Installation construction method of steel box girder based on folding arm crane

Abstract

The present invention provides a steel box girder installation construction method based on folding arm crane hoisting, which belongs to the technical field of steel box girder installation construction. The method includes the following steps: crane selection and most unfavorable working condition analysis, hoisting area foundation bearing capacity analysis, early hoisting, consolidation pier hoisting and temporary support installation, construction segmentation, longitudinally divided into 7 sections, horizontally divided into 4 sections, a total of 28 sections, namely A1-A7 section, B1-B7 section, C1-C7 section, D1-D7 section, hoisting construction, and hoisting. By optimizing the installation process and crane station position, not only can the hoisting of the steel box girder be completed efficiently, but also the installation period is shortened; through the safety monitoring and early warning system of the folding arm crane, real-time monitoring and risk early warning of the installation process are realized, which greatly reduces the probability of safety accidents.

Description

Technical Field

[0001] The invention relates to the technical field of steel box girder installation and construction, and in particular to a steel box girder installation and construction method based on folding arm crane hoisting. Background Art

[0002] With the rapid development of modern engineering construction, large folding arm cranes, as important lifting equipment, play an indispensable role in ports, bridges, wind power, petrochemicals and other fields. Its unique folding arm structure and powerful lifting capacity enable it to flexibly and efficiently complete heavy lifting tasks in complex working environments. However, the installation process of large folding arm cranes is complicated, involving multiple links such as limited space operations, high-altitude operations, precision debugging and safety risk control, and has extremely high requirements for installation technology and installation site environment. Therefore, conducting research on the efficient and safe installation technology of large folding arm cranes in limited spaces is of great significance for improving installation efficiency, reducing construction costs and ensuring operation safety.

[0003] At present, there are dozens of models of truck cranes produced by more than a dozen companies in Sweden, Italy, Germany, the United States, Japan and other countries, mainly in Europe. Each company has formed a product system with diversified functions, serialized varieties, and integrated electromechanical and hydraulic control. With the acceleration of scientific and technological progress, the production of truck cranes in various countries in the world has developed greatly. From the initial small single product, it has developed into a full range of advanced products with high torque, multi-function, beautiful appearance, simple operation, safe use, and wired or wireless remote control. It can be said that the development of truck cranes has entered a mature stage. Truck cranes can be divided into straight arm truck cranes and folding arm truck cranes. Straight arm truck cranes strictly control the lifting and lowering of the lifting objects by telescopic means. It can also expand the working depth and work radius by lengthening the wire rope. It is suitable for places with wider space. Folding arm truck cranes have higher working efficiency, more precise work, can expand business, and are more flexible in dealing with narrow spaces, but the total cost is high and the accessories are expensive. When transporting goods, the folding arm crane can shrink the entire boom, the space utilization rate will be higher, and the operation can be completed in a limited space. Therefore, it is necessary to design a steel box girder installation construction method based on folding arm crane hoisting. Summary of the invention

[0004] The purpose of the present invention is to provide a steel box girder installation construction method based on folding arm crane hoisting, so as to solve the technical problems that the existing steel box girder installation construction period is long and requires a large construction space.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A steel box girder installation construction method based on folding arm crane hoisting comprises the following steps:

[0007] Step 1: Crane selection and most unfavorable working condition analysis;

[0008] Step 2: Bearing capacity analysis of the foundation in the lifting area;

[0009] Step 3: Preliminary hoisting, consolidation pier hoisting and temporary support installation;

[0010] Step 4: Divide the construction into sections, which are divided into 7 sections vertically and 4 sections horizontally, a total of 28 sections, namely A1-A7, B1-B7, C1-C7, and D1-D7;

[0011] Step 5: Carry out hoisting construction and complete the hoisting.

[0012] Furthermore, in step 1: according to the characteristics of the steel structure and the weight statistics of the segments, combined with the elevation of the steel box beam in the design drawings and the actual ground elevation on site, it is concluded that the height of the steel box beam is 9.5-10.5m, the maximum weight of the steel box hoisting component is 29.65t, and two 150-ton folding arm cranes are selected for hoisting;

[0013] 1) Determine the lifting height H required for hoisting:

[0014] H = height of steel box girder in place + height of sling + safety distance of hook;

[0015] 2) Determine the length of the boom:

[0016] According to the principle that the hoisting height of the crane shall not be less than H, taking into account the height of the crane's large hook and the limit height, it was preliminarily determined that the boom length would adopt a five-section boom, the heaviest section of the steel box girder is 29.65t, the swing radius during operation is 13m, the five-section boom, and the lifting capacity is 31×2*75%=46.5>29.65×1.1*1.25=40.77t. Two 150t folding arm cranes meet the requirements.

[0017] Furthermore, the specific process of the most unfavorable working condition analysis in step 1 is:

[0018] The most unfavorable working condition is the lifting of the C6 section of the fifth section of the D ramp. The truck crane is located on the hardened foundation. The lifting beam section weighs 29.65t. During the lifting process, the crane arm collides with the box beam because the distance is close to the set value during the rotation process. To prevent this from happening, the most unfavorable working condition C6 section is analyzed. The crane station is located on the side of the bridge. The swing radius during operation is 13m, with a five-section arm and a lifting capacity of 31×2*75%=46.5>29.65×1.1*1.25=40.77t, which meets the lifting requirements.

