point and each adjacent lifting point is not more than 1/250 of the span between the current lifting point and the corresponding adjacent lifting point, and the super-lifting coefficient of the current lifting point is not less than 1.200 at the moment, and the super-lifting coefficient is taken as the initial super-lifting coefficient of the current lifting point to control the lifting of the current lifting point; the super lifting coefficient is the ratio of the asynchronous lifting force to the synchronous lifting force of the current lifting point.
Taking the adjustment of the lifting point No. 11 as an example, by adjusting the vertical constraint stiffness of the lifting points No. 7, no. 10, no. 12 and No. 14 adjacent to the lifting point No. 11, when the stress ratio of the structural rod reaches 0.95, the vertical deformation difference between the lifting points is smaller than 1/250 of the span, at this time, the super-lifting coefficient of the lifting point No. 11 is 1.350, and the preliminary super-lifting coefficient of the lifting point No. 11 is 1.350. Namely, in the actual lifting process, when the ratio of the over-lifting force of the No. 11 lifting point to the synchronous lifting force exceeds 1.350, the suspension device hovers and adjusts. In the process of adjusting the vertical constraint rigidity, the principle that the super-lifting coefficient of the current lifting point is not less than that of the other lifting points needs to be followed. In addition, multiple different adjustment modes may enable the 11 hoisting points to have multiple initial super-extraction coefficients meeting the above conditions, the minimum initial super-extraction coefficient is taken, and the working conditions of the hoisting points after the 11 hoisting points are adjusted to reach the initial super-extraction coefficients are shown in the table 1.
TABLE 1
It should be noted that, in table 1, the over lift and the unloading force coefficients are both the ratio of the asynchronous lifting force to the synchronous lifting force, and for more specific distinction, a ratio greater than 1 is defined as an over lift coefficient, and a ratio less than 1 is defined as an unloading force coefficient.
b. If the maximum stress ratio of the component reaches 0.95, the vertical deformation difference between the current lifting point and each adjacent lifting point does not exceed 1/250 of the span between the current lifting point and each corresponding adjacent lifting point, the super-lifting coefficient is less than 1.200, the rigidity of the current lifting point and each adjacent lifting point is continuously adjusted until the super-lifting coefficient of the current lifting point reaches 1.200, the vertical deformation difference between the current lifting point and each adjacent lifting point is compared to obtain the minimum vertical deformation difference, and the lifting of the current lifting point is controlled by taking 1.200 as a preliminary super-lifting coefficient and taking the minimum vertical deformation difference as a super-lifting deformation limit value.
Taking the adjustment of the hoisting point No. 18 as an example, by adjusting the rigidity of the hoisting points No. 15, no. 17 and No. 21 adjacent to the hoisting point No. 18, when the stress ratio of the structural rod reaches 0.95, the vertical deformation difference between the hoisting points is smaller than 1/250 of the span, but the over-lifting coefficient of the hoisting point No. 18 is only 1.134 at this time, if 1.134 is directly used as the over-lifting coefficient of the hoisting point No. 18, the hoisting point No. 18 is caused to hover easily in the actual hoisting process, and the hoisting efficiency is affected. And at the moment, dual control of displacement and load is adopted, so that the rigidity of the 18 th hoisting point and the adjacent 15 th, 17 th and 21 st hoisting points is readjusted, the super-lifting coefficient of the 18 th hoisting point is 1.200, the vertical deformation differences between the 18 th hoisting point and the 15 th, 17 th and 21 st hoisting points are compared, the minimum vertical deformation difference is 51.2mm, the lifting of the 18 th hoisting point is controlled by using the initial super-lifting coefficient of 1.200 and the super-lifting deformation limit value of 51.2mm, and 50.0mm can be taken as the super-lifting deformation limit value of the 18 th hoisting point for convenience of operation in actual value taking. Namely, in the actual lifting process, when the ratio of the over-lifting force of the 18 th lifting point to the synchronous lifting force exceeds 1.200 or the deformation difference between the 18 th lifting point and the adjacent lifting point exceeds 50.0mm, the hovering adjustment is carried out.
