CN221590125U - Preassembled truss - Google Patents

Abstract

The utility model relates to the technical field of buildings, in particular to a preassembled truss, which comprises the following components: a main rod; the web rib is in a continuously bent wave shape, the web rib is provided with an upper bending point and a lower bending point, and the upper bending point is fixedly connected with the main rod; the fixing piece is fixedly arranged at the lower section of the web bar and is provided with a fixing part extending out of the side of the web bar, so that the longitudinal bar is arranged at the lower section of the web bar, and when the extending direction of the longitudinal bar is approximately the same as that of the main bar, the fixing part can extend to the upper side or the lower side of the longitudinal bar, so that the fixing part can limit the movement of the longitudinal bar.

Description

Preassembled truss

Technical Field

The utility model relates to the technical field of buildings, in particular to a preassembled truss.

Background

The superimposed sheet is wide in application component in the assembled building, and the superimposed sheet generally includes the truss and pours the body, and the lower extreme of truss pours the connection together with the reinforcing bar of pouring in the body, and the truss can increase the superimposed sheet in transportation, the structural strength of pouring, prevents the curved deformation of superimposed sheet.

When the laminated slab is processed, the truss is placed on the die table after the transverse steel bars and the longitudinal steel bars are arranged in a bundling mode to manufacture a steel bar 8 net, and the truss is placed on the connecting net, wherein the truss comprises an upper chord member, a lower chord member and a web member.

The prior art has the following problems that the lower chord member and the longitudinal bars in the reinforcing mesh are fixed on the web members in a welding mode, when the truss is arranged, the lower chord member is easy to overlap with the longitudinal bars, and redundant waste of the lower chord member and the longitudinal bars is caused, so that the consumption of the reinforcing bars is reduced by adopting the lower chord member as a longitudinal bar of a die table. The mode of web member and bottom chord member fixed is inconvenient when the equipment is many, like when processing to prestressing force superimposed sheet, the bottom chord member of former welded fastening can't be used as prestressing force longitudinal reinforcement, one of them avoid this problem is to tie up web member and longitudinal reinforcement and be connected to keep the activity degree of freedom of longitudinal reinforcement when applying prestressing force to longitudinal reinforcement, and when the mode of binding up longitudinal reinforcement and web member on the spot of mould platform is implemented, the construction degree of difficulty is big in the binding up of mould platform top, and influence the cast in situ progress, and in the bundling up process, the relative position of longitudinal member and web member is difficult for adjusting and determining, the crooked problem of longitudinal reinforcement appears easily.

Thus, improvements to existing trusses are highly desirable.

Disclosure of utility model

In order to solve the technical problems, the utility model provides the preassembled truss, which can conveniently assemble the longitudinal rod by optimizing the structure provided with the web bars, and effectively solves the problems in the prior art.

In order to solve the above problems, the present utility model provides a pre-installed truss capable of fixing a side rail, comprising: a main rod; the web rib is in a continuously bent wave shape, the web rib is provided with an upper bending point and a lower bending point, and the upper bending point is fixedly connected with the main rod; the fixing piece is fixedly arranged at the lower section of the web bar and is provided with a fixing part extending out of the side of the web bar, so that the longitudinal bar is arranged at the lower section of the web bar, and when the extending direction of the longitudinal bar is approximately the same as that of the main bar, the fixing part can extend to the upper side or the lower side of the longitudinal bar, so that the fixing part can limit the movement of the longitudinal bar.

Further, the fixing piece is fixedly connected to a part between the upper bending point and the lower bending point of the web, and the fixing piece is provided with a fixing part extending out of the lateral side of the web; the fixing piece is arranged in such a way that the projection distance between the lower edge of the fixing piece and the upper edge of the lower bending point is greater than the radial dimension of the longitudinal rod along the axial direction of the main rod, so that a space for installing a bearing part is arranged between the longitudinal rod and the upper edge of the lower bending point.

Further, the end portion of the fixing portion is bent downwards to form a first side limiting portion, and the first side limiting portion can stop the longitudinal rod on a path that the longitudinal rod moves away from the web bars.

Further, two web ribs are arranged at intervals along the width direction of the main rod bottom, the fixing piece comprises a pressing rib, and the part, extending out of the side of the web ribs, of the pressing rib forms the fixing part; the pressing ribs are connected with two web ribs of the main rod, or the web ribs are respectively provided with the pressing ribs.

