Node structure for combining temporary beams and structural beams at the opening of reverse-construction structures

Abstract

The present invention belongs to a node structure for combining a temporary beam and a structural beam at the opening position of a reverse-construction deep foundation pit project. The technical solution is as follows: under normal use conditions, an opening is provided in the column span; under reverse-construction conditions, the temporary beam in the opening is combined with the structural beam outside the opening to form a reverse-construction structural beam that runs the entire length of the column span; the main reinforcement configuration of the reverse-construction structural beam meets the envelope reinforcement requirements of the reverse-construction and normal use stages, and the main reinforcement of the structural beam includes the first main reinforcement of the structural beam in the normal use stage and the second main reinforcement of the structural beam used for reverse-construction reinforcement; the first main reinforcement of the structural beam is anchored into the side wall of the opening according to the support conditions of the normal use stage, and is welded and extended with the temporary main reinforcement of the beam; the second main reinforcement of the structural beam is combined with the remaining temporary main reinforcement of the beam that has not been welded and extended in the temporary beam. This node structure meets the reinforcement and anchoring requirements of both the reverse-construction stage and the normal use stage.

Description

Technical Field

[0001] The invention belongs to a reverse construction method deep foundation pit project, and in particular relates to a structure combining a temporary beam and a structural beam. Background Art

[0002] The reverse excavation method for deep foundation pit engineering differs from the conventional forward excavation method in that it directly utilizes the reverse structural beams and slabs of each underground layer and the “one column and one pile” system as horizontal and vertical supports during the foundation pit implementation phase. However, the vertical structural walls and secondary structures inside the basement are limited by the reverse excavation process and cannot be formed all at once during the reverse excavation phase. They need to be completed layer by layer from bottom to top after the reverse excavation reaches the base and the foundation slab is constructed, so that a complete structural force system that matches the normal use phase can be formed. Therefore, during the reverse excavation phase, structural openings such as ramps, stairs, air shafts, or lifting holes often occur. Because the side walls around the openings cannot be formed all at once, the beam and slab system supported by the side walls becomes cantilevered, changing the original force pattern of the structural system. Since the design and support and anchoring conditions of the main structural system are usually considered according to the normal use phase and do not include the reverse excavation phase working conditions, the design is inconsistent with the actual project. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a node structure for combining temporary beams and structural beams at the opening position of the reverse construction structure. The node structure meets the reinforcement and anchoring requirements of both the reverse construction stage and the normal use stage.

[0004] The technical solution of the present invention is: a node structure for combining a temporary beam and a structural beam at an opening position of a reverse-construction structure, wherein an opening is provided in the column span under normal use conditions; under reverse-construction conditions, the temporary beam in the opening is combined with the structural beam outside the opening to form a reverse-construction structural beam that is continuous in the column span; the intersection of the temporary beam and the structural beam is the position of the opening side wall under normal use conditions, and the main reinforcement configuration of the reverse-construction structural beam meets the envelope reinforcement requirements of the reverse-construction and normal use stages, and the main reinforcement of the reverse-construction structural beam includes the temporary beam main reinforcement of the temporary beam and the structural beam main reinforcement of the structural beam; the structural beam main reinforcement includes the first structural beam main reinforcement in the normal use stage and the second structural beam main reinforcement for reverse-construction reinforcement; the first structural beam main reinforcement is anchored in the opening side wall according to the support conditions in the normal use stage, and is welded and extended with the temporary beam main reinforcement; the second structural beam main reinforcement is merged with the remaining temporary beam main reinforcement in the temporary beam that has not been welded and extended, and is replaced with a continuous steel bar.

[0005] Based on the above technical features: the width of the reverse-construction structural beam is greater than the beam width calculated under normal use conditions.

[0006] Based on the above technical features: the main reinforcement at the corner of the widened part of the beam is anchored into the side wall of the opening, and is welded to the temporary beam main reinforcement.

[0007] This technology is primarily used to address the joint construction issues associated with the combination of temporary beams and structural beams at the openings of reverse-construction structures. On the one hand, by strengthening the cross-section and reinforcement of the structural beams under normal use conditions, and extending them across the opening, a reverse-construction structural beam is formed that extends throughout the entire column span, resolving the cantilever problem of structural members surrounding the opening during the reverse-construction phase. On the other hand, by employing structural measures such as welding and splicing the main reinforcement, the combined beams are designed to envelop according to two-stage working conditions. This ensures that after the temporary reverse-construction beams within the opening are removed, the remaining original structural beams can still meet the reinforcement and anchorage requirements of the normal use phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a plan diagram of the structural system under normal use conditions at the opening location.