c. If the stress ratio of the member does not exceed 0.95, but the vertical deformation difference between the current lifting point and each adjacent lifting point exceeds 1/250 of the span of the current lifting point and the corresponding adjacent lifting point, and the super-lift coefficient is less than 1.200, the lifting of the current lifting point is controlled by taking the minimum super-lift coefficient in each adjacent lifting point as a preliminary super-lift coefficient and taking 1/250 of the span of the current lifting point and the corresponding adjacent lifting point as the super-lift deformation limit value of the current lifting point. It should be noted that, because the span values between the current hoisting point and different adjacent hoisting points are different, 1/250 of the minimum value between the current hoisting point and each adjacent hoisting point is selected as the transformation limit value of the super-lift.
Taking the number 21 hoisting point as an example, by adjusting the rigidity of the number 21 hoisting point and the adjacent number 18 and 20 hoisting points, when the deformation difference of the adjacent hoisting points does not exceed 1/250 of the span, the stress ratio of the structural rod is always less than 0.95, which indicates that the number 21 hoisting point is controlled by displacement, so that the smaller value of the span between the number 21 hoisting point and the number 18 and 20 hoisting points is compared, 1/250 of the smaller value of the span is taken as an ultra-extraction deformation limit value, and the ultra-extraction coefficient with the smallest weight of the adjacent hoisting points is taken as the primary ultra-extraction coefficient of the number 21, wherein 1/250 of the smaller value of the span is 118.4mm, the actual value can be 100.0mm, the ultra-extraction coefficient of the number 18 hoisting points in the adjacent hoisting points is the smallest, so that the primary ultra-extraction coefficient of the number 21 hoisting point is 1.200. In the actual lifting process, when the ratio of the over-lifting force of the No. 21 lifting point to the synchronous lifting force exceeds 1.200 or the deformation difference between the No. 20 lifting point and the adjacent lifting point exceeds 100.0mm, hovering adjustment is carried out.
The above-described method is used to analyze and process each suspension point in turn, and the control method of each suspension point is obtained in consideration of the influence of the adjacent suspension points, and the results are shown in table 2.
TABLE 2
From the results in table 2, it can be seen that only the 18 th hoisting point adopts load and displacement dual control, the 19 th and 21 st hoisting points adopt displacement control, and the rest hoisting points adopt load control. In table 2, the initial super-lifting coefficient is a result obtained by considering the influence of adjacent lifting points, and the final super-lifting coefficient is a result obtained by considering the whole lifting point.
The asynchronous lifting control method for the large-span steel structure provided by the embodiment analyzes and controls different lifting points respectively, and considers the influence between adjacent lifting points, so that the control on each lifting point is more accurate, the safety in the lifting process is improved, and the repeated hovering is avoided, and the construction efficiency is improved.
Specifically, the overall adjustment is performed in step S22 by determining the preliminary lifting coefficient of each lifting point and then correcting the lifting coefficients of other lifting points by using one lifting point as a reference lifting point.
The process of correcting the super-lifting coefficient of a certain lifting point to be adjusted by taking a lifting point as a reference lifting point comprises the following steps: and enabling the reference lifting point to reach the corresponding preliminary super-lifting coefficient, adjusting the rigidity of the lifting point to be adjusted under the working condition until the rigidity of the lifting point reaches the corresponding preliminary super-lifting coefficient, and judging as follows:
d. if the maximum stress ratio in the member does not exceed 1.0, and the vertical deformation difference between the lifting point to be adjusted and the adjacent lifting point does not exceed 1/250 of the span of the member or exceed the lifting deformation limit value, no correction is carried out; and controlling the lifting of the lifting point by using the preliminary over-lifting coefficient or the over-lifting deformation limit value in the control mode.
e. If the maximum stress ratio in the member exceeds 1.0, or the vertical deformation difference between the lifting point to be adjusted and the adjacent lifting point exceeds 1/250 of the span of the lifting point or the super-lifting deformation limit value of the lifting point, or the reference lifting point exceeds the preliminary super-lifting coefficient, correcting the lifting point to be adjusted; the correction process comprises the following steps:
and adjusting the rigidity of the reference lifting point and the lifting point to be adjusted to enable the reference lifting point to reach the preliminary over-lifting coefficient, and simultaneously enabling the structural stress ratio to be a fourth threshold value or the deformation difference between the lifting point to be adjusted and the adjacent lifting point to just reach a second threshold value, and taking the over-lifting coefficient of the lifting point to be adjusted at the moment as the corrected final over-lifting coefficient.