[0019] Furthermore, the specific process of step 2 is:

[0020] The heaviest load condition is 300t truck crane lifting 38.68t, 300t crane deadweight 54.99t+100t=154.99t, counterweight 100t, 2.5m*2.5m pads are used. If the foundation bearing capacity of the steel box girder of the largest beam section to be lifted meets the requirements, the rest are met;

[0021] The contact area between a single crane and the ground is the contact area between two pads, which is 2.5m×2.5m×2=12.5m 2 , the maximum reaction force can be calculated according to the following formula:

[0022] R max =a×(P+Q)(1.1)

[0023] Where P is the deadweight of the crane, Q is the lifting weight, and a is the dynamic load coefficient. Calculated as a=1.1, we get:

[0024] R max =1.1×(154.99t+38.68t)×10N / kg=2130.37KN(1.2)

[0025] The uniformly distributed load on the site during crane lifting is:

[0026] P=R max / S=2130.37KN / 12.5m 2 =170.43KPa(1.3)

[0027] The bearing capacity of the foundation is required to be hardened to 250KPa>170.43KPa, which meets the requirements of automobile crane lifting. In order to balance the different settlement problems of foundation and roadbed, a 2.5*2.5m roadbed box is added under the non-roadbed crane legs, which is provided by the crane to reduce the influence of settlement factors.

[0028] Furthermore, the specific process of step 3 is:

[0029] The consolidation pier is hoisted by a 100T crane, with a turning radius of 8m, a boom length of 31m, a lifting capacity of 31.8 tons, and a beam section weight of 2.16×1.1=2.38t<31.8t, which meets the hoisting requirements. Before hoisting, a guy rope is arranged at the diagonal position of the lower part of the consolidation pier to facilitate the hoisting angle control. It needs to be installed in advance, poured and reached the design strength before the subsequent beam section hoisting and temporary support installation. There are 6 sets of temporary supports in the fifth unit of D ramp.

[0030] Furthermore, the specific process of step 5 is:

[0031] Step 5.1: The beam sections A7, B7, C7, and D7 are hoisted by a 300-ton truck crane in the order of B7→A7→C7→D7. The crane body is perpendicular to the longitudinal bridge design line, and the rear of the crane faces the bridge position. Four sections are hoisted without moving the crane. The turning radius is 18m, the arm length is 40.3m, and the lifting capacity is 40 tons. The heaviest beam section is 26.9×1.1=29.59t<40t, which meets the hoisting requirements and can be hoisted;

[0032] Step 5.2: The A6-B6 beam section is first unloaded by two 150-ton folding arm cranes. Before installation, the cantilever arm and the main beam are made into an integral whole using a horse plate. The turning radius is 9-13m, the arm length is five-section arm, the highest is 13 meters, and the lifting capacity is 30 tons. The heaviest beam section is 29.34×1.1=32.27t<30×2×75%=45t, which meets the lifting requirements and can be unloaded. The A6+B6 beam section is hoisted by two 150-ton folding arm cranes. The turning radius is 9-13m, the arm length is five-section arm, the highest is 13 meters, and the lifting capacity is 30 tons. The beam section weight is (29.34+7.44)×1.3=40.46t<30×2×75%=45t, which meets the lifting requirements and can be hoisted;

[0033] Step 5.3: The C6 and D6 beam sections are hoisted by two 150-ton folding arm cranes, with a slewing radius of 9-13m and a five-section arm length, a maximum of 13 meters, and a lifting capacity of 30 tons. The heaviest beam section is C6: 29.65×1.1=32.62t<30×2×75%=45t, which meets the hoisting requirements and can be hoisted;

[0034] Step 5.4: The A5-B5 beam section is unloaded by two 150-ton folding arm cranes. Before installation, the cantilever arm and the main beam are made into an integral whole using a horse plate. The turning radius is 9-13m, the arm length is five-section arm, the highest is 13 meters, and the lifting capacity is 30 tons. The heaviest beam section is 27.06×1.1=29.77t<30×2×75%=45t, which meets the lifting requirements and can be unloaded. The A5+B5 beam section is hoisted by two 150-ton folding arm cranes. The turning radius is 9-13m, the arm length is five-section arm, the highest is 13 meters, and the lifting capacity is 30 tons. The beam section weight is (27.06+6.86)×1.1=37.31t<30×2×75%=45t, which meets the lifting requirements and can be hoisted;

[0035] Step 5.5: The C5 and D5 beam sections are hoisted by two 150-ton folding arm cranes, with a slewing radius of 13m and a five-section arm length, a maximum of 13m, and a lifting capacity of 30 tons. The heaviest beam section is: 27.35×1.1=30.09t<30×2×75%=45t, which meets the hoisting requirements and can be hoisted;

[0036] Step 5.6: The beam sections A4-D4 and A3-D3 are hoisted by a 300-ton truck crane, with a slewing radius of 14m / 18m, a boom length of 40.3m, and a lifting capacity of 55 / 40 tons. The heaviest beam section is the C3 beam section: 36.59×1.1=40.25t<55t, which meets the hoisting requirements and can be hoisted. The hoisting sequence is B4→A4→C4→D4→B3→A3→C3→D3;

[0037] Step 5.7: The B2 beam section is hoisted by a 300-ton truck crane, with a slewing radius of 14m, a boom length of 40.3m, a lifting capacity of 55 tons, and a beam section weight of 38.29×1.1=42.12t<55t, which meets the hoisting requirements and can be hoisted;

[0038] Step 5.8: The A2, C2, D2, and A1-D1 beam sections are hoisted by a 300-ton truck crane. The crane station is located at the exit of the Inner Ring Expressway, and the beam truck is parked on the emergency lane of the Inner Ring Expressway. The turning radius is 14m / 18m, the arm length is 40.3m, and the lifting capacity is 55 / 40 tons. The heaviest beam section is the C2 beam section: 38.68×1.1=42.55t<55t, which meets the hoisting requirements and can be hoisted. The hoisting sequence is C2→D2→A2→B1→C1→D1→A1.