Further, the preassembled truss further comprises a bearing rib which is lapped on the upper side of the lower bending point, the bearing rib is provided with a bearing part which extends out of the side of the web rib, and the fixing part and the bearing part can clamp and fix the longitudinal rod.

Further, two web bars are arranged at intervals along the width direction of the main rod bottom, and the bearing bars extend to the lower bending points of the two web bars of the main rod.

Furthermore, the clearance between the fixing part and the bearing part projected in the axial direction of the main rod is smaller than or equal to the radial dimension of the longitudinal rod.

Further, the lower ends of the web members extend transversely to form the fixing members.

Further, the web member lateral extending portion is folded upwards to form the lower bending point, so that when the longitudinal rod is placed on the upper side of the web member lateral extending portion, the portion of the web member vertically extending at the lower bending point can be limited at the side of the longitudinal rod.

Further, the distance between the lower edge of the lower bending point and the upper edge of the transverse extension of the web is greater than the radial dimension of the longitudinal rod, so that a space for installing the pressing component is provided between the longitudinal rod and the lower edge of the upper bending point.

The utility model has the beneficial effects that the structure of the web member is optimized, so that the longitudinal rod can be conveniently assembled, and the problems in the prior art are effectively solved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the utility model and do not constitute a limitation on the utility model. In the drawings:

fig. 1 is a schematic structural view of an assembled side rail according to an embodiment of the present utility model.

Fig. 2 is a schematic side view of the embodiment of fig. 1.

Fig. 3 is a schematic partial structure of another embodiment of the present utility model.

Fig. 4 is a schematic side view of another embodiment of the present utility model.

FIG. 5 is a schematic side cross-sectional view of another embodiment of the present utility model after assembly of the side rail.

Fig. 6 is a schematic view of a partial side cross-sectional structure at the boom of the embodiment of fig. 5.

Fig. 7 is a schematic cross-sectional view of a brace according to another embodiment of the utility model.

Fig. 8 is a schematic view of an assembled side rail according to another embodiment of the present utility model.

Fig. 9 is a schematic side view of the embodiment of fig. 8.

Fig. 10 is a schematic side cross-sectional view of the embodiment of fig. 8 at the boom.

Wherein: 1. a main rod; 2. a web rib; 3. a bending point is upwards bent; 4. a lower bending point; 5. a longitudinal bar; 6. pressing and holding the ribs; 601. a fixing part; 602. a first side limiting part; 7. a supporting rib; 701. a support part; 702. a second side limit part; 8. reinforcing steel bars.

Detailed Description

In order to more clearly illustrate the general inventive concept, reference will be made in the following detailed description, by way of example, to the accompanying drawings.

It should be noted that in the following description, numerous specific details are set forth in order to provide a thorough understanding of the present utility model, but that the present utility model may be practiced otherwise than as described herein, and therefore the scope of the present utility model is not limited by the specific embodiments disclosed below.

In addition, in the description of the present utility model, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the drawings, are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. However, it is noted that a direct connection indicates that two bodies connected together do not form a connection relationship by an excessive structure, but are connected to form a whole by a connection structure. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present utility model, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present utility model. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

In the present utility model, as shown in fig. 1, there is provided a pre-installed truss capable of fixing a side rail 5, comprising: a main lever 1; the web member 2 is in a continuously bent wave shape, the web member 2 is provided with an upper bending point 3 and a lower bending point 4, and the upper bending point 3 is fixedly connected with the main rod 1; and a fixing member fixedly disposed at a lower portion of the web member 2, the fixing member having a fixing portion 601 extending laterally of the web member 2 such that the fixing portion 601 can extend to an upper side or a lower side of the web member 5 when the longitudinal member 5 is disposed at the lower portion of the web member 2 and an extending direction of the longitudinal member 5 is substantially the same as that of the main member 1 (substantially the same as that described herein, in an ideal state, the longitudinal member and the main member should be the same in extending direction, and are affected by unsatisfactory mounting and machining accuracy, and in a practical state, can be only substantially the same, and an angular deviation of the two is generally not more than 15 °), so that the fixing portion 601 can be extended to an upper side or a lower side of the longitudinal member 5 to restrict movement of the longitudinal member 5.

