Construction method of pre-arched steel roof truss of super high-rise building

Abstract

The application discloses a kind of super high-rise building pre-arch steel structure roof truss construction methods, belong to the construction technical field of eccentricity inclined super high-rise building. Including the following construction steps: S1, using the way of arc curve arch to design the arch of large-span truss, and according to the construction environment and working condition, the large-span truss is segmented to produce;S2, after the segmented production is completed, several trusses are pre-assembled, and the accuracy of the truss arch and important node is tested;S3, the structure form of support jig is designed, and is laid in the construction site, then the truss is hoisted and assembled;S4, the large-span truss formed by assembling multiple trusses is measured and corrected;S5, the post-welding point is reserved, and the roof truss top surface is covered with soil, and after the soil covering is completed, the truss is welded. The construction method is used to solve the construction difficulties of roof truss involved in eccentricity inclined super high-rise building.

Description

Technical Field

[0001] This invention belongs to the field of construction technology for eccentric and inclined super high-rise buildings, specifically relating to a construction method for a pre-arched steel structure roof truss for super high-rise buildings. Background Technology

[0002] In recent years, with social progress and the rapid development of the construction and steel industries, various types of super high-rise buildings have gradually emerged both domestically and internationally. Due to the unique characteristics of eccentric and inclined super high-rise building structures, special requirements will be placed on various control indicators during the construction process.

[0003] The construction of eccentrically inclined super high-rise building structures presents numerous challenges, one of which involves the construction of the roof truss. While existing technologies offer some reference methods for high-rise building construction, most of these methods employ a top-to-bottom symmetrical contraction design. However, eccentrically inclined super high-rise buildings differ significantly from symmetrically contracted super high-rise buildings in terms of stress analysis and structural design. Therefore, existing roof truss construction methods are insufficient to provide substantial guidance for the construction of roof trusses in eccentrically inclined super high-rise buildings. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a construction method for pre-arched steel structure roof trusses in super high-rise buildings, so as to solve the difficulties in the construction of roof trusses in eccentric and inclined super high-rise buildings.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a construction method for a pre-arched steel structure roof truss of a super high-rise building, comprising the following construction steps: S1. The arching design of the large-span truss is carried out by adopting an arc-shaped curve arching method, and the large-span truss is manufactured in sections according to the construction environment and working conditions. S2. After the segmented fabrication is completed, pre-assemble several trusses to check the accuracy of truss arching and important nodes; S3. Design the structural form of the supporting frame and set it up on the construction site, and then hoist and assemble the truss; S4. Measure and correct the large-span truss formed by assembling multiple truss segments; S5. Reserve welding points for later welding and cover the top surface of the roof truss with soil. After the soil covering is completed, perform welding operations on the truss.

[0006] Furthermore, in step S3, the support frame is a steel pipe support frame, and the steel pipe support frame is set at the splicing end of the adjacent truss.

[0007] Furthermore, the steel pipe support frame includes an outer sleeve, inside which a first spring is provided. Above the first spring is an inner sliding rod, which is slidably connected to the inner side of the outer sleeve. The inner sliding rod has several annular grooves evenly distributed along its length. The upper end of the outer sleeve is provided with an annular mounting plate, and the annular mounting plate has several sets of clamping components around its circumference. The clamping components include a fan-shaped clamp, a connecting sliding rod, a second spring, a mounting base, and a traction rope. One end of the fan-shaped clamp is fixed to one end of the connecting sliding rod, and the other end of the connecting sliding rod passes through the mounting base and is slidably connected to the mounting base. One end of the traction rope is fixed to the outward-facing end of the connecting sliding rod. The second spring is sleeved on the connecting sliding rod and is located between the fan-shaped clamp and the mounting base to press one end of the fan-shaped clamp against the annular groove.

[0008] Furthermore, a sliding sleeve is provided on the outer side of the outer sleeve, and the other end of the traction rope is fixed to one end of the fixed sleeve.