[0039] Furthermore, in step 5, the specific process of hoisting and adjusting the steel box girder is as follows:

[0040] Check whether the crane station is safe and whether there are any dangerous sources around. Connect the wire rope to the lifting lug with a snap ring and connect the other end of the wire rope to the main hook. To ensure that the wire rope is not broken, the wire rope hoisting angle should not be less than 60°;

[0041] Before the official lifting operation, the truck crane should conduct a trial lifting of the steel box girder. Before the trial lifting, the personnel participating in the lifting should strictly check the performance of the lifting lugs, lifting machinery and rigging according to the division of labor. Only after confirming that they meet the requirements of the plan can the trial lifting be carried out. Before lifting, two cable wind ropes are set at both ends of the beam section, and then each rope is controlled by two workers to control the state of the beam section in the air. After the hook and the lifting lug are hung, start to lift slowly to 100mm from the starting position, keep for more than 10 minutes, and confirm whether the center of gravity position of the lifting point meets the box girder balance; if not, adjust the length of the wire rope by adding lifting rings to ensure that the center of gravity of the steel beam is in the center until the box girder maintains a balanced state during the lifting process, and check the stability of the crane, the reliability of the brake, the balance of the steel box girder, and the firmness of the binding. After confirmation, the formal lifting can be carried out;

[0042] The box girder is hoisted by a truck crane, and the beam section leveling measures are as follows:

[0043] (1) According to the structural form and weight of the box girder during hoisting, calculate the center of gravity of the beam section and reasonably arrange the lifting lugs at both ends of each box girder section;

[0044] (2) According to the longitudinal slope of the box girder, the pre-camber value and the on-site lifting conditions, select appropriate lifting wire ropes, shackles, chain hoists and other tools, and determine the length of the wire ropes at both ends of the hook;

[0045] (3) When the hoisting beam section is close to the working surface, it is connected by a hand chain hoist and the position of the steel box girder is controlled by adjusting the length of the hand chain hoist;

[0046] (4) During the installation process of the steel box girder, its state needs to be constantly adjusted, and rough and fine adjustments are performed to ensure that the steel box girder is installed smoothly in place;

[0047] The precise positioning and adjustment of the steel box girder are as follows:

[0048] (1) Before lifting, two cables are tied to the segment to control the state of the segment in the air. After the segment hooks are hung on the lifting points of the steel box girder top plate, the safety officer will inspect and accept them. After passing the inspection, the lifting commander will command the crane driver to slowly lift the segment. When the predetermined lifting height is reached, it will exceed the top surface of the temporary support by more than 1m. The lifting commander will command the crane to slowly rotate the boom to the top of the predetermined installation position. The crane will slowly drop the hook to lift the segment to 10cm above the top surface of the temporary support and stop. Then, the steel box girder will be initially positioned by manual reference to the edge line and center line of the bottom plate of the steel box girder released in advance, and the crane will continue to slowly drop the hook to the installation position.

[0049] Line type horizontal and vertical adjustment control:

[0050] The linear control of the steel box girder should first be carried out in the factory. Before hoisting, control points and lines are set on the permanent piers and temporary piers, and control points and lines are set accordingly on the steel box girder. When the steel box girder is installed, the center line and longitudinal distance are controlled by the control points and lines set on the piers in advance corresponding to the points and lines set on the steel box girder. At the same time, the measurement instrument is used for synchronous monitoring. The elevation of the steel box girder is calculated by setting out and directly reflected in the height of the adjustment pipe. After the center line, longitudinal distance and beam elevation are adjusted, welding can be carried out at the joints of each section of the box body to ensure the smooth linear shape of the steel box girder.

[0051] During the deepening of the steel box girder drawings, the construction pre-arch is added to the original design pre-arch, and the temporary support elevation is in line with the actual beam bottom line shape. After the on-site installation is completed and the support is removed, the design pre-arch value is reached under the action of gravity;

[0052] Temporary measures for steel box girder placement:

[0053] After the steel box girder is temporarily in place, the bottom plate of the steel box girder and the contact surface of the temporary support are fully welded to prevent the steel box girder from slipping and overturning. The in-place beam section is temporarily fixed with a horse plate at the interface of the steel box girder section to prevent the displacement of the steel box girder section. After the hoisting and welding are completed, the temporary fixing measures will be removed.

[0054] Furthermore, during the suspension installation of the steel box girder in step 5, there are suspension conditions during the hoisting of the third section of the D ramp and the ninth section of the main line, and during the hoisting of the cantilever structure; when the automobile crane is used to hoist the suspended beam section, after the steel box girder is in place, the horse plate is welded at the joint for positioning using an aerial work vehicle, and the horse plate is arranged and assembled. At the same time, 40b I-beams are used to strengthen the top plate and bottom plate, with two top and bottom plates. After the above work is completed, the automobile crane can unload the loose hook, and after all the ring welds are completed, the aerial work vehicle is used to remove the horse plate and grind and repair the welds;

[0055] The saddle plate should be made of a rectangular steel plate of 200mm×100mm×10mm, and arranged one every 300mm along the segment interface direction. The welding foot of the saddle plate and the component should not be less than 6mm.