Referring to table 3, when the lifting coefficient of the lifting point No. 9 is set as the initial lifting coefficient 1.634, the maximum stress ratio of the structural member reaches 1.075 and exceeds 1.0, and thus the stiffness of the lifting point No. 9 and the lifting point No. 6 is readjusted to make the lifting point No. 6 reach the initial lifting coefficient 1.291, the lifting coefficient of the lifting point No. 9 is 1.434, and the lifting coefficient 1.434 is taken as the final lifting coefficient after the lifting point No. 9 is corrected.
TABLE 3
The above-described method is used to analyze and process each suspension point in turn, and the control method of each suspension point is obtained in consideration of the influence of the entire suspension point, and the results are also shown in table 2.
In this embodiment, a refined analysis model that can consider the steel strand pair of different lifting heights to the lifted structure is established, the dynamic influence between each lifting point and all other lifting points is further considered, the dynamic change between each lifting point can be more real, the accuracy and the safety of the control of each lifting point are further improved, and the construction efficiency is improved by hovering.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. It will be apparent to those skilled in the art that various equivalent substitutions and obvious modifications can be made without departing from the spirit of the invention, and all changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
Claims (10)
1. The asynchronous lifting control method for the large-span steel structure is characterized by comprising the following steps of:
establishing a fine analysis model of the lifting process of the large-span steel structure;
the control method for respectively determining each hoisting point based on the refined analysis model of the lifting process comprises the following steps:
adjusting the vertical constraint rigidity of the current hoisting point and each adjacent hoisting point, respectively processing the following steps,
a. if the maximum stress ratio of the member reaches a first threshold value, the vertical deformation difference between the current lifting point and each adjacent lifting point does not exceed a second threshold value, and the super-lifting coefficient of the current lifting point is not smaller than a third threshold value at the moment, and the super-lifting coefficient is taken as the primary super-lifting coefficient of the current lifting point to control the lifting of the current lifting point; the super lifting coefficient is the ratio of the asynchronous lifting force and the synchronous lifting force of the current lifting point;
b. if the maximum stress ratio of the component reaches a first threshold value, the vertical deformation difference between the current lifting point and each adjacent lifting point does not exceed a second threshold value, and the super-lifting coefficient is smaller than a third threshold value, continuously adjusting the rigidity of the current lifting point and each adjacent lifting point until the super-lifting coefficient of the current lifting point reaches the third threshold value, comparing the vertical deformation difference between the current lifting point and each adjacent lifting point to obtain a minimum vertical deformation difference, and controlling the lifting of the current lifting point by taking the third threshold value as a preliminary super-lifting coefficient and the minimum vertical deformation difference as a super-lifting deformation limit value;
c. and if the stress ratio of the member does not exceed the first threshold value, but the vertical deformation difference between the current lifting point and each adjacent lifting point exceeds a second threshold value, taking the minimum super-lifting coefficient in each adjacent lifting point as a preliminary super-lifting coefficient, and taking the second threshold value as a super-lifting deformation limit value of the current lifting point to control the lifting of the current lifting point.
2. The asynchronous lifting control method for the large-span steel structure according to claim 1, wherein the control method for determining each lifting point further comprises the following steps: after determining the initial super-lifting coefficient of each lifting point, correcting the super-lifting coefficients of other lifting points by taking one lifting point as a reference lifting point;
the process of correcting the super-lifting coefficient of a certain lifting point to be adjusted by taking a lifting point as a reference lifting point comprises the following steps: and enabling the reference lifting point to reach the corresponding preliminary super-lifting coefficient, adjusting the rigidity of the lifting point to be adjusted under the working condition until the rigidity reaches the corresponding preliminary super-lifting coefficient, and judging as follows:
d. if the maximum stress ratio in the member does not exceed the fourth threshold value, and the vertical deformation difference between the lifting point to be adjusted and the adjacent lifting point does not exceed the second threshold value or the lifting deformation limit value of the lifting point, no correction is carried out;
e. if the maximum stress ratio in the member exceeds a fourth threshold value, or the vertical deformation difference between the lifting point to be adjusted and the adjacent lifting point exceeds a second threshold value or the lifting point exceeding the lifting deformation limit value, or the reference lifting point exceeds a preliminary lifting coefficient, correcting the lifting point to be adjusted; the correction process comprises the following steps:
and adjusting the rigidity of the reference lifting point and the lifting point to be adjusted to enable the reference lifting point to reach the preliminary over-lifting coefficient, and simultaneously enabling the structural stress ratio to be a fourth threshold value or the deformation difference between the lifting point to be adjusted and the adjacent lifting point to just reach a second threshold value, and taking the over-lifting coefficient of the lifting point to be adjusted at the moment as the corrected final over-lifting coefficient.
