Method for dismantling inverted triangular truss
Technical Field
The invention relates to the technical field of truss dismantling, in particular to a dismantling method of an inverted triangular truss.
Background
The truss has light dead weight and reasonable stress, and is widely applied to a roof system with a large-span spatial structure. At present, demolition construction of a steel truss is common in municipal bridge engineering, and the existing related truss structure demolition technology mainly comprises three types: erecting a full supporting system; lowering the whole truss to the ground by using a hoist to disassemble and dismantle; energy-gathered cutting blasting demolition technology.
The general erection and removal technology of the full-hall supporting system adopts supporting systems such as a wood structure, a steel pipe scaffold, a prepressing stiff steel structure and the like, all temporary supports are constructed layer by layer from bottom to top, an operation platform is erected at the bottom of the lower chord of the truss, and the truss structure is sequentially removed. The temporary support of the wood structure has lower bearing capacity and is easy to destabilize, a stable anti-side system is difficult to form in the reconstruction of an ultra-long and ultra-high structure, and the application is limited to a certain extent; the steel pipe scaffold supporting system is arranged at a close interval, so that a sufficient operation surface is difficult to provide for subsequent corresponding processes; the stiff steel structure support needs a large operation surface in the mounting and dismounting process, and is not suitable for being used in the dismounting and reconstruction process of the small space structure.
The technology of integrally lowering the truss to the ground by using a lifting machine needs to arrange a lifting device inside the structure or on a temporary frame body, lay lifting hoisting points and integrally lower the truss to the ground and then disassemble and remove the truss. The hoisting machine hoists the whole truss, the clearance area at the same elevation below the truss needs to be ensured, and the requirement on the site is higher; all lifting points are operated synchronously, and dismantling personnel are required to have relatively rich construction experience and professional construction skills.
The cumulative cutting blasting demolition technology determines the position of a blasting notch through careful design, the blasting part adopts a sand bag as a protective material to protect exposed powder charge, and a digital electronic detonator is used for blasting time delay control to implement blasting demolition. Blasting construction is high in danger, blasting safety protection measures are large in investment, shock waves and noise need to be effectively controlled, and protection against accidental metal fragment damage is well achieved.
The large-span inverted triangular truss is long in length and heavy in weight, and the requirement on construction machinery for integral hoisting and dismounting is high; and the single truss with large span height in the hoisting and dismantling process has poor stability and complex hoisting point arrangement, and the dismantling method is not suitable.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defects of high field requirement, complex operation, poor safety and the like in the prior art for truss dismantling, so that the dismantling method of the inverted triangular truss, which has no special requirement on the field, good safety and simple operation, is provided.
In order to solve the technical problem, the invention provides a method for dismantling an inverted triangular truss, which comprises the following steps:
after the purlines and the first beam rod pieces are removed, arranging a supporting jig frame at a preset position of the main truss; then removing the secondary truss and the second secondary beam rod piece connected with the primary truss positioned at the edge; then the main truss is dismantled in sections; and then, sequentially dismantling the remaining main trusses adjacent to the main trusses positioned at the edge until the whole dismantling is finished.
According to the method for dismantling the inverted triangular truss, the preset position of the main truss is a position with the deflection larger than a set value.
The method for dismantling the inverted triangular truss comprises the following specific steps of:
and a first upright column is arranged below the lower chord of the main truss, second upright columns are respectively arranged below the pair of upper chords of the main truss, and the first upright column and the second upright columns are fixed at the top of the supporting jig frame.
The method for dismantling the inverted triangular truss further comprises the step of arranging a circular tube inclined strut on one side of the second upright post.
According to the method for dismantling the inverted triangular truss, the other end of the circular tube inclined strut is arranged close to the first upright post.
The method for dismantling the inverted triangular truss further comprises the step of arranging a distribution beam below the first upright post and the second upright post.
According to the method for dismantling the inverted triangular truss, the distance between every two adjacent distribution beams is 600 mm.
According to the method for dismantling the inverted triangular truss, the inclination angle of the circular tube inclined strut is 45-60 degrees.
The method for removing the inverted triangular truss further comprises the step of arranging end sealing plates at the tops of the first upright post and the second upright post.
According to the method for removing the inverted triangular truss, a pair of ear plates which are arranged oppositely is arranged on the head sealing plate, and a rod piece placing space is formed between the pair of ear plates.
The technical scheme of the invention has the following advantages:
1. according to the method for dismantling the inverted triangular truss, after the purlines and the first beam rod pieces are dismantled, the main truss is dismantled according to the dismantling sequence of the first truss and the second truss, so that the method is convenient to dismantle, high in efficiency and capable of guaranteeing the safety of the structure in the dismantling process. The main truss is dismantled in sections, each section of truss unit is stressed independently and does not influence each other, the transformation of a truss stress system in the dismantling process is clear, and the operation is safe.
2. According to the method for dismantling the inverted triangular truss, the first upright column below the lower chord member, the second upright column below the upper chord member and the circular tube diagonal brace are arranged, so that supporting constraint of the end part of each truss section in the hoisting and dismantling process can be effectively provided, and the integral stability of the truss in the dismantling process is ensured.