[0056] The present invention has the following beneficial effects due to the adoption of the above technical solution:

[0057] The present invention can not only efficiently complete the hoisting of the steel box girder but also shorten the installation period by optimizing the installation process and the crane station position; through the safety monitoring and early warning system of the folding arm crane, real-time monitoring and risk early warning of the installation process are realized, which greatly reduces the probability of safety accidents; through the design of temporary supports, the steel box girder positioning points are increased, the installation accuracy is improved, and a strong guarantee is provided for the precise installation of large folding arm cranes; for the construction environment in a limited space, this subject ensures stable operation under such environmental conditions by taking appropriate protective measures and adjustment strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is the fifth joint elevation view of the D ramp of the present invention;

[0059] Figure 2 This is a schematic diagram of the fifth segmented structure of the D ramp of the present invention;

[0060] Figure 3 It is a structural schematic diagram of the hoisting step 1 of the present invention;

[0061] Figure 4 It is a structural schematic diagram of hoisting step 2 of the present invention;

[0062] Figure 5 It is a structural schematic diagram of hoisting step 3 of the present invention;

[0063] Figure 6It is a structural schematic diagram of hoisting step 4 of the present invention;

[0064] Figure 7 It is a structural schematic diagram of hoisting step 5 of the present invention;

[0065] Figure 8 It is a structural schematic diagram of hoisting step 6 of the present invention;

[0066] Fig. 9 It is a structural schematic diagram of hoisting step 7 of the present invention;

[0067] Fig.10 It is a structural schematic diagram of hoisting step 8 of the present invention. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are only for the purpose of enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

[0069] The University Town Double-track Tunnel Project is located on the north side of the existing University Town Tunnel in Shapingba District. It starts from the Xishan Interchange of Pingshan Avenue in the west, extends eastward through Zhongliang Mountain, and ends at Tianli Road east of the Hongcaofang Interchange of the Inner Ring Road. The total length of the line is about 5.9km, and the main project includes one extra-long tunnel (the University Town Double-track Tunnel, 4.1km long) and one interchange (Hongcaofang Interchange, and the Yanshan Road Interchange is reserved for the long term).

[0070] From the starting point of the road to the west side of the inner ring of Hongcaofang Interchange (K5+200-K5+970), an urban expressway is used with a design speed of 80km / h; from the west side of the inner ring of Hongcaofang Interchange to the east side of the inner ring (K5+970-K6+320), an urban trunk road is used with a design speed of 60km / h; from the east side of the inner ring of Hongcaofang Interchange to the end of the road (K6+320-K6+840), an urban trunk road is used with a design speed of 50km / h.

[0071] The project includes 17 steel-concrete composite bridges, including 2 D ramps, 9 main line widening bridges, 1 A, B, and C ramps, 2 main line bridges, and 1 overpass. The construction is divided into 7 sections longitudinally and 4 sections horizontally, for a total of 28 sections. Figure 2 shown.

[0072] The fifth leg of the D ramp, this bridge passes under the main line and over the roundabout. The cross section is a single-box single-chamber structure with cantilever arms on both sides. The plate rib stiffening box is longitudinally arranged with a solid-belt cross-diaphragm and a frame-type cross-diaphragm every 2.5m along the center line of the route. Figure 1 The segment weight table is shown in Table 1:

[0073] Table 1 is the segment weight table. Transport route: D ramp, fifth link, CCCC Worldlink Chongqing Processing Base → S5 Jiuyong Expressway → G93

[0074]

[0075] Chengdu-Chongqing Ring Expressway → G5001 Chongqing Ring Expressway → G75 Lanhai Expressway → North Ring Interchange → Yanggongqiao Interchange → Bridge site.

[0076] Construction pre-arch: This bridge contains two line types: horizontal curve and vertical curve. During the drawing deepening process, the horizontal curve is deepened according to the design, and the vertical curve is composed of three parts: longitudinal slope + design pre-arch + construction pre-arch. The longitudinal slope + design pre-arch is the design drawing line type. The processing and manufacturing take into account the on-site hoisting, transportation, storage, and on-site installation. The steel box girder has different degrees of deflection. In order to ensure the overall line type of the bridge on-site installation, the construction pre-arch is added in the process of drawing deepening. The construction pre-arch value is determined according to the bridge length combined with the design pre-arch, and the comprehensive deflection of the construction pre-arch is used to ensure the overall line type of the bridge.

[0077] Analysis of project characteristics and key points

[0078] Key points and difficulties: Part of the project passes under a viaduct with a clearance height of 14 meters. After the steel box girder is in place, the bridge deck has a clearance of 2 meters, and the lifting environment is limited.

[0079] Countermeasures: The underpass is hoisted by two folding arm cranes, and the inner arc side box and the cantilever arm are assembled and hoisted as a whole to avoid hoisting across supports and bridges.

[0080] Temporary support structure: Steel pipe columns are made of φ=426*8mm steel pipes, horizontal braces and diagonal braces are made of 12.6# channel steel, and cross beams are made of double-jointed 25b I-beams (steel pipe columns and adjustment pipe support parts are reinforced), auxiliary materials are made of 10mm and 20mm steel plates, and a temporary construction platform is set on the top of the support. The connection between the support structures is welded, with 8mm weld feet. Φ14 steel mesh and support embedded parts are embedded in the support foundation. The foundation thickness is 0.6m, and the support foundation is made of C30 concrete.

[0081] Crane selection and the most unfavorable working conditions

[0082] 1. Crane selection

[0083] According to the characteristics of the steel structure and the weight statistics of the segments, combined with the elevation of the steel box beam in the design drawings and the actual ground elevation on site, it is concluded that the height of the steel box beam is about 10m. The maximum weight of the main hoisting components of the steel box beam is 29.65t. It is planned to use two 150-ton folding arm cranes for hoisting.