3. The asynchronous lifting control method for the large-span steel structure according to claim 1, wherein the establishing of the refined analysis model for the lifting process of the large-span steel structure comprises the following steps:
respectively applying lateral constraint and vertical constraint to the simulation model according to the lifting height;
applying lateral restraint includes applying K at the drop point X ＝K Y ＝F zi A horizontal constraint of/l, where K X Constraint in the X direction, K Y Constraint in the Y direction, F zi The synchronous lifting force of the lifting point under the self-weight load of the lifting structure, and the length of the steel strand from the lower lifting point of the steel strand to the top of the lifting device in the lifting process;
applying vertical restraint includes applying K at the drop point Z ＝3F Zi E/f ptk l, where E is the modulus of elasticity of the steel strand, f ptk Is the standard value of the tensile strength of the steel strand.
4. The asynchronous lifting control method for the large-span steel structure according to claim 3, characterized in that the synchronous lifting force F zi The determination process of (2) includes: applying elastic constraint at the lower lifting point of the simulation model, completely constraining the vertical deformation of the lower lifting point, and simultaneously applying K at the lower lifting point X ＝K Y And the horizontal constraint of =0.01KN/m takes the vertical support counterforce of the lifted structure at each lifting hanging point under the 1.0 time of self-weight load as the synchronous lifting force of each hanging point.
5. The asynchronous lifting control method for the large-span steel structure according to claim 4, characterized in that after the constraint is applied to the simulation model, the method further comprises the steps of leveling the model at a certain lifting height and correcting the leveled model;
the process of leveling a model at a certain hoisting height comprises the following steps: determining the vertical deformation of each lifting point, and adjusting the vertical position of each lifting point to make the vertical positions of all the lifting points consistent with the position of the highest lifting point; correcting the vertical rigidity constraint of each lifting point by taking the length of the steel strand of the lifting point with the highest vertical position as the calculated length of all the lifting points;
the process of correcting the leveled model comprises the following steps: if the stress ratio of the key member of the large-span steel structure which is 1.3 times of the dead weight load is not more than 0.75 and the stress ratio of the common member is not more than 0.85, the stress ratio of the key member of the large-span steel structure is not more than 1; (2) under the load of 1.0 times of self weight, the bending deflection between adjacent hanging points of the large-span steel structure does not exceed 1/250 of the span of the large-span steel structure; the section of the rod piece is enlarged or a temporary reinforcing member is added to adjust the conditions to meet the conditions, and the model and the synchronous lifting force are updated, wherein the key member is all the rod pieces between two adjacent sections of the lifting point, and the common member is the rod pieces except the key member.
6. The asynchronous lifting control method for the large-span steel structure as recited in claim 1, wherein the adjacent suspension point refers to a suspension point directly adjacent to the current suspension point, and does not include a diagonal suspension point.
7. The asynchronous lifting control method for the large-span steel structure according to claim 1, wherein the first threshold is 0.95.
8. The asynchronous lifting control method for the large-span steel structure as recited in claim 1, wherein the second threshold is 1/250 of the span between the current lifting point and the corresponding adjacent lifting point.
9. The asynchronous lifting control method for the large-span steel structure according to claim 1, wherein the third threshold is 1.200.
10. The asynchronous lifting control method for the large-span steel structure according to claim 2, wherein the fourth threshold is 1.0.
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