The preassembled truss of the utility model can position the stop vertical rod 5 through the fixing part 601 when the vertical rod 5 is installed and fixed, and is convenient for installing the vertical rod 5 at the lower section of the web member 2. In some working conditions, the longitudinal rods 5, the main rods 1 and the web bars 2 can be assembled in advance at a truss processing site to form truss assemblies, and then the truss assemblies are conveyed to a die table and can be directly used. The vertical rod 5 is fixed in advance by a fixing member, and a limiting method such as strapping or clipping may be adopted, so that when the vertical rod 5 is prestressed, the vertical rod 5 has a deformation space for applying the prestressing force in the longitudinal direction thereof, and the prestressing force of the vertical rod 5 is not affected.

According to the preassembled truss, the main rod 1 and the web bars 2 can be integrally and fixedly connected in advance in a truss processing plant, so that the working efficiency of centralized assembly is higher, and the truss is not limited by a die bench site. The truss is directly placed on the die table for pouring, and the truss is not required to be bound again at a pouring station, so that the problems of high binding construction difficulty and low site binding efficiency caused by binding the truss at the station of the laminated slab processing and pouring are avoided.

In addition, the fixing portion 601 fixed in advance can be used as a reference position of the vertical bar 5 at the time of assembly, and the position of the vertical bar 5 after installation can be ensured to be stable, so that the vertical bar 5 is prevented from being skewed.

And through setting up at least one in mounting and the casting die at web 2, on the one hand can improve the spacing stability to vertical pole 5, on the other hand, at least one in mounting and the casting die is stable in position when the equipment, has reduced the degree of difficulty of fixing and adjustment when the equipment.

The preassembled truss is suitable for pouring short-mould-stage laminated plates, particularly suitable for processing and manufacturing prestressed laminated plates, and aims at working conditions of individual processing of non-standard laminated plates by adopting short-mould-stage. It should be noted that, the use scenario of the pre-assembled truss of the present utility model is not limited to the prestressed laminated slab, and is also applicable to the conventional non-prestressed laminated slab.

For the implementation of the fixing element according to the present utility model, in a preferred embodiment, as shown in fig. 1, 3, 4, 5 and 7, more specifically, the fixing element is fixedly connected to a portion between the upper bending point 3 and the lower bending point 4 of the web 2, and the fixing element has a fixing portion 601 extending laterally of the web 2; the fixing piece is arranged in such a way that the projection distance between the lower edge of the fixing part 601 and the upper edge of the lower bending point 4 is greater than the radial dimension of the vertical rod 5 along the axial direction of the main rod 1, so that a space for installing the bearing part 701 is arranged between the vertical rod 5 and the upper edge of the lower bending point 4.

As shown in fig. 1, 3, 4, 5 and 7, the fixing member may be fixedly connected to the web member 2, and the vertical rod 5 may be mounted on the lower side of the fixing portion 601 during assembly, and the support portion 701 may be lap-jointed and fixed on the upper side of the lower bending point 4.

The fixing position of the fixing piece is optimized, so that a space for arranging the bearing part 701 is provided for the lower side of the vertical rod 5, and a convenient space for operation is provided for a person skilled in the art to implement assembly, and as an example, the vertical rod 5 is fixed between the fixing parts 601 in an up-and-down limiting manner through the bearing part 701, so that the vertical rod 5 is installed.

In an alternative embodiment, the support 701 can be overlapped on the lower bending point 4 and the side rail 5 can be assembled by inserting the side rail 5 between the fixing element and the lower support element.

For the illustrated embodiment, a further optimization is that, as shown in fig. 1 and 3, the end of the fixing portion 601 is bent downward to form a first side limiting portion 602, and the first side limiting portion 602 can stop the longitudinal rod 5 on a path that the longitudinal rod 5 moves away from the web 2.

As shown in fig. 1 and 3, the first side limiting portion 602 is provided, so that the vertical rod 5 can be limited to move laterally and separate from falling after being mounted between the fixing portion 601 and the supporting portion 701.

For the limiting mode of the vertical rod 5, as an alternative to setting the bearing part 701, as shown in fig. 4, the bearing part 701 may be set to be a bearing rib 7, the bearing rib 7 extends out of the side of the web rib 2 to form the bearing part 701, the end of the bearing rib 7 is bent upwards to form a second side limiting part 702, and the second side limiting part 702 can stop the vertical rod 5 on the path that the vertical rod 5 moves away from the web rib 2.