[0084] 1) Determine the lifting height H required for hoisting:

[0085] H (maximum) = steel box girder placement height (10m) + sling height (2m) + hook safety distance (1m)

[0086] 2) Determine the length of the boom

[0087] According to the principle that the hoisting height of the crane shall not be less than H, considering the crane's large hook height and limit height, the initial determination of the boom length is to use a five-section boom. The heaviest section of the steel box girder is 29.65t, the swing radius during operation is 13m, the five-section boom, the lifting capacity is 31×2*75%=46.5>29.65×1.1*1.25=40.77t, and two 150t folding arm cranes meet the requirements.

[0088] Worst case analysis

[0089] The most unfavorable working condition is the lifting of the C6 section of the fifth section of the D ramp. The truck crane is located on the hardened foundation, and the lifting beam section weighs 29.65t. During the lifting process, the crane arm may collide with the box beam due to the short distance or short arm length. To prevent this from happening, the most unfavorable working condition C6 section is analyzed. The crane station is located on the side of the bridge. The swing radius during operation is 13m, with a five-section arm and a lifting capacity of 31×2*75%=46.5>29.65×1.1*1.25=40.77t, which meets the lifting requirements.

[0090] Foundation bearing capacity of lifting area

[0091] The heaviest load condition for this hoisting is 300t truck crane hoisting 38.68t, 300t crane deadweight 54.99t + 100t = 154.99t (counterweight 100t), using 2.5m*2.5m pads. If the foundation bearing capacity of the steel box girder of the largest beam section to be hoisted meets the requirements, the rest are all met.

[0092] The contact area between a single crane and the ground is the contact area between two pads, which is 2.5m×2.5m×2=12.5m 2 , the maximum reaction force can be calculated according to the following formula:

[0093] R max =a×(P+Q)(1.1)

[0094] Where P is the deadweight of the crane, Q is the lifting weight, and a is the dynamic load coefficient. Calculated as a=1.1, we get:

[0095] R max =1.1×(154.99t+38.68t)×10N / kg=2130.37KN(1.2)

[0096] The uniformly distributed load on the site during crane lifting is:

[0097] P=R max / S=2130.37KN / 12.5m 2 =170.43KPa(1.3)

[0098] The bearing capacity of the foundation is required to be hardened to 250KPa>170.43KPa, which meets the requirements of automobile crane lifting. In order to balance the settlement of the foundation and the roadbed, a 2.5*2.5m roadbed box (built in the crane) is added under the non-roadbed crane legs to reduce the influence of settlement factors.

[0099] Hoisting process:

[0100] Preliminary hoisting: 1. Consolidation pier hoisting, using a 100T crane. The turning radius is 8m, the arm length is 31m, the lifting capacity is 31.8 tons, and the beam section weight is 2.16×1.1=2.38t<31.8t, which meets the hoisting requirements and can be hoisted. (Before hoisting, arrange the cable wind rope at the diagonal position of the lower part of the consolidation pier to facilitate the hoisting angle control). Note: It needs to be installed in advance, and the subsequent beam section hoisting will be carried out after pouring and reaching the design strength. 2. Temporary support installation, a total of 6 sets of temporary supports for the fifth joint of D ramp.

[0101] Step 1: A7, B7, C7, D7 beam sections are hoisted by a 300-ton truck crane in the order of B7→A7→C7→D7. The crane body is perpendicular to the longitudinal bridge design line, and the rear of the crane faces the bridge position. The four sections are hoisted without moving the crane. The turning radius is 18m, the arm length is 40.3m, and the lifting capacity is 40 tons. The heaviest beam section is 26.9×1.1=29.59t<40t, which meets the hoisting requirements and can be hoisted. Figure 3 shown.

[0102] Step 2: The A6-B6 beam section is first unloaded by two 150-ton folding arm cranes. Before installation, the cantilever arm and the main beam are made into an integral whole using a horse plate. The turning radius is 9-13m, the arm length is a five-section arm (up to 13 meters), the lifting capacity is 30 tons, and the heaviest beam section is 29.34×1.1=32.27t<30×2×75%=45t, which meets the lifting requirements and can be unloaded.

[0103] The A6+B6 beam section is hoisted by two 150-ton folding arm cranes, with a slewing radius of 9-13m and a five-section arm (maximum 13m), a lifting capacity of 30 tons, and a beam section weight of (29.34+7.44)×1.3=40.46t<30×2×75%=45t, which meets the hoisting requirements and can be hoisted. Figure 4 shown.

[0104] Step 3: C6 and D6 beam sections are hoisted by two 150-ton folding arm cranes, with a slewing radius of 9-13m and a five-section arm (maximum 13 meters). The lifting capacity is 30 tons. The heaviest beam section is C6: 29.65×1.1=32.62t<30×2×75%=45t, which meets the hoisting requirements and can be hoisted. Figure 5 shown.

[0105] Step 4: The A5-B5 beam section is unloaded by two 150-ton folding arm cranes. Before installation, the cantilever arm and the main beam are made into an integral whole using a horse plate. The turning radius is 9-13m and the arm length is five-section (maximum 13 meters). The lifting capacity is 30 tons. The heaviest beam section is 27.06×1.1=29.77t<30×2×75%=45t, which meets the lifting requirements and can be unloaded.

[0106] The A5+B5 beam section is hoisted by two 150-ton folding arm cranes, with a slewing radius of 9-13m and a five-section arm (maximum 13m), a lifting capacity of 30 tons, and a beam section weight of (27.06+6.86)×1.1=37.31t<30×2×75%=45t, which meets the hoisting requirements and can be hoisted. Figure 6 shown.