[0009] Furthermore, in step S3, the design of the support frame also includes a stability analysis and assessment of the steel pipe support frame. The assessment method mainly includes the following steps: Calculate the compressive stress of a single steel pipe: Calculate the radius of inertia: Calculate compliance: Where the length coefficient μ=2, and l is the length of the steel pipe; The slenderness threshold λ1 of the Q235 material is 100. If λ > λ1, then the member is a high slenderness member, meaning the critical stress of the steel pipe is σcr = (π 2 E) / λ 2 ; The working stability safety factor of the steel pipe is n=σcr / σ. From the table, the stability safety factor of the compression member of the metal structure is 1.8≤nst≤3.0. If n>nst, then the steel pipe is stable under compression.

[0010] Furthermore, in step S4, measurement points are set at the segment points and mid-span of each truss.

[0011] Furthermore, before conducting the stability analysis of the steel pipe support frame, the analysis also includes the analysis of the concrete floor and the stress analysis of the steel pipe.

[0012] Furthermore, in step S1, the number of segments of the large-span truss is designed based on three factors: the lifting performance of the tower crane, the truss transportation route, and the truss construction site.

[0013] Furthermore, prior to step S1, the process includes modeling the open truss using BIM technology.

[0014] Furthermore, in step S3, the segmented trusses are assembled sequentially from both ends to the middle.

[0015] The beneficial effects of this invention are as follows: (1) This construction method solves the construction problem of roof trusses of eccentric and inclined super high-rise buildings and can provide reference and guidance for the construction of other similar super high-rise structural projects. (2) This construction method can not only improve the efficiency of construction production, but also effectively save the investment of manpower, materials and machinery, ensure the construction quality, and obtain good social and economic benefits. In particular, the research and application of the construction of eccentric and inclined super high-rise steel structures has significantly promoted the development of building steel structure construction technology.

[0016] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0017] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a schematic diagram of the construction process of the roof truss in this invention; Figure 2 This is a schematic diagram of the three-dimensional BIM model of the roof truss in this invention; Figure 3 This is a schematic diagram of the segmentation of a single truss in the roof truss of the present invention; Figure 4-6 This is a schematic diagram of the plan design of the steel pipe support frame during the construction of the roof truss in this invention; Figure 7-10 This is a schematic diagram of the plan layout of the steel pipe support frame during the construction of the roof truss in this invention; Figure 11-12 This is a schematic diagram of the stress analysis of the steel pipe in the roof truss construction method of the present invention; Figure 13 This is a schematic diagram of the truss measurement control points during the construction of the roof truss in this invention; Figure 14 This is a schematic diagram of the design of the pre-arching and post-welding nodes of the roof truss during construction in this invention. Figure 15-18 This is a schematic diagram of the truss installation sequence during the construction of the roof truss in this invention.

[0018] The following labels are shown in the attached diagram: Steel pipe support frame 1, outer sleeve 110, inner slide rod 111, first spring 112, annular mounting plate 113, annular groove 114, fan-shaped locking block 115, connecting slide rod 116, second spring 117, mounting base 118, traction rope 119, sliding sleeve 120. Detailed Implementation

[0019] like Figures 1-18 As shown, the present invention discloses a construction method for a pre-arched steel structure roof truss of a super high-rise building, comprising the following construction steps: S1. An arched design is adopted for the large-span truss, and the truss is fabricated in sections according to the construction environment and working conditions; for example... Figures 2-3 As shown; S2. After the segmented fabrication is completed, pre-assemble several trusses to check the accuracy of truss arching and important nodes; S3. Design the structural form of the supporting frame and arrange it on the construction site, then hoist and assemble the truss; such as Figures 4-13 As shown; S4. Measure and correct the large-span truss formed by assembling multiple truss segments; such as... Figure 16 and Figure 18 As shown; S5. Reserve welding points for later use, and cover the top surface of the roof truss with soil. After the soil covering is completed, perform welding operations on the truss; such as Figure 17 As shown.