Or the fixing part 601 is provided with a first side limiting part 602 and the bearing part 701 is provided with a second side limiting part 702.

In the embodiment shown in fig. 1, 4, 5 and 7, for the arrangement of the lower support, more specifically, the bottom of the main rod 1 is provided with two web ribs 2 at intervals along the width direction, the fixing member includes a pressing rib 6, and the part of the pressing rib 6 extending out of the lateral side of the web rib 2 forms the fixing portion 601; the pressing rib 6 is connected with the two web ribs 2 of the main rod 1, as shown in the figure, the pressing rib 6 with one section is arranged on the lower side of the single main rod 1, and two ends of the pressing rib 6 are respectively welded and fixed on the two web ribs 2, so that the fixing stability of the pressing rib 6 can be improved, and the structural strength of the truss can be integrally enhanced.

For the arrangement of the holding ribs 6, in an alternative embodiment, as can also be seen in fig. 3, the web ribs 2 are each provided with the holding ribs 6. Therefore, the use amount of the reinforcing steel bars 8 can be reduced by arranging the pressing rib 6 in the process of sectioning at the lower side of the main rod 1, and the web bars 2 at the two sides of the main rod 1 can be deformed more independently, so that when the longitudinal rod 5 applies prestress, the force transmitted by the deformation of the longitudinal rod 5 to the web bars 2 can be transmitted to the deformation space of the longitudinal rod 5 through the deformation of the web bars 2, and the influence of the web bars 2 on the longitudinal rod 5 when the prestress is applied is reduced.

In the embodiments of fig. 1, 3, 4, 5 and 7, the supporting rib 7 is used to assist the description of the installation of the fixing element, and this is not a limitation of the scope of the present utility model as claimed, and the present utility model is not limited to the implementation of the embodiment of the present utility model necessarily including the supporting rib 7 as shown in the drawings, but the present utility model is not limited to the implementation of the embodiment of the present utility model by providing a space for installing the supporting portion 701 under the vertical rod 5.

In the illustrated embodiment, for example, the support part 701 is provided, as shown, the preassembled truss further includes a support rib 7 overlapped on the upper side of the lower bending point 4, the support rib 7 has a support part 701 extending out of the lateral side of the web 2, and the fixing part 601 and the support part 701 can clamp and fix the vertical rod 5.

As shown in the figure, the portion of the supporting rib 7 overlapping the lower bending point 4 is provided as a straight rib, so that the supporting rib 7 can be conveniently processed and assembled.

For the illustrated embodiment, the support part 701 is further specifically provided with two web ribs 2 at intervals along the width direction of the bottom of the main rod 1, and the support rib 7 extends to the lower bending point 4 of the two web ribs 2 of the main rod 1.

As shown in the figure, the two web bars 2 can be overlapped on two sides of the supporting rib 7, so that the supporting rib 7 can be stably overlapped on the web bars 2 on the lower side of the main rod 1.

Alternatively, the supporting part 701 includes supporting ribs 7, and the supporting ribs 7 extend into at least two upper sides of the lower bending points 4 of the web ribs 2 corresponding to the main rod 1. By arranging this in such a way, the brace bars 7 can be cooperatively connected to the main bars 1 extending to the corresponding web bars 2 to assemble a truss assembly having a plurality of main bars 1.

In the illustrated embodiment, the clearance between the fixing portion 601 and the support portion 701 projected in the axial direction of the main lever 1 is smaller than or equal to the radial dimension of the vertical lever 5. As shown in the figure, by arranging in this way, the fixing portion 601 and the supporting portion 701 can elastically clamp the vertical rod 5, so as to fix the vertical rod 5 stably after assembling the vertical rod 5, prevent the vertical rod 5 from falling off, and at this time, the first side limiting portion 602 and the second side limiting portion 702 may not be provided.

The vertical rod 5 is clamped and fixed between the fixing portion 601 and the receiver 701. In a preferred embodiment, when the bearing portion 701 is provided with the second side limiting portion 702 and the fixing portion 601 is provided with the first side limiting portion 602, a projection gap between the upper press and the bearing rib 7 in the axial direction of the main rod 1 may be greater than or equal to a radial dimension of the vertical rod 5, and at this time, the vertical rod 5 has a certain deformation activity space in the vertical direction, and the first side limiting portion 602 and the second side limiting portion 702 can realize clamping and fixing constraint on the vertical rod 5.

