CN112446099A - Pre-internal force of flexural member and calculation method thereof - Google Patents
Pre-internal force of flexural member and calculation method thereof Download PDFInfo
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Abstract
The invention discloses a pre-internal force of a bent member and a calculation method thereof, which comprises the steps of adjusting the connection state of at least one end of the bent member to be a first connection state and applying preload; adjusting the connection state of at least one end of the flexural member again from the first connection state to the second connection state, unloading the preload and applying a load on the flexural member; and calculating the internal force of the flexural member in the first connection state based on the applied preload, respectively calculating the internal force of the flexural member in the second connection state based on the unloaded preload and the applied load, and superposing the internal forces to obtain the target internal force. By adopting the method, the stress of the homogenized bending member can be homogenized by applying and removing the preload, so that the positive and negative bending moments at the end part and the span of the bending member are effectively reduced and homogenized, the amplitude difference of the bending moment is effectively reduced, the stress performance and the economical efficiency of the bending member in the structure are further improved, and the condition that the misjudgment of the structure is not feasible is avoided.
Description
Technical Field
The invention relates to the technical field of structural engineering, in particular to a pre-internal force of a bent member and a calculation method thereof.
Background
In engineering, in order to analyze the structural strength of a flexural member (such as a beam, a plate or a wall) in actual construction (manufacturing), an analysis calculation is usually performed on the internal force of the flexural member to determine the stress performance of the flexural member in the structure. Currently, for the force calculation of the flexural member, the calculation is usually performed in a manner that the end of the flexural member is set to be fully hinged or fully clamped and bears the full load.
However, it is found in actual design and construction that the distribution of internal forces of the flexural member obtained in the above manner is very uneven, and the existence of such a situation easily causes poor stress performance and economic efficiency of the flexural member in the structure in actual design and construction (or manufacturing), and in severe cases, it may even make misjudgment of the structure impossible.
Disclosure of Invention
The embodiment of the invention discloses a pre-internal force of a bent member and a calculation method thereof, which can effectively homogenize the internal force of the bent member, so that the structural analysis of the bent member can more fully exert the material performance.
The invention provides a pre-internal force of a flexural member and a calculation method thereof, which comprises the following steps
Adjusting a connection state of at least one end of a flexural member to a first connection state, applying a preload on the flexural member;
readjusting the connection state of the at least one end of the flexural member from the first connection state to a second connection state, removing the preload and applying a load on the flexural member;
and calculating the internal force of the flexural member in the first connection state based on the applied preload, calculating the internal force of the flexural member in the second connection state based on the removal of the preload and the applied load, respectively, and superposing the internal forces in the first connection state and the second connection state to obtain a target internal force.
As an alternative implementation manner, in the embodiment of the present invention, the load is a concentrated load and/or a distributed load, and the preload is a load and/or an action with an effect direction consistent with the load effect direction, including any one or a combination of any more of a distributed load, a concentrated load, a hanging load, a pressure force, a tensile force, a tension force, a compression force, a tension force, a support displacement and a temperature action.
As an alternative implementation, in an embodiment of the invention, in the second connection state, the connection stiffness of the at least one end of the flexural member is greater than the connection stiffness of the at least one end of the flexural member in the first connection state.
As an alternative implementation manner, in the embodiment of the present invention, the first connection state is unconnected, hinged or semi-fixed, and the second connection state is hinged, semi-fixed or fixed corresponding to the first connection state.
As an alternative implementation, in the examples of the invention, the load is q, the preload is p, and p < μ q, where μ is a coefficient and μ ≦ 1.
As an alternative implementation, in an embodiment of the present invention, before the adjusting the connection state of at least one end of the flexural member to the first connection state and applying the preload on the flexural member, the method further includes:
adjusting a connection state of at least one end of the flexural member to be the same as or different from the second connection state;
calculating a target load borne by the flexural member in the connection state which is the same as or different from the second connection state;
wherein the target load and the load have the same size and distribution.