[0009] Figure 2 This is a plan diagram of the reverse construction structural system at the opening location.

[0010] Figure 3 It is a planar node structure that combines the temporary beam and the structural beam at the opening of the reverse-construction structure when the reverse-construction structure beam is not widened.

[0011] Figure 4 When widening the top-down structural beam, the plane node structure is formed by combining the temporary beam at the top-down structural opening with the structural beam.

[0012] Figure 5 This is the elevation drawing of the node where the temporary beam at the top-down structural opening is combined with the structural beam; Figure 3 and Figure 4 AA cross-section diagram.

[0013] Reference numerals

[0014] 1-opening side wall; 2-structural beam; 3-temporary beam; 4-structural beam main reinforcement; 5-welded joint; 6-temporary beam main reinforcement; 7-frame column outside the opening; 8-reverse structural beam; 9-corner main reinforcement; 10-beam widening part; 11-through-length reinforcement. DETAILED DESCRIPTION

[0015] The following is a further detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, and are not intended to limit the present invention.

[0016] In the description of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," and "outside" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0017] like Figure 1 As shown, in the original structural system, the structural beam 2 outside the opening is supported by the opening side wall 1 and does not penetrate the opening. The original structural system here specifically refers to the structural state before the reverse construction and reinforcement design, that is, the structural state designed under normal use conditions of the main structure. Because the reverse construction structure needs to consider the load requirements of both the reverse construction stage of the foundation pit and the normal use stage after the foundation pit is completed, and the structural components must be strengthened based on the normal use structural system, the original structural system is the normal structural design state before the reverse construction and reinforcement.

[0018] like Figure 2 As shown, during the reverse construction stage, since the side wall 1 of the opening is vertically reserved and cannot form an effective support function, in order to solve the problem of vertical support of the structure, the structural beam 2 outside the opening is extended toward the opening until the frame column 7 outside the opening, thereby forming a reverse construction structural beam 8 that combines the structural beam 2 outside the opening within the column span and the temporary beam 3 inside the opening, realizing the support conversion of the reverse construction structural system.

[0019] The cross section and reinforcement of the combined reverse construction structural beam 8 are reviewed and strengthened, and the reinforcement design is carried out according to the two-stage envelope reinforcement design of reverse construction and normal use. The reverse construction method uses the main structure beams and slabs as horizontal support members in the foundation pit implementation stage. Therefore, the structural beam and slab system in the reverse construction method not only meets the normal stress requirements of the structure in the normal use stage, but also needs to meet the stress requirements of the structural beams and slabs as the horizontal support system in the foundation pit reverse construction implementation stage. Therefore, the beam and slab system should be enveloped according to the stress conditions of the different working conditions in the two stages. Envelope design refers to the cross-sectional size, bearing capacity and reinforcement of the structural member taking the maximum value that meets the requirements of both the reverse construction stage and the normal use stage. When the reverse construction design requires widening, heightening or strengthening the cross section of the original structural member, on the premise of ensuring that the reinforcement within the cross-sectional range of the original structural member is not lower than the original structural design requirements, main bars and stirrups are added in the widening and heightening range to form a "double" reinforcement system to simultaneously meet the stress reinforcement requirements of the reverse construction stage, thereby realizing the envelope reinforcement design under the two-stage situation.

[0020] like Figure 3 、 Figure 5 As shown, the main reinforcement of the reverse-constructed structural beam 8 includes the temporary beam main reinforcement 6 of the temporary beam 3 and the structural beam main reinforcement 4 of the structural beam 2. The structural beam main reinforcement 4 and the temporary beam main reinforcement 6 are actually the main reinforcement in different sections of the reverse-constructed structural beam 8; the specifications and quantity of the main reinforcement in the two sections are generally unified. According to the requirements of the reverse-construction reinforcement design, a unified steel bar specification is adopted. If the steel bar specification of the structural beam main reinforcement 4 calculated during the normal use phase is different from the steel bar specification calculated during the reverse-construction phase, it can be replaced with the same type and quantity of main reinforcement as the reverse-constructed structural beam 8 during the reverse-construction design based on the steel bar cross-section and other strengths.