[0107] Step 5: The C5 and D5 beam sections are hoisted by two 150-ton folding arm cranes, with a slewing radius of 13m and a five-section arm (maximum 13m). The lifting capacity is 30 tons, and the heaviest beam section is: 27.35×1.1=30.09t<30×2×75%=45t, which meets the hoisting requirements and can be hoisted. Figure 7 shown.

[0108] Step 6: The A4-D4 and A3-D3 beam sections are hoisted by a 300-ton truck crane, with a slewing radius of 14m / 18m, a boom length of 40.3m, and a lifting capacity of 55 / 40 tons. The heaviest beam section is the C3 beam section: 36.59×1.1=40.25t<55t, which meets the hoisting requirements and can be hoisted. The hoisting sequence is B4→A4→C4→D4→B3→A3→C3→D3, such as Figure 8 shown.

[0109] Step 7: The B2 beam section is hoisted by a 300-ton truck crane, with a slewing radius of 14m, a boom length of 40.3m, a lifting capacity of 55 tons, and a beam section weight of 38.29×1.1=42.12t<55t, which meets the hoisting requirements and can be hoisted. Fig. 9 shown.

[0110] Step 8: A2, C2, D2, A1-D1 beam sections are hoisted by a 300-ton truck crane (the crane station is at the exit of the inner ring expressway, and the beam truck is parked on the emergency lane of the inner ring expressway). The turning radius is 14m / 18m, the arm length is 40.3m, and the lifting capacity is 55 / 40 tons. The heaviest beam section is C2: 38.68×1.1=42.55t<55t meets the hoisting requirements and can be hoisted. The hoisting sequence is C2→D2→A2→B1→C1→D1→A1, such as Fig.10 shown.

[0111] The specific process of hoisting and adjusting the steel box girder is as follows:

[0112] Check whether the crane station is safe and whether there are any dangerous sources around. Connect the wire rope to the lifting lug with a snap ring and connect the other end of the wire rope to the main hook. To ensure that the wire rope is not broken, the wire rope hoisting angle should not be less than 60°;

[0113] Before the official lifting operation, the truck crane should conduct a trial lifting of the steel box girder. Before the trial lifting, the personnel participating in the lifting should strictly check the performance of the lifting lugs, lifting machinery and rigging according to the division of labor. Only after confirming that they meet the requirements of the plan can the trial lifting be carried out. Before lifting, two cable wind ropes are set at both ends of the beam section, and then each rope is controlled by two workers to control the state of the beam section in the air. After the hook and the lifting lug are hung, start to lift slowly to 100mm from the starting position, keep for more than 10 minutes, and confirm whether the center of gravity position of the lifting point meets the box girder balance; if not, adjust the length of the wire rope by adding lifting rings to ensure that the center of gravity of the steel beam is in the center until the box girder maintains a balanced state during the lifting process, and check the stability of the crane, the reliability of the brake, the balance of the steel box girder, and the firmness of the binding. After confirmation, the formal lifting can be carried out;

[0114] The box girder is hoisted by a truck crane, and the beam section leveling measures are as follows:

[0115] (1) According to the structural form and weight of the box girder during hoisting, calculate the center of gravity of the beam section and reasonably arrange the lifting lugs at both ends of each box girder section;

[0116] (2) According to the longitudinal slope of the box girder, the pre-camber value and the on-site lifting conditions, select appropriate lifting wire ropes, shackles, chain hoists and other tools, and determine the length of the wire ropes at both ends of the hook;

[0117] (3) When the hoisting beam section is close to the working surface, it is connected by a hand chain hoist and the position of the steel box girder is controlled by adjusting the length of the hand chain hoist;

[0118] (4) During the installation process of the steel box girder, its state needs to be constantly adjusted, and rough and fine adjustments are performed to ensure that the steel box girder is installed smoothly in place;

[0119] The precise positioning and adjustment of the steel box girder are as follows:

[0120] (1) Before lifting, two cables are tied to the segment to control the state of the segment in the air. After the segment hooks are hung on the lifting points of the steel box girder top plate, the safety officer will inspect and accept them. After passing the inspection, the lifting commander will command the crane driver to slowly lift the segment. When the predetermined lifting height is reached, it will exceed the top surface of the temporary support by more than 1m. The lifting commander will command the crane to slowly rotate the boom to the top of the predetermined installation position. The crane will slowly drop the hook to lift the segment to 10cm above the top surface of the temporary support and stop. Then, the steel box girder will be initially positioned by manual reference to the edge line and center line of the bottom plate of the steel box girder released in advance, and the crane will continue to slowly drop the hook to the installation position.

[0121] Line type horizontal and vertical adjustment control:

[0122] The linear control of the steel box girder should first be carried out in the factory. Before hoisting, control points and lines are set on the permanent piers and temporary piers, and control points and lines are set accordingly on the steel box girder. When the steel box girder is installed, the center line and longitudinal distance are controlled by the control points and lines set on the piers in advance corresponding to the points and lines set on the steel box girder. At the same time, the measurement instrument is used for synchronous monitoring. The elevation of the steel box girder is calculated by setting out and directly reflected in the height of the adjustment pipe. After the center line, longitudinal distance and beam elevation are adjusted, welding can be carried out at the joints of each section of the box body to ensure the smooth linear shape of the steel box girder.