As an alternative implementation, in an embodiment of the present invention, the adjusting the connection state of at least one end of the flexural member to the first connection state, and applying a preload to the flexural member includes:
calculating a constraint of the flexural member when in the same or different connection state as the second connection state;
releasing all or part of the restraint of at least one end of the flexural member to adjust the at least one end of the flexural member from the connection state which is the same as or different from the second connection state to the first connection state;
calculating the value of the preload according to the load;
applying the preload on the flexural member.
As an alternative implementation, in an embodiment of the present invention, the adjusting the connection state of the at least one end of the flexural member again to adjust from the first connection state to the second connection state, removing the preload and applying a load on the flexural member includes:
adding a constraint of not less than the released all or part of the constraint at the at least one end of the flexural member to adjust the at least one end of the flexural member from the first connection state to the second connection state;
removing the pre-load applied to the flexural member and applying the load on the flexural member.
As an alternative embodiment, in an embodiment of the invention, the flexural member is a beam, a column, a wall, an arch, a shell or a plate.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
in this embodiment, the total load of the flexural member is calculated, then the preload is applied by adjusting the connection state of at least one end of the flexural member so that it is in the first connection state, and the load to be borne by the flexural member is removed and applied by adjusting the connection state of at least one end of the flexural member from the first connection state to the second connection state. And then respectively calculating the internal force of the bent member based on the two different connection states and superposing all the internal forces to obtain the target internal force. By adopting the method, the flexural member is preloaded and unloaded in stages before the load of the flexural member is applied, and then the load is applied, so that the stress of the flexural member can be homogenized by applying and unloading the preload, the positive and negative bending moments at the end part and the midspan of the flexural member can be effectively reduced and homogenized, the amplitude difference of the bending moment is effectively reduced, the stress performance and the economical efficiency of the flexural member in the structure are improved, and the condition that the misjudged structure is not feasible is avoided.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flow chart of a pre-internal force of a flexural member and a method of calculating the same according to an embodiment of the present invention;
FIG. 2 is a moment diagram of the bending moment of the first embodiment of the present invention with the two ends of the flexural member hinged under preload;
FIG. 3 is a bending moment diagram illustrating the unloading of the fixed supports at the two ends of the flexural member in the first embodiment of the present invention;
FIG. 4 is a bending moment diagram of the load applied by the two ends of the flexural member in the first embodiment of the present invention;
FIG. 5 is a graph of preloaded pre-internal force bending moments of FIGS. 2 and 3 superimposed on the bending moments;
FIG. 6 is a graph of bending moments of FIGS. 5 and 4 superimposed on one another;
FIG. 7 is a bending moment diagram of the two ends of the bending member hinged under the action of the pretension in case two of the present invention;
FIG. 8 is a bending moment diagram of the two ends of the flexural member under the tension action in case two of the present invention;
FIG. 9 is a graph of pre-tensioned pre-internal force bending moments of FIGS. 7 and 8 with superimposed bending moments;
figure 10 is a superimposed moment diagram of figure 4 in figure 9 and case one.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the present invention, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "center", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are used primarily to better describe the invention and its embodiments and are not intended to limit the indicated devices, elements or components to a particular orientation or to be constructed and operated in a particular orientation.
Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meanings of these terms in the present invention can be understood by those skilled in the art as appropriate.
Furthermore, the terms "mounted," "disposed," "provided," "connected," and "connected" are to be construed broadly. For example, it may be a fixed connection, a removable connection, or a unitary construction; can be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements or components. The specific meanings of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific situations.
Furthermore, the terms "first," "second," and the like, are used primarily to distinguish one device, element, or component from another (the specific nature and configuration may be the same or different), and are not used to indicate or imply the relative importance or number of the indicated devices, elements, or components. "plurality" means two or more unless otherwise specified.
The following detailed description is made with reference to the accompanying drawings.
Referring to fig. 1, fig. 1 is a schematic flow chart illustrating a pre-internal force of a bending member and a calculation method thereof according to an embodiment of the present invention. As shown in fig. 1, a method for calculating a pre-internal force of a flexural member may include:
101. adjusting the connection state of at least one end of the flexural member to a first connection state, and applying a preload on the flexural member.
In this embodiment, the bending member mainly refers to a member that bears bending moment, such as a beam, a plate, a wall (e.g., a retaining wall), and the like. Wherein the beams may include single span beams, multi-span continuous beams, floor beams, wall beams, structural beams. The panels may comprise unidirectional panels or bidirectional panels. Such as a roof panel, a basement floor, a basement ceiling, or a wall panel, etc.