[0020] The large-span truss is installed in situ at high altitude using a steel pipe support frame 1. The steel pipe support frame 1 is installed at the segment locations for support. This steel pipe support frame should have an adjustable length function to accommodate trusses of different heights by adjusting its top elevation. This length adjustment also compensates for the length loss during the cutting of the steel pipe support frame 1 during turnover. Traditionally, a top elevation adjustment section is used to adjust the top elevation. However, due to the large installation height of the truss, the top elevation adjustment section requires workers to be elevated to a high position to make adjustments, which poses certain safety hazards and is extremely inconvenient.

[0021] To overcome the inconvenience and drawbacks of traditional steel pipe support frames with top elevation adjustment sections, this technical solution includes an outer sleeve 110, which can be understood as a steel pipe. A first spring 112 is located inside the outer sleeve 110, and an inner sliding rod 111 is located above the first spring 112. The inner sliding rod 111 can be understood as a steel column, and it is slidably connected to the inner side of the outer sleeve 110. The inner sliding rod 111 has several annular grooves 114 evenly distributed along its length. An annular mounting plate 113 is located at the upper end of the outer sleeve 110 and is fixed to the outer sleeve 110. On the ring mounting plate 113, several sets of clamping components are provided around the circumference. The clamping components include a sector-shaped clamping block 115, a connecting slide rod 116, a second spring 117, a mounting base 118, and a traction rope 119. One end of the sector-shaped clamping block 115 is fixed to one end of the connecting slide rod 116. The other end of the connecting slide rod 116 passes through the mounting base 118 and is slidably connected to the mounting base 118. One end of the traction rope 119 is fixed to the outward end of the connecting slide rod 116. The second spring 117 is sleeved on the connecting slide rod 116 and is located between the sector-shaped clamping block 115 and the mounting base 118 to press one end of the sector-shaped clamping block against the annular groove 114.

[0022] When providing support, the lower end of the outer sleeve 110 is first fixed to the ground at a designated location. Then, the traction rope 119 is pulled down to disengage the end of the fan-shaped locking block 115 from the annular groove 114. When erecting the truss, the crane lifts the truss to the designated position and contacts the end of the inner sliding rod 111, which will compress the first spring 112. The first spring 112 is compressed, but its function is to ensure that the end of the inner sliding rod 111 is always in close contact with the truss. After the truss is placed in place, the traction rope 119 is released, and the fan-shaped locking block 115 is pushed into the annular groove under the action of the second spring 117, locking the sliding of the inner sliding rod 111 and thus achieving the support effect.

[0023] This configuration ensures that the inner slide rod 111, under the lifting action of the first spring 112, maintains support and contact with the truss. After installation, simply releasing the traction rope 119 locks the inner slide rod 111, enabling rapid support and installation of the truss. (Traditional top elevation jump stages use threaded connections, requiring manual rotation for tight contact support, which is inefficient. Furthermore, the number of thread turns varies depending on the truss's installation height, making the tight-fitting operation cumbersome and posing safety hazards due to the high-altitude operation.) The second spring 117 further ensures that the inner slide rod 111 maintains tight contact with trusses at different heights, thus improving support and contact. It is also preferable to include a pad 6 at the upper end of the inner slide rod 111 to further enhance the contact effect.

[0024] In one feasible embodiment, a sliding sleeve 120 is slidably sleeved on the outer side of the outer sleeve 110, and the other end of each traction rope 119 is fixed to one end of the fixed sleeve. The sliding sleeve 120 can pull the four sets of traction ropes 119 simultaneously, further improving the installation and support efficiency. It is easy to understand that a locking pin can be provided on the surface of the outer sleeve 110 to limit the position of the sliding sleeve 120, that is, during the installation process, there is no need for manual maintenance of the position of the sliding sleeve 120.

[0025] To further understand this construction method, we will now explain it in conjunction with engineering application examples.

[0026] Example of an eccentric and tilted super high-rise building: Nanning CR Center East Office Building is located in the core area of ​​Nanning's most international ASEAN business district, at the southwest corner of the intersection of Minzu Avenue and Zhongxin Road. The building has 3 underground floors and 86 floors above ground, with a structural height of 384.8m and a top height of 402.65m. The total construction area is 287,000 square meters, and the land area is 5,830.54 square meters.