In the embodiment of fig. 1 and 4, further specifically, the gap between the first side limiting portion 602 and the web 2 is greater in size than the radial dimension of the longitudinal rod 5, and/or,

The size of the gap between the first side limiting part 602 and the web member 2 is larger than the radial size of the vertical rod 5.

By this arrangement, the vertical bar 5 can have a certain deformation space in the transverse direction between the fixing portion 601 and the supporting portion 701, so that the vertical bar 5 has a relatively flexible adjustment space when the truss is installed, and particularly, when the prestress is applied to the vertical bar 5, the space in which the vertical bar 5 is deformed by the prestress is further ensured.

In the illustrated embodiment, the supporting part 701 is fixed in a manner of overlapping the lower bending points 4 of the two web members 2, which is not limiting to the utility model, and in an alternative embodiment, the supporting part 701 may be fixed at a single nearby lower bending point 4, for example, the supporting part 701 may be clamped at the lower bending point 4 in a clamping manner, and specifically, V-shaped grooves may be provided on the supporting part 701, and the web members 2 are partially embedded in the V-shaped grooves at the lower bending point 4 and at both sides of the lower bending point 4.

Alternatively, in some embodiments, the supporting part 701 may be further configured as a binding rib, where the binding rib directly binds and fixes the vertical rod 5 to the holding rib 6 and the lower bending point 4.

In the illustrated embodiment, further specifically, as shown in the drawing, the fixing member includes a pressing rib 6, the pressing rib 6 is welded to the lower side of the rib of the web 2, and the portion of the pressing rib 6 extending out of the side of the web 2 forms the fixing portion 601. As shown in the figure, the pressing rib 6 is welded to the lower side of the web rib 2, so that when the longitudinal rod 5 transmits upward force to the pressing rib 6, the pressing rib 6 can transmit the force upward to the web rib 2, so as to prevent the tension between the pressing rib 6 and the web rib 2 from being unwelded.

In the illustrated embodiment, as shown in fig. 8, 9 and 10, the lower end of the web member 2 extends laterally to form the fixing member. As shown in the figure, the fixing piece is directly formed by transversely extending the lower end of the web rib 2, so that the working procedures and the cost for processing and assembling the fixing piece are reduced, and the fixing piece can also stably limit the longitudinal rod 5.

Preferably, a further optimization is that the transverse extending part of the web member 2 is folded upwards to form the lower bending point 4, so that when the longitudinal rod 5 is placed on the upper side of the transverse extending part of the web member 2, the part of the web member 2 extending vertically at the lower bending point 4 can be limited at the side of the longitudinal rod 5.

By extending the lower bending point 4 upwards, a lateral limitation of the longitudinal bar 5 can be achieved, which facilitates a limitation fixation during assembly of the longitudinal bar 5.

In the illustrated embodiment, the distance between the lower edge of the lower bending point 4 and the upper edge of the transversely extending portion of the web member 2 is greater than the radial dimension of the longitudinal rod 5, so that there is a space for installing a pressing member between the longitudinal rod 5 and the lower edge of the upper bending point 3.

As shown in the figure, when in installation, the vertical rod 5 is arranged at the bending position at the bottom of the web bar 2, and then the pressing and holding component (the reinforcing steel bar 8 in the figure) transversely passes through the lower bending point 4, and the web bar 2 sequentially presses down the reinforcing steel bar 8, the vertical rod 5 and the transverse extension part of the web bar 2 at the lower bending point 4, so that the assembly and the fixation of the vertical rod 5 and the pressing and holding rib 6 are realized. In this embodiment, the portion of the web member 2 extending upward at the lower bending point 4 forms the second side limiting portion 702 in the embodiment shown in fig. 4, so that a better restraining effect can be achieved on the vertical rod 5, and the vertical rod 5 is prevented from falling off. Moreover, the position of the lower bending point 4 is optimally set, so that the lower bending point can be used as a constraint limit for the steel bar 8 during assembly, multiple purposes are achieved, and convenience is provided for installing the steel bar 8 and the longitudinal bars 5.

When the upward extent of the lower bending point 4 is not sufficient for the provision of the holding-down element, the longitudinal bars 5 can be fastened by means of tie bars to the lateral extent of the web members 2 and the lower bending point 4.

In the subsequent embodiment in which the lower bending point 4 does not extend upwards, the longitudinal bars 5 can be fastened to the web members 2 directly by means of a fastening reinforcement.