Further, the first connected state includes, but is not limited to, any of an unconnected state, a hinged state, or a semi-fixed state.
Specifically, if one end of the flexural member is in an unconnected state, it indicates that the one end of the flexural member is in a cantilever end in a free state at this time, and the other end is a fixed end. If the first connection state of one end of the flexural member is hinged, it indicates that the end of the flexural member is in a rotatable state. If the first connection state of one end of the flexural member is semi-fixed, it indicates that the end of the flexural member is between the two states of rotation and fixation.
In this embodiment, in order to analyze the force applied to the flexural member, at least one end of the flexural member may be adjusted to a conventional connection state having a rigidity greater than that of the first connection state before being adjusted to the first connection state. Specifically, the conventional connection state is a state in which both end rigidities of the flexural member are generated at a time and bear the entire load, the conventional connection state is a state different from the first connection state, and in the conventional connection state, the connection rigidity of at least one end of the flexural member is larger than the connection rigidity of at least one end of the flexural member in the first connection state.
Further, after the two ends of the flexural member are adjusted to the conventional connection state, a target load applied to the flexural member in the conventional connection state may be further calculated, and based on the target load, the load to be applied when at least one end of the flexural member is adjusted to the second connection state in this embodiment is determined. That is, the size and distribution of the target load are the same as the size and distribution of the load.
In the theory of structural engineering, the load may be concentrated load and/or uniform load. The preload in this embodiment is a load and/or various actions whose effect direction is consistent with the load effect direction, and specifically includes any load and action that is consistent with the load direction but is consistent or inconsistent with the load direction, for example, if classified according to the distribution, the preload may include distributed load, concentrated load, stacked load, mounted load, etc., and if classified according to the action method, the preload may be any one or any combination of pressure, tension, counter-pressure, counter-tension, support displacement, and temperature action.
Thus, the step 101 may specifically include the following steps:
1011. the constraints of at least one end of the flexural member in a conventional connected state are calculated.
In this step, at least one end of the flexural member is mainly subjected to constraint calculation when the rigidity is high, and then the flexural member is in a statically indeterminate structural state in a traditional connection state.
1012. And releasing all or part of the restraint of at least one end of the flexural member so as to adjust the at least one end of the flexural member from the conventional connection state to the first connection state.
Taking the example that the number of the constraints of one end of the flexural member in the conventional connection state is 2, when the end is adjusted to be in the first connection state, the two redundant constraints can be completely released, so that the end of the flexural member is in the first connection state with weaker rigidity due to the release of the constraints, and in the first connection state, the flexural member can be in a statically determinate structure state or a statically indeterminate structure state.
Preferably, the constraint may be a bending angle constraint, a displacement constraint, a line constraint, or the like.
1013. And calculating the value of the preload according to the load.
1014. A preload is applied to the flexural member.
In actual construction, taking preload as the preload, the preload can be applied to the flexural member in a manner substantially as follows: when at least one end of the flexural member is in the first connection state, a weight component is added on the flexural member, so that the flexural member is subjected to the downward pressing force.
102. Adjusting the connection state of at least one end of the flexural member again from the first connection state to the second connection state, removing the preload and applying a load on the flexural member.
The step 102 specifically includes the following steps:
1021. adding the number of the restraint which is not less than the released restraint at least one end of the bent member so as to adjust the at least one end of the bent member from the first connection state to the second connection state.
In this embodiment, the second connection state is the same as or different from the conventional connection state, and the second connection state is different from the first connection state. That is, in the second connection state, the connection rigidity of the at least one end of the flexural member is greater than that in the first connection state and is greater than or equal to that in the conventional connection state. The number of connection constraints of the at least one end in the second connection state is greater than or equal to the number of connection constraints of the at least one end in the conventional connection state. The second connection state and the conventional connection state are taken as the same connection state as an example in the invention. The first connection state may then be unconnected, hinged or semi-fixed, and the second connection state may thus be hinged, semi-fixed or fixed. When the first connection state is the unconnected state, the second connection state can be hinged, semi-fixed or fixed; when the first connection state is hinged, the second connection state can be semi-fixed or fixed; and when the first connection state is semi-solid, the second connection state can be solid.