[0027] The outer frame columns on the south side of the main tower below the 71st floor are inclined to the north by 2 degrees. The south side of the core tube from the 58th to the 61st floor is a sloping wall structure that is inclined to the north. Furthermore, on the south side of the 72nd floor, the outer frame columns are moved northward through a conversion structure to form a stepped terrace. Due to the special shape of the tower structure that tapers from south to north, there is a stress characteristic of being heavier in the north and lighter in the south, which affects the overall stability of the tower.

[0028] The podium building is an auxiliary structure of the Nanning China Resources Center East Office Building. Its structural form is a large-span pre-arched steel roof truss, located on the 5th floor roof of the podium building. There are 10 trusses arranged in a north-south direction. The largest truss span is 33.1m, and the heaviest single truss is 35t. H-shaped connecting steel beams are used between the trusses to increase their lateral stiffness.

[0029] like Figure 2 As shown, the project pioneered the introduction of Building Information Modeling (BIM) technology to improve traditional project management methods and establish a BIM-based construction management model and collaborative work mechanism. In each stage of steel structure design, fabrication, installation, and testing, the collaborative workflows and deliverables of all participants were standardized, personnel responsibilities were clarified, management systems were established, and the integrated application of BIM in the construction phase was explored.

[0030] Based on the key points and difficulties of each stage of the construction of the podium building, we will make full use of the visualization, simulation, and optimization features of BIM technology to solve the problems encountered during the construction process.

[0031] like Figure 3As shown, the arching control is implemented. Based on the characteristics of the large-span truss structure and factors such as the lifting performance and transportation limitations of the M760DX luffing tower crane, the large-span truss is divided into three sections, with the heaviest section weighing approximately 12 tons. The M760DX luffing tower crane can lift 16 tons within a 50m range, and can fully cover the segmented truss, thus meeting the lifting requirements.

[0032] The large-span truss has a mid-span camber of 70mm, which is an arc-shaped camber. After the truss is fabricated in sections, it is pre-assembled to check the camber and node accuracy.

[0033] like Figure 4-6 As shown, the on-site arching control involves a single truss span of 33.1m, a weight of approximately 35t, and a height of 7.8m above the lower floor slab. Therefore, temporary support measures are required for the segmented hoisting of the truss during construction. Considering economic efficiency, convenience, and safety, a steel pipe support frame is used for the truss installation.

[0034] Stress analysis of concrete floor Each formwork frame weighs approximately 10.7 kN, so the load transferred from a single formwork frame to the concrete beam is approximately 213.4 + 10.7 = 224.1 kN. According to the structural design specifications, the additional dead load and live load of the floor slab are 3.5 kN / ㎡ and 5 kN / ㎡, respectively. The bearing capacity of a single concrete secondary beam (400×1000) on the 3rd floor is approximately (3.5+5)×16.3×3.5 = 485 kN, which is greater than the load of the upper formwork frame and truss, thus meeting the requirements.

[0035] The bending moment caused by the self-weight of the concrete floor slab and the load transferred by the formwork at the mid-span of the beam is 822 kN•m, and the bending bearing capacity at the mid-span of the beam is approximately 1290 kN•m. Therefore, the bearing capacity of the beam meets the requirements.

[0036] Stress analysis of steel pipe like Figure 10 As shown, the maximum stress is -2.82 N / mm², which is less than the design strength value of Q235 steel (215 N / mm²), thus meeting the strength requirements. Figure 11 As shown, the support frame has no deformation in the horizontal plane (XY plane) and a maximum deformation of -0.097mm in the Z direction, which meets the specification requirements.

[0037] Carrier stability analysis Compressive stress on a single steel pipe: radius of inertia: Softness: Where the length coefficient μ=2 (one end fixed, one end free), and l is the length of the steel pipe.