[0123] During the deepening of the steel box girder drawings, the construction pre-arch is added to the original design pre-arch, and the temporary support elevation is in line with the actual beam bottom line shape. After the on-site installation is completed and the support is removed, the design pre-arch value is reached under the action of gravity;

[0124] Temporary measures for steel box girder placement:

[0125] After the steel box girder is temporarily in place, the bottom plate of the steel box girder and the contact surface of the temporary support are fully welded to prevent the steel box girder from slipping and overturning. The in-place beam section is temporarily fixed with a horse plate at the interface of the steel box girder section to prevent the displacement of the steel box girder section. After the hoisting and welding are completed, the temporary fixing measures will be removed.

[0126] During the installation of the steel box girder suspension, there are suspension conditions during the hoisting of the third section of the D ramp and the ninth section of the main line, as well as the hoisting of the cantilever structure. When the truck crane is used to hoist the suspended beam section, after the steel box girder is in place, the horse plate is welded to the joint for positioning using an aerial work vehicle, and the horse plate is arranged and assembled. At the same time, 40b I-beams are used to strengthen the top and bottom plates, with two top and bottom plates. After the above work is completed, the truck crane can unload the loose hook. After the ring welds are all completed, the aerial work vehicle is used to remove the horse plate and grind and repair the welds.

[0127] The saddle plate should be made of a rectangular steel plate of 200mm×100mm×10mm, and arranged one every 300mm along the segment interface direction. The welding foot of the saddle plate and the component should not be less than 6mm.

[0128] Matters not covered by the present invention are known technologies.

[0129] 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 modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. The steel box girder installation construction method based on folding arm crane is characterized by: The method comprises the following steps: Step 1: Crane selection and most unfavorable working condition analysis; Step 2: Bearing capacity analysis of the foundation in the lifting area; Step 3: Preliminary hoisting, consolidation pier hoisting and temporary support installation; Step 4: Divide the construction into sections, which are divided into 7 sections vertically and 4 sections horizontally, a total of 28 sections, namely A1-A7, B1-B7, C1-C7, and D1-D7; Step 5: Carry out hoisting construction and complete the hoisting.

2. The steel box girder installation construction method based on folding arm crane hoisting according to claim 1 is characterized in that: In step 1: according to the characteristics of the steel structure and the weight statistics of the segments, combined with the elevation of the steel box beam in the design drawings and the actual ground elevation on site, it is concluded that the height of the steel box beam is 9.5-10.5m, and the maximum weight of the steel box hoisting component is 29.65t. Two 150-ton folding arm cranes are selected for hoisting; 1) Determine the lifting height H required for hoisting: H = height of steel box girder in place + height of sling + safety distance of hook; 2) Determine the length of the boom: According to the principle that the hoisting height of the crane shall not be less than H, taking into account the height of the crane's large hook and the limit height, it was preliminarily determined that the boom length would adopt a five-section boom, the heaviest section of the steel box girder is 29.65t, the swing radius during operation is 13m, the five-section boom, and the lifting capacity is 31×2*75%=46.5>29.65×1.1*1.25=40.77t. Two 150t folding arm cranes meet the requirements.

3. The steel box girder installation construction method based on folding arm crane hoisting according to claim 1 is characterized in that: The specific process of the most unfavorable working condition analysis in step 1 is: The most unfavorable working condition is the lifting of the C6 section of the fifth section of the D ramp. The truck crane is located on the hardened foundation. The lifting beam section weighs 29.65t. During the lifting process, the crane arm collides with the box beam because the distance is close to the set value during the rotation process. To prevent this from happening, the most unfavorable working condition C6 section is analyzed. The crane station is located on the side of the bridge. The swing radius during operation is 13m, with a five-section arm and a lifting capacity of 31×2*75%=46.5>29.65×1.1*1.25=40.77t, which meets the lifting requirements.

4. The steel box girder installation construction method based on folding arm crane hoisting according to claim 1 is characterized in that: The specific process of step 2 is: The heaviest load condition is 300t truck crane lifting 38.68t, 300t crane deadweight 54.99t+100t=154.99t, counterweight 100t, 2.5m*2.5m pads are used. If the foundation bearing capacity of the steel box girder of the largest beam section to be lifted meets the requirements, the rest are met; The contact area between a single crane and the ground is the contact area between two pads, which is 2.5m×2.5m×2=12.5m 2 , the maximum reaction force can be calculated according to the following formula: R max =a×(P+Q)(1.1) Where P is the deadweight of the crane, Q is the lifting weight, and a is the dynamic load coefficient. Calculated as a=1.1, we get: <h2 style=";text-align:left;direction:ltr">R<h2 style=";text-align:left;direction:ltr"> max <h2 style=";text-align:left;direction:ltr"> =1.1×(154.99t+38.68t)×10N / kg=2130.37KN(1.2) The uniformly distributed load on the site during crane lifting is: P=R max / S=2130.37KN / 12.5m 2 =170.43KPa(1.3) The bearing capacity of the foundation is required to be hardened to 250KPa>170.43KPa, which meets the requirements of automobile crane lifting. In order to balance the different settlement problems of foundation and roadbed, a 2.5*2.5m roadbed box is added under the non-roadbed crane legs, which is provided by the crane to reduce the influence of settlement factors.

5. The steel box girder installation construction method based on folding arm crane hoisting according to claim 1 is characterized in that: The specific process of step 3 is: The consolidation pier is hoisted by a 100T crane, with a turning radius of 8m, a boom length of 31m, a lifting capacity of 31.8 tons, and a beam section weight of 2.16×1.1=2.38t<31.8t, which meets the hoisting requirements. Before hoisting, a guy rope is arranged at the diagonal position of the lower part of the consolidation pier to facilitate the hoisting angle control. It needs to be installed in advance, poured and reached the design strength before the subsequent beam section hoisting and temporary support installation. There are 6 sets of temporary supports in the fifth unit of D ramp.