It can be known that, when the first connection state of at least one end of the flexural member is clamped, the second connection state of the end is also clamped; the first connection state at the other end may be a hinged or semi-fixed branch and the second connection state at the other end may be a semi-fixed or fixed branch. That is, the first connection state and the second connection state of at least one end of the flexural member are always different, so that the preload application and removal of the flexural member in different connection states according to the present invention can be achieved.
1022. And calculating the load borne by the bent member and taking a value according to the traditional connection state.
As can be seen from the above, the load and the target load have the same size and distribution.
1023. Removing the pre-load applied to the flexural member and applying a load to the flexural member based on the calculated load.
It should be noted that since the removal of the preload is performed after at least one end of the flexural member has been adjusted from the first connection state to the second connection state. Thus, the order of removing the preload and applying the load may be unlimited for the flexural members as long as they are in the second connection state. For example, the preload may be removed prior to application of the load, the load may be applied prior to removal of the preload, or both removal of the preload and application of the load may be performed simultaneously.
In this embodiment, since the preload is applied to the flexural member when the at least one end of the flexural member is in the first connection state, and the preload is removed when the at least one end of the flexural member is adjusted from the first connection state to the second connection state, it is equivalent to applying a force equal to the preload but opposite to the preload to the flexural member in the second connection state. Taking the preload as the pretension, in this way, the process of applying the pretension load and the process of removing the pretension are equivalent to "pretension" and "release", and from pretension to release, the pretension load is completely zero in the process, but because the two stages are different in state (the first connection state is different from the second connection state), the bending member superposes and stores a certain amount of bending moment, namely, although the pretension load is zero, the bending moment is not eliminated and returns to zero.
It can be appreciated that in the present invention, the connection state of at least one end of the flexural member is generated in stages to form two different connection states, and then the preload is applied in the first connection state to generate an internal force that can generate a smaller preload internal force at a large magnitude of the conventional internal force and a larger preload internal force at a small magnitude of the conventional internal force. The removal of the preload applied in the first connection state in the second connection state corresponds to the application of a load of equal magnitude and opposite direction to the preload, which necessarily generates an internal force in a direction exactly opposite to the conventional internal force, which allows the conventional internal force to be cancelled. Therefore, the internal force generated by applying the preload in the first connection state and the internal force generated by removing the preload in the second connection state are superposed, the preload removal returns to zero, but the internal force cannot be completely offset due to different states and different size distribution of the internal force, and the residual internal force after partially offsetting in the superposition is pre-established before the load application of the traditional flexural member, so the superposition is called as the pre-internal force.
In this embodiment, the load is q and the preload is p, and since the removal of the preload p is equivalent to the application of a load p' having the same magnitude and the opposite direction to the preload p on the flexural member, the load and the preload satisfy the following relationship:
p+p’+q＝q； (1)
p’＝-p； (2)
that is, p < μ q, where μ is a coefficient and μ ≦ 1.
That is to say, by adopting the scheme of the invention, the preload value can be determined by analyzing the relation between the load and the preload, and then the internal force applied to the bent component can be determined.
103. And calculating the internal force of the flexural member in the first connection state based on the applied preload, calculating the internal force of the flexural member in the second connection state based on the unloaded preload and the applied load respectively, and superposing the internal forces in the first connection state and the second connection state to obtain the target internal force.