[0038] For a Q235 steel member, the critical slenderness ratio λ1 = 100. If λ > λ1, then the member is a high slenderness member, meaning the critical stress of the steel pipe is σ. cr =(π 2 E) / λ2=(π 2 ×210×103) / 151.142MPa=90.73MPa The working stability safety factor of the steel pipe is n=σ cr With σ = 9.2, the safety factor for the stability of the compression member of the metal structure is 1.8 ≤ nst ≤ 3.0, which shows that n > nst. Therefore, the steel pipe is stable under compression.

[0039] For on-site measurement and control, to accurately control the elevation of the arched trusses, a secondary control network for the podium building needs to be established on top of the primary control network. Measurement points are set at the segmental points and mid-span of each truss to ensure the accuracy of the control points. In practice, the measurement results all meet the design and specification requirements.

[0040] The design of the truss welding points is as follows: since the roof truss needs to be covered with 800mm of soil, and considering the stress performance of the truss during its service life, the support on the N-axis is reserved in the detailed design of the steel structure, and welding will be carried out after the roof is covered with soil.

[0041] The construction process involves inserting embedded parts into the truss during civil construction, and then installing the truss after the supporting concrete structure has been poured and reached its design strength.

[0042] In summary, this construction method, based on the design requirement of large-span truss cambering, determines the truss camber to be 70mm, and it is an arc-shaped camber. At the same time, the truss segmentation needs to be considered in terms of the camber position and tower crane conditions. After fabrication, pre-assembly is carried out to check the camber and the accuracy of important nodes of the truss. On the construction site, the camber value of each segment position is determined by CAD arc-shaped camber layout, the top elevation of the supporting frame is obtained, and a 3mm non-elastic compression deformation allowance is reserved.

[0043] Taking into account the weight of the truss, the location of its segments, and the layout of the underlying concrete beams and slabs, the structural form and arrangement of the supporting formwork are designed. Since a single truss is divided into three segments, two supporting formworks are required. The formwork supports are all located on the underlying concrete main beams, which is beneficial for the transfer of construction loads.

[0044] The roof truss is topped with a steel truss composite floor slab and requires soil covering (800mm thick). Considering that soil covering will cause truss deformation, supports are reserved on the N-axis. These supports will be welded after the roof soil covering is completed to meet the load-bearing performance requirements during the service phase.

[0045] The construction benefits of using the above-mentioned construction method for large-span pre-arched steel structure roof trusses are as follows: (1) Improved construction efficiency. The installation of the large-span steel truss of the podium building requires 8 hoisting workers, 12 installation workers, 4 security workers, 4 welders and 8 surveyors per day, which is equivalent to 36 man-days / day. However, the construction personnel input can be reduced by 40% by adopting this construction method, which greatly improves work efficiency.

[0046] (2) Reduce labor costs. According to comprehensive statistics, the input of construction personnel for all truss measurement, installation, welding and other construction is reduced by 40%. With the labor cost of RMB380 / day, the labor cost saved is RMB175,000. Adjustable steel pipe support frame is used instead of traditional frame. With the frame rental cost of RMB6,500 / day and the steel pipe support frame production cost of RMB75,000, the material cost saved is RMB133,000.

[0047] (3) Save equipment shift costs. By rationally planning the stacking and installation sequence of components on the three floors of the podium, a total of 12 shifts of truck cranes, 12 shifts of flatbed trucks, and off-site storage costs were saved. Based on the calculation of 4,100 yuan / shift for a 50t truck crane, 2,200 yuan / shift for a 17m flatbed truck, and 200 yuan / day for a temporary off-site storage area, the equipment shift costs saved amounted to 82,000 yuan.

[0048] (4) Saves time and costs. The use of the construction method speeds up the construction progress, saving a total of 20 days of construction time. After deducting the costs already calculated in points (1) and (2), and assuming an average daily cost of 65,000 yuan for personnel, materials, and machinery, the total cost savings are 65,000 × 20 = 1.3 million yuan. In summary, the total cost savings for personnel, materials, machinery, and management fees can reach 1.69 million yuan.