[0021] The main reinforcement bars 4 of the structural beams include the first main reinforcement bars for normal use and the second main reinforcement bars for reverse reinforcement. When there is no need to widen the structural beam 2 outside the opening, the main reinforcement bars 4 of the structural beam 2 required by the original structural design, i.e., the first main reinforcement bars, are anchored into the side walls 1 of the opening according to the support conditions during normal use. The temporary main reinforcement bars 6 are connected to the main reinforcement bars 4 by welding. Figure 3 The welded joints 5 shown are staggered according to construction requirements. Welding extensions are welded connections between the temporary beam main reinforcement 6 of the temporary beam within the opening and the main reinforcement 4 of the structural beam outside the opening. The main reinforcement of the first structural beam outside the opening needs to be anchored into the side walls of the opening according to the structural design requirements for normal use. Since it cannot penetrate the entire opening, it must be welded and extended to meet the main reinforcement penetration requirements during the reverse construction phase and to ensure that the external structural beam can still meet the anchoring requirements during normal use after the temporary beam within the opening is removed.

[0022] like Figure 4 、 Figure 5 As shown, when the structural beam 2 outside the opening needs to be widened, that is, when the width of the reverse-constructed structural beam 8 exceeds the structural width of the structural beam 2 under normal use conditions, the first structural beam main reinforcement required by the original structural design for the cross-sectional area of the structural beam 2 and the corner main reinforcement 9 of the widened portion of the beam are anchored into the side wall 1 of the opening according to the support conditions during normal use. Since the widened portion 10 of the beam will be retained during normal use, considering the structural connection between the beam and the wall, the corner main reinforcement 9 should be anchored into the side wall 1 of the opening according to the support conditions during normal use. The temporary beam main reinforcement 6 in the opening and the corner main reinforcement 9 of the widened portion are connected by welding.

[0023] The main reinforcement of the structural beam 4 includes the first main reinforcement of the structural beam in the normal use stage and the second main reinforcement of the structural beam used for reverse reinforcement. The second main reinforcement of the structural beam is combined with the remaining main reinforcement of the temporary beam main reinforcement 6 that has not been welded and extended, and replaced with the continuous steel bar 11. Figure 3 、 Figure 4The middle-length steel bars 11 are shown in dotted lines to distinguish them from the welded main bars. That is, in addition to the above-mentioned welded main bars, the remaining main bars of the second structural beam set for reverse reinforcement can be stretched throughout the reverse structural beam 8.

[0024] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A node structure for combining a temporary beam with a structural beam at an opening in a reverse-construction structure, wherein an opening is provided within the column span under normal use conditions; characterized in that: Under reverse construction conditions, the temporary beam (3) inside the opening is combined with the structural beam (2) outside the opening to form a reverse construction structural beam (8) with a full length within the column span; the intersection of the temporary beam (3) and the structural beam (2) is the position of the opening side wall (1) under normal use conditions; the main reinforcement configuration of the reverse construction structural beam (8) meets the requirements of the two-stage envelope reinforcement of reverse construction and normal use; the main reinforcement of the reverse construction structural beam (8) includes the temporary beam main reinforcement (6) of the temporary beam (3) and the structural beam main reinforcement (4) of the structural beam (2); the structural beam main reinforcement (4) includes the first structural beam main reinforcement in the normal use stage and the second structural beam main reinforcement for reverse construction reinforcement; the first structural beam main reinforcement is anchored into the opening side wall (1) according to the support conditions in the normal use stage, and is welded and connected to the temporary beam main reinforcement (6); the second structural beam main reinforcement is combined with the remaining temporary beam main reinforcement (6) in the temporary beam (3) that has not been welded and connected, and replaced with a full-length steel bar (11).

2. The node structure for combining a temporary beam and a structural beam at an opening of a reverse-construction structure according to claim 1, characterized in that: The width of the reverse-construction structural beam (8) is greater than the beam width calculated under normal use conditions.

3. The node structure for combining a temporary beam and a structural beam at an opening of a reverse-construction structure according to claim 2, characterized in that: The main reinforcement (9) at the corner of the beam width widening portion (10) is embedded in the opening side wall (1) and is welded to the temporary beam main reinforcement (6) to extend the length.

Images