Specifically, the basic theory of construction suggests that the distribution of forces within a structure or component is related to the distribution of structural stiffness. The node and the component with high rigidity have large internal force distribution. The node and the member with low rigidity have small internal force distribution. Therefore, the node (or support) with larger internal force in the traditional structure or member is connected in stages, so that the rigidity of the first stage (namely the first connection state) is weakened relative to the rigidity of the second stage (namely the second connection state), namely relative to the traditional rigidity (generally the traditional rigidity can be the second connection state, namely the fixed support), namely, the state of the flexural member in the first stage is called as state 1, and the preloading is carried out in the state 1, and the larger node internal force generated by the flexural member is transferred to the smaller node internal force in the flexural member, so that the internal force is transferred and redistributed. That is, the preload applied at State 1 may produce an internal preload force (e.g., a bending moment). In the second stage, the state of the flexural member is adjusted to the same state as the conventional rigidity, which is referred to as state 2. In state 2, removing the preload, which is equivalent to applying a load equal to and opposite to the preload, is referred to as reverse preload, and the reverse preload will generate an internal bending moment in a direction completely opposite to that of the conventional internal bending moment, so that the conventional internal bending moment of the bent member can be reduced. The state 1 preload is superimposed with the state 2 unload, and the preload unload is zeroed, i.e., the reverse preload cancels out the preload to zero. Based on different states, although the preload and the unload generate the internal force bending moment in opposite directions, the magnitude distribution is completely different, so that the magnitude distribution cannot be completely counteracted. The residual internal force bending moment after partial cancellation in the superposition is pre-established before the load application of the bent member, and is called pre-internal force bending moment.
Therefore, the invention mainly adopts the mode of generating the state of at least one end of the flexural member by stages and applying the pre-internal force measure according to the corresponding stage. Wherein, the measure of internal force is as follows: this is achieved by applying the preload in state 1 and unloading in state 2, taking advantage of the different behavior of the two phase connections.
The result of the pre-internal force measures is a subtractive homogenization of the conventional internal forces. The degree of damping-homogenization depends on the relative proportions of the different stiffnesses in the two phases and on the control of the magnitude of the preload, i.e. the preload is controlled to be a proportion of the load, i.e. the ratio of preload to load
The calculation process of the internal force (bending moment as an example) of the flexural member of the present invention will be described in detail below with reference to examples and drawings:
case one
Referring to fig. 2 to 4, the bending member is a single-span beam, the span of the beam is L, the first connection state is hinge support, the second connection state is fixed support, the applied preload is a load consistent with the load distribution and direction, the borne load is a load with uniform full span, and the borne internal force is a bending moment.
Wherein figure 2 shows a bending moment diagram of the flexural member in a hinged condition subject to a preload. Firstly, adjusting the connection state of two ends of a bent member to be in a hinged state, applying preload p on the bent member, wherein the preload p is in a vertically downward direction, and at the moment, the two ends of the bent member support bending moment MAp＝M Bp0, a maximum positive bending moment is generated in the span, and the bending moment generated in the span of the bending member is MCp＝pl2/8。
As shown in fig. 3, fig. 3 shows a bending moment diagram of the flexural member with preload removed in the clamped state. The unloading operation is performed by adjusting both ends of the bent member from the hinge to the fixed support and removing the previously applied preload p. This operation corresponds to the application of a reverse preload p ' equal to the preload and opposite in direction, i.e. p ' ═ -p, in the second connection state, as compared with the first connection state, and a positive bending moment of relatively large amplitude, i.e. M, is generated across the bent member under the action of the reverse preload p 'Ap’＝MBp’＝-p’l2/12＝pl212, generating a negative bending moment M with a relatively small amplitude in the spanCp’＝p’l2/24＝-pl2/24。
Further, as shown in FIG. 4, after the preload p is removed, the load q is applied to the flexural member, which produces an extreme negative bending moment M at both ends of the flexural memberAa＝MBa＝-ql 212, generating a small positive bending moment M in the midspanCa＝ql2/24。
Referring to fig. 5 and 6, fig. 5 is a graph showing the bending moment resulting from the superposition of the bending moment applied to the pre-load of the flexural member and the bending moment applied to the flexural member to remove the pre-load. FIG. 6 is a graphical representation of the bending moments after the pre-load, unload and load bending moments have been superimposed.
That is, the bending moments at the two ends in the two connection states are respectively superposed to obtain a first bending moment amplitude value at the two ends of the bent member as follows:
in a similar way, the bending moments in the midspan of the two connected components are respectively superposed to obtain a second target bending moment amplitude value in the midspan of the bent component:
subtracting the absolute value of the formula (3) and the formula (4) to obtain an absolute value to obtain the bending moment amplitude difference delta of the bent member, namely, the bending moment amplitude difference between the two ends of the bent member and the span
Because p is less than mu q and mu is less than or equal to 1, the amplitude of the bending moment is different
This shows that, under the action of the vertical load uniformly distributed over the full span of the flexural member, the bending moment amplitude difference obtained by adopting the scheme of the embodiment of the invention is as follows
The result of this difference in bending moment amplitude is small and tends to be uniform. Therefore, the method can effectively reduce the difference of the bending moment amplitudes between the two ends of the bent member and the span, thereby being beneficial to improving the stress performance of the bent member in the structure and further being beneficial to improving the safety of the bent member in the structure.