In the embodiment where the web member 2 extends transversely, it is preferable that the reinforcement bar 8 is welded to the web member 2, the fixing member and the reinforcement bar 8 can elastically clamp and fix the vertical bar 5, and the vertical bar 5 can be clamped and fixed during installation, or the first side limiting portion 602 is provided on the reinforcement bar 8, at this time, the vertical bar 5 can be threaded between the fixing member and the reinforcement bar 8, or the vertical bar 5 is extruded between the first side limiting portion 602 and the fixing member.

It should be noted that, in the present utility model, the installation position of the holding rib 6 in fig. 1, 3, 4, 5 and 7 is limited by the size of the vertical rod 5, and the upward extending size of the bending down point 4 in fig. 8, 9 and 10 is limited by the vertical rod 5, and it should be understood that this limitation is not a random limitation, and is a constraint limitation based on standards implemented in industry, so that when implemented, a person skilled in the art can obtain a clear limit of the size of the vertical rod 5 based on standard implementation, and thus clearly implement the present utility model.

It should be noted that, in the embodiments shown in fig. 1, 4 and 5, only one longitudinal rod is drawn on each longitudinal rod on one side of the web 2, which is not a limitation of the present utility model, and in alternative embodiments, a plurality of longitudinal rods may be disposed at corresponding positions along the transverse direction.

In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, as relevant to see a section of the description of method embodiments.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.

Claims (10)

1. A pre-assembled truss capable of securing a side rail, comprising:

A main rod;

The web rib is in a continuously bent wave shape, the web rib is provided with an upper bending point and a lower bending point, and the upper bending point is fixedly connected with the main rod;

The fixing piece is fixedly arranged at the lower section of the web bar and is provided with a fixing part extending out of the side of the web bar, so that the longitudinal bar is arranged at the lower section of the web bar, and when the extending direction of the longitudinal bar is approximately the same as that of the main bar, the fixing part can extend to the upper side or the lower side of the longitudinal bar, so that the fixing part can limit the movement of the longitudinal bar.

2. The pre-assembled truss of claim 1, wherein the fastener is fixedly attached to a portion of the web between the upper inflection point and the lower inflection point, the fastener having a fastening portion extending laterally from the web;

The fixing piece is arranged in such a way that the projection distance between the lower edge of the fixing piece and the upper edge of the lower bending point is greater than the radial dimension of the longitudinal rod along the axial direction of the main rod, so that a space for installing a bearing part is arranged between the longitudinal rod and the upper edge of the lower bending point.

3. The pre-assembled truss of claim 2, wherein the ends of the securing sections are bent downwardly to form a first side stop, the first side stop being capable of stopping the longitudinal bar in the path of movement of the longitudinal bar away from the web members.

4. The preassembled truss of claim 2 wherein the main bar bottom is provided with two web bars at intervals along the width direction thereof, the fixing member includes a pressing rib, and a portion of the pressing rib extending out of the side of the web bar forms the fixing portion;

the pressing ribs are connected with two web ribs of the main rod, or the web ribs are respectively provided with the pressing ribs.

5. The pre-assembled truss of claim 2, further comprising a brace bar overlapping the upper side of the lower inflection point, the brace bar having a brace portion extending laterally beyond the web, the securing portion and the brace portion being adapted to clamp the side rail.

6. The pre-assembled truss of claim 5, wherein the bottom of the main bar is provided with two web bars at intervals along the width direction thereof, and the support bars extend to the lower bending points of the two web bars of the main bar.

7. The pre-assembled truss of claim 5, wherein the clearance between the fixing portion and the support portion projected in the axial direction of the main bar is less than or equal to the radial dimension of the longitudinal bar.

8. The pre-assembled truss of claim 1, wherein the web lower ends extend laterally to form the securement members.

9. The pre-assembled truss of claim 8, wherein the web transverse extension is folded upwardly to form the lower inflection point such that the portion of the web extending vertically at the lower inflection point is laterally restrained by the longitudinal rod when the longitudinal rod is positioned above the web transverse extension.

10. The pre-assembled truss of claim 9, wherein the distance between the lower edge of the lower inflection point and the upper edge of the web lateral extension is greater than the radial dimension of the longitudinal members such that there is space between the longitudinal members and the lower edge of the upper inflection point for mounting the compression members.