3. According to the method for dismantling the inverted triangular truss, the arrangement of the head plates and the pair of ear plates at the tops of the first upright column and the second upright column limits the rotation displacement of the rod piece, and is convenient to dismantle and cut.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a top view of an inverted triangular truss provided by the present invention before removal;
FIG. 2 is a schematic view of FIG. 1 with purlins and first secondary beam members removed;
FIG. 3 is a schematic view of FIG. 2 after the support jig is positioned;
FIG. 4 is the schematic view of FIG. 3 with the primary truss, secondary truss and secondary spar members at the edges removed;
FIG. 5 is a schematic illustration of the removal sequence for the remaining primary trusses after the first primary truss is removed in FIG. 4;
FIG. 6 is a schematic view of the support jig frame positioned below the primary truss;
FIG. 7 is a schematic illustration of FIG. 6 in a disassembled state;
FIG. 8 is an enlarged partial side view of FIG. 6;
fig. 9 is a schematic view of the head plate in use.
Description of reference numerals:
1. a main truss; 2. a secondary truss; 3. a purlin; 4. a first secondary beam member; 5. supporting the jig frame; 6. a first upright post; 7. a second upright post; 8. a head sealing plate; 9. an ear plate; 10. a circular tube diagonal bracing; 11. a distribution beam; 12. the original structure is a column.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. 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 addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
One embodiment of the method for dismantling the inverted-triangular truss shown in fig. 1 to 9 is a long-span inverted-triangular truss formed by connecting a plurality of main trusses 1 arranged in parallel with each other through a sub-truss 2 and a sub-beam member.
The specific dismantling method comprises the following steps:
the purlins 3 and the first secondary beam bar 4 are first removed as shown in fig. 1 and 2. The rest structure of the non-disassembled part ensures reliable longitudinal and transverse connection and can form a stable frame system. The position of a cutting notch during the first beam rod piece dismantling process is required to be at the end part of the first beam rod piece and extend inwards by 50mm away from a node, so that the main truss rod piece is prevented from being damaged by the first beam rod piece dismantling process; the disassembled rod pieces are sorted and stacked orderly according to the section size and the material model; and determining the dismantling sequence and quantity of the first beam and rod pieces, wherein relevant calculation analysis is guaranteed on the basis of theoretical inference.
The supporting jig 5 is arranged at a position where the deflection amount of the main truss is larger than a set value, as shown in fig. 3, the supporting jig 5 is generally arranged at a position where the deflection amount of the main truss is larger. The supporting jig frame enables the stress of each segmented truss unit to meet the requirements of strength and deformation. Specifically, as shown in fig. 8, a first upright 6 is arranged below the lower chord of the main truss, second uprights 7 are arranged below a pair of upper chords of the main truss respectively, the first upright and the second upright are made of wide-flange H-shaped steel, when the truss is heavy, a round pipe can be preferably selected, the first upright and the second upright are distributed in a mode that two sides are high and the middle is low according to the geometric characteristics of the inverted triangular truss, and the top of the first upright and the second upright tightly supports the lower chord and the upper chord to form reliable supporting constraint. The top of first stand with the second stand all sets up head board 8, and the thickness of head board is 16mm, and head board both ends surpass 50 ~ 100mm of truss chord member cross-section maximum dimension. The head plate is welded with a pair of oppositely arranged ear plates 9, and the middle of each ear plate is a placement space of a rod piece so as to form temporary limit. And a circular tube inclined strut 10 is arranged on one side of the second upright column, the other end of the circular tube inclined strut is close to the first upright column, and the inclined angle of the circular tube inclined strut is 45-60 degrees so as to enhance the overall rigidity of the support. The first stand column and the second stand column are fixed to the top of the supporting jig frame. Distribution beams 11 are arranged below the first upright and the second upright, the distribution beams are made of narrow-flange H-shaped steel, the two distribution beams are correspondingly and symmetrically arranged at the central positions of the tops of the supporting jig frames, and the contact positions of the lower flanges of the beams and the tops of the supporting jig frames are reliably connected through fillet welds. The distance between the two distribution beams is 600mm, the segmented cutting position of the truss is positioned between the two distribution beams, and after the truss rod is cut and disconnected, the truss sections at two ends of the cut are supported temporarily to prevent a free cantilever end from being formed.
The secondary girders connected to the primary girders at the edges and the secondary beam bars are then removed as shown in fig. 4.
And then the main truss is dismantled in sections, as shown in figures 6 and 7. The method specifically comprises the following steps: firstly, arranging a supporting jig frame at the subsection point of the inverted triangular truss, changing a single-span simple truss into a two-span continuous truss, and meeting the requirements on the safety of the supporting jig frame and the bearing capacity of a foundation at the bottom of the jig frame. The arranged supporting jig frame ensures the requirements of strength, rigidity and stability of each truss section in the independent stress process after the truss is cut in sections. Then, the large-span inverted triangular truss is cut at the segmentation position. The segmentation position should be 600-800 mm away from the node; before cutting, a cord is fully coated with lime to form a plumbum cutting surface after the cord is closed around a circle on a rod piece; flame grading cutting is adopted on site, namely cutting is carried out along the circumferential direction of the rod piece in a partitioning manner, so that the internal stress of the rod piece at the cutting surface is released slowly, and the deformation of the rod piece caused by sudden release of the stress is prevented; and after the cutting and the segmentation are finished, polishing the cut section in time. And then, disconnecting the connection between the post top support and the truss lower chord, and sequentially hanging the truss section after the splitting section. In the process of hoisting the truss section, 4 hoisting points are arranged at the nodes of the upper chord members. After the truss sections are hung on the ground, the truss sections are placed on the assembling jig frame, and then the members are disassembled, wherein the disassembling sequence is that the web members are firstly disassembled, the upper chord members are assembled, and then the lower chord members are assembled.
The remaining primary girders adjacent to the marginally located primary girders are then removed in sequence, as shown in fig. 5, until the entire removal is complete. And finally, dismantling the original structural column 12 and the supporting jig frame.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.