Case two
Referring to fig. 7 to 10, the bending member is a single span beam, the span of the beam is L, the first connection state is hinge support, the second connection state is fixed support, the applied preload is pretension in accordance with the loaded direction, and the loaded load is full span uniform load.
In the hinged condition, as shown in FIG. 7, it is applied firstProper downward pretension load P and two-end support bending moment MAP＝M AP0, a large positive bending moment M is generated in the midspanCP＝Pl/4。
As shown in fig. 8, both ends of the bent member are adjusted to be in a clamped state, and the pre-tension load P applied in the previous state is removed, which is called relaxation. Compared with the previous state, the method is equivalent to applying reverse pretension P' with equal magnitude and opposite direction. Under the action of reverse pretension P', positive bending moment M with relatively large amplitude is generated at two ends of the bent memberAP’＝MBP’Pl/8, a relatively small magnitude negative bending moment M is generated across the spanCP’＝-Pl/8。
As shown in fig. 4, in the second stage clamped state, the load q is applied, and the second stage is actually the two-end clamped load of the conventional flexural member, i.e. the two-end bending moment M of the flexural memberAa＝MBa＝-ql 212; midspan bending moment M of flexural memberCa＝ql2/24。
As shown in fig. 9, fig. 9 is a view showing the superimposed action of bending moments of the flexural member under the action of applying a pre-tension load and removing the pre-tension load, and fig. 10 is a view showing the superimposed action of bending moments under the action of applying a pre-tension load, removing the pre-tension load and applying the load.
And superposing the preloading bending moment (the bending moment for applying the preloading action), the unloading bending moment (the bending moment for removing the preloading action) and the loading bending moment (the bending moment for applying the loading action) by utilizing a superposition principle of a structural theory to obtain the target bending moment.
The target bending moment is respectively a bending moment at two ends and a mid-span bending moment, wherein,
bending moment of supports at two ends of the bent member:
midspan bending moment of the flexural member:
subtracting the absolute value of the bending moment of the two-end support from the absolute value of the midspan bending momentThen, the absolute value is taken to obtain the bending moment amplitude difference delta of the bent member, namely the bending moment amplitude difference between the supports at the two ends of the bent member and the span
This shows that the bending moment amplitude difference of the bending member obtained by the scheme of the embodiment of the invention under the action of the vertical load uniformly distributed in the full span
And is reduced, tending to homogenize.
It is understood that when the first connection state and the second connection state are other states, for example, the first connection state is a hinged support and the second connection state is a semi-fixed support, or the first connection state is a semi-fixed support, the second connection state is a fixed support, etc., and the preload applied in the first connection state is a pretension load, etc., the same as the analysis process in the first case and the second case, which will not be explained in detail herein.
Furthermore, the bending moment reduction and homogenization method provided by the embodiment of the invention is not only suitable for single-span beams, but also suitable for flexural members such as multi-span beams, wall beams, structural beams, plates or retaining walls.
It will be appreciated that the pre-internal force of the flexural member and its method of calculation of the present invention may be used as long as the boundary pedestal stiffness is generated in stages.
In addition, by adopting the scheme of the invention, the preloading and the unloading preloading are respectively carried out when the bent member is in two different connection states, so that the bending moment reduction and homogenization of the bent member can be facilitated, the bending moment amplitude difference of the bent member is reduced, and the stress performance of the bent member in the structure is improved.
It should be understood that the method for calculating the pre-internal force of the flexural member and the flexural member according to the present invention are applicable not only to new construction, but also to existing reconstruction engineering. Specifically, when the method is applied to a new construction, the load and the preload of the flexural member can be obtained through simulation, analysis and calculation, and then the preload and the load are applied in stages according to the actual installation condition of the flexural member.