[0049] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A construction method for a pre-arched steel structure roof truss of a super high-rise building, characterized in that: The construction steps include the following: S1. The arching design of the large-span truss is carried out by adopting an arc-shaped curve arching method, and the large-span truss is manufactured in sections according to the construction environment and working conditions. S2. After the segmented fabrication is completed, pre-assemble several trusses to check the accuracy of truss arching and important nodes; S3. Design the structural form of the supporting frame and set it up on the construction site, and then hoist and assemble the truss; S4. Measure and correct the large-span truss formed by assembling multiple truss segments; S5. Reserve welding points for later welding and cover the top surface of the roof truss with soil. After the soil covering is completed, perform welding operations on the truss. In step S1, the number of segments for the large-span truss is designed based on three factors: the lifting performance of the tower crane, the truss transportation route, and the truss construction site. In step S3, the support frame adopts a steel pipe support frame, which is set at the splicing end of adjacent trusses. The steel pipe support frame includes an outer sleeve, inside which is a first spring. Above the first spring is an inner sliding rod, which is slidably connected to the inner side of the outer sleeve. The inner sliding rod has several annular grooves evenly distributed along its length. The upper end of the outer sleeve has an annular mounting plate, and the annular mounting plate has several sets of clamping components around its circumference. The clamping components include a fan-shaped locking block, a connecting sliding rod, a second spring, a mounting seat, and a traction rope. One end of the fan-shaped locking block is fixed to one end of the connecting sliding rod, and the other end of the connecting sliding rod passes through the mounting seat and is slidably connected to the mounting seat. One end of the traction rope is fixed to the connecting sliding rod facing outward. On one side, the second spring is sleeved on the connecting slide rod and located between the sector-shaped clip and the mounting base, used to press one end of the sector-shaped clip against the annular groove; the outer side of the outer sleeve is slidably sleeved with a sliding sleeve, and the other end of the traction rope is fixed to one end of the sliding sleeve; when performing the support function, firstly, the lower end of the outer sleeve is fixed to the ground at the designated position, and then the traction rope is pulled down to make the end of the sector-shaped clip disengage from the annular groove. Then, when erecting the truss, the crane lifts the truss to the designated position and then contacts the end of the inner slide rod, which will squeeze the first spring. The first spring is compressed, and under the action of the first spring, it will always ensure that the end of the inner slide rod is in close contact with the truss. After the truss is placed in place, the traction rope is released, and the sector-shaped clip is pushed into the annular groove under the action of the second spring, locking the sliding of the inner slide rod to achieve support; in step S4, measuring points are set at the segment and mid-span of each truss.

2. The construction method for a pre-arched steel structure roof truss of a super high-rise building according to claim 1, characterized in that: In step S3, the design of the support frame also includes the stability analysis and judgment of the steel pipe support frame. The judgment method mainly includes the following steps: Calculate the compressive stress of a single steel pipe: Calculate the radius of inertia: Calculate compliance: Where the length coefficient μ=2, and l is the length of the steel pipe; The slenderness threshold λ1 of the Q235 material is 100. If λ > λ1, then the member is a high slenderness member, meaning the critical stress of the steel pipe is σ. cr =(π 2 E) / λ 2 ; The working stability safety factor of the steel pipe is n=σ cr / σ, from the table we can find that the stability safety factor of the compression member of the metal structure is 1.8≤nst≤3.

0. If n>nst, then the steel pipe is stable under compression.

3. The construction method for a pre-arched steel structure roof truss of a super high-rise building according to claim 2, characterized in that: Before conducting the stability analysis of the steel pipe support frame, the analysis also includes the analysis of the concrete floor and the stress analysis of the steel pipe.

4. The construction method for a pre-arched steel structure roof truss of a super high-rise building according to claim 1, characterized in that: Before step S1, the process also includes modeling the open truss using BIM technology.

5. The construction method for a pre-arched steel structure roof truss of a super high-rise building according to claim 1, characterized in that: In step S3, the segmented trusses are assembled sequentially, starting from the two ends and then moving to the middle.

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