According to the pre-internal force of the bent member and the calculation method thereof provided by the embodiment of the invention, before the load of the bent member is applied, the pre-load application and the removal are performed on the bent member in a state of stages and stages, and then the load is applied, so that the stress of the bent member can be homogenized by using the pre-load application and removal, the positive and negative bending moments at the end part and the midspan of the bent member are effectively reduced and homogenized, the bending moment amplitude difference is effectively reduced, the stress performance and the economy of the bent member in the structure are further improved, and the condition that the structure is not feasible is avoided being misjudged.
The detailed description is given above to the pre-internal force of a flexural member and the calculation method thereof disclosed in the embodiments of the present invention, and the principle and the implementation of the present invention are explained in this document by applying specific examples, and the description of the above embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (9)
1. A method for calculating the pre-internal force of a flexural member, comprising:
adjusting a connection state of at least one end of a flexural member to a first connection state, applying a preload on the flexural member;
readjusting the connection state of the at least one end of the flexural member from the first connection state to a second connection state, removing the preload and applying a load on the flexural member;
and calculating the internal force of the flexural member in the first connection state based on the applied preload, calculating the internal force of the flexural member in the second connection state based on the removal of the preload and the applied load, respectively, and superposing the internal forces in the first connection state and the second connection state to obtain a target internal force.
2. The method of claim 1, wherein the load is a concentrated load and/or a distributed load, and the preload is a load and/or an effect having an effect direction coinciding with the load effect direction, and comprises any one or a combination of any more of a distributed load, a concentrated load, a hanging load, a pressure force, a tension force, a counter pressure, a counter tension, a support displacement and a temperature effect.
3. The method according to claim 2, wherein in the second connection state, the connection stiffness of the at least one end of the flexural member is greater than the connection stiffness of the at least one end of the flexural member in the first connection state.
4. The method of claim 3, wherein the first connection state is unconnected, hinged, or semi-fixed, and the second connection state is hinged, semi-fixed, or fixed.
5. The method according to any one of claims 1 to 4, wherein the load is q, the preload is p, and p < μ q, where μ is a coefficient and μ ≦ 1.
6. The method of claim 5, wherein prior to the adjusting the connection state of the at least one end of the flexural member to the first connection state, the method further comprises:
adjusting a connection state of at least one end of the flexural member to be the same as or different from the second connection state;
calculating a target load borne by the flexural member in the connection state which is the same as or different from the second connection state;
wherein the target load and the load have the same size and distribution.
7. The method of claim 6, wherein the adjusting the connection state of the at least one end of the flexural member to a first connection state applies a preload on the flexural member comprising:
calculating a constraint of the at least one end of the flexural member at the same or different connection state as the second connection state;
releasing all or part of the restraint of at least one end of the flexural member to adjust the at least one end of the flexural member from the connection state which is the same as or different from the second connection state to the first connection state;
calculating the value of the preload according to the load;
applying the preload on the flexural member.
8. The method of claim 7, wherein said readjusting the connection state of the at least one end of the flexural member from the first connection state to a second connection state, removing the preload and applying a load on the flexural member comprises:
adding a number of the constraints not less than the released number to the at least one end of the flexural member to adjust the at least one end of the flexural member from the first connection state to the second connection state;
removing the pre-load applied to the flexural member and applying the load on the flexural member.
9. A method according to any one of claims 1 to 4, wherein the flexural member is a beam, wall or panel.
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| KR20050026470A (en) * | 2005-02-25 | 2005-03-15 | 안철승 | Method of manufacturing and construction melthod of preflex composite beem by division mode |
| CN105760691A (en) * | 2016-03-04 | 2016-07-13 | 西北农林科技大学 | Method for calculating internal force and deformation of member or structure under action of multiple complex loads |
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| KR20050026470A (en) * | 2005-02-25 | 2005-03-15 | 안철승 | Method of manufacturing and construction melthod of preflex composite beem by division mode |
| CN105760691A (en) * | 2016-03-04 | 2016-07-13 | 西北农林科技大学 | Method for calculating internal force and deformation of member or structure under action of multiple complex loads |
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