6. The steel box girder installation construction method based on folding arm crane according to claim 1 is characterized in that: The specific process of step 5 is: Step 5.1: The beam sections A7, B7, C7, and D7 are hoisted by a 300-ton truck crane in the order of B7→A7→C7→D7. The crane body is perpendicular to the longitudinal bridge design line, and the rear of the crane faces the bridge position. Four sections are hoisted without moving the crane. The turning radius is 18m, the arm length is 40.3m, and the lifting capacity is 40 tons. The heaviest beam section is 26.9×1.1=29.59t<40t, which meets the hoisting requirements and can be hoisted; Step 5.2: The A6-B6 beam section is first unloaded by two 150-ton folding arm cranes. Before installation, the cantilever arm and the main beam are made into an integral whole using a horse plate. The turning radius is 9-13m, the arm length is five-section arm, the highest is 13 meters, and the lifting capacity is 30 tons. The heaviest beam section is 29.34×1.1=32.27t<30×2×75%=45t, which meets the lifting requirements and can be unloaded. The A6+B6 beam section is hoisted by two 150-ton folding arm cranes. The turning radius is 9-13m, the arm length is five-section arm, the highest is 13 meters, and the lifting capacity is 30 tons. The beam section weight is (29.34+7.44)×1.3=40.46t<30×2×75%=45t, which meets the lifting requirements and can be hoisted; Step 5.3: The C6 and D6 beam sections are hoisted by two 150-ton folding arm cranes, with a slewing radius of 9-13m and a five-section arm length, a maximum of 13 meters, and a lifting capacity of 30 tons. The heaviest beam section is C6: 29.65×1.1=32.62t<30×2×75%=45t, which meets the hoisting requirements and can be hoisted; Step 5.4: The A5-B5 beam section is unloaded by two 150-ton folding arm cranes. Before installation, the cantilever arm and the main beam are made into an integral whole using a horse plate. The turning radius is 9-13m, the arm length is five-section arm, the highest is 13 meters, and the lifting capacity is 30 tons. The heaviest beam section is 27.06×1.1=29.77t<30×2×75%=45t, which meets the lifting requirements and can be unloaded. The A5+B5 beam section is hoisted by two 150-ton folding arm cranes. The turning radius is 9-13m, the arm length is five-section arm, the highest is 13 meters, and the lifting capacity is 30 tons. The beam section weight is (27.06+6.86)×1.1=37.31t<30×2×75%=45t, which meets the lifting requirements and can be hoisted; Step 5.5: The C5 and D5 beam sections are hoisted by two 150-ton folding arm cranes, with a slewing radius of 13m and a five-section arm length, a maximum of 13m, and a lifting capacity of 30 tons. The heaviest beam section is: 27.35×1.1=30.09t<30×2×75%=45t, which meets the hoisting requirements and can be hoisted; Step 5.6: The beam sections A4-D4 and A3-D3 are hoisted by a 300-ton truck crane, with a slewing radius of 14m / 18m, a boom length of 40.3m, and a lifting capacity of 55 / 40 tons. The heaviest beam section is the C3 beam section: 36.59×1.1=40.25t<55t, which meets the hoisting requirements and can be hoisted. The hoisting sequence is B4→A4→C4→D4→B3→A3→C3→D3; Step 5.7: The B2 beam section is hoisted by a 300-ton truck crane, with a slewing radius of 14m, a boom length of 40.3m, a lifting capacity of 55 tons, and a beam section weight of 38.29×1.1=42.12t<55t, which meets the hoisting requirements and can be hoisted; Step 5.8: The A2, C2, D2, and A1-D1 beam sections are hoisted by a 300-ton truck crane. The crane station is located at the exit of the Inner Ring Expressway, and the beam truck is parked on the emergency lane of the Inner Ring Expressway. The turning radius is 14m / 18m, the arm length is 40.3m, and the lifting capacity is 55 / 40 tons. The heaviest beam section is the C2 beam section: 38.68×1.1=42.55t<55t, which meets the hoisting requirements and can be hoisted. The hoisting sequence is C2→D2→A2→B1→C1→D1→A1.

7. The steel box girder installation construction method based on folding arm crane according to claim 1 is characterized in that: In step 5, the specific process of hoisting and adjusting the steel box girder is as follows: Check whether the crane station is safe and whether there are any dangerous sources around. Connect the wire rope to the lifting lug with a snap ring and connect the other end of the wire rope to the main hook. To ensure that the wire rope is not broken, the wire rope hoisting angle should not be less than 60°; Before the official lifting operation, the truck crane should conduct a trial lifting of the steel box girder. Before the trial lifting, the personnel participating in the lifting should strictly check the performance of the lifting lugs, lifting machinery and rigging according to the division of labor. Only after confirming that they meet the requirements of the plan can the trial lifting be carried out. Before lifting, two cable wind ropes are set at both ends of the beam section, and then each rope is controlled by two workers to control the state of the beam section in the air. After the hook and the lifting lug are hung, start to lift slowly to 100mm from the starting position, keep for more than 10 minutes, and confirm whether the center of gravity position of the lifting point meets the box girder balance; if not, adjust the length of the wire rope by adding lifting rings to ensure that the center of gravity of the steel beam is in the center until the box girder maintains a balanced state during the lifting process, and check the stability of the crane, the reliability of the brake, the balance of the steel box girder, and the firmness of the binding. After confirmation, the formal lifting can be carried out; The box girder is hoisted by a truck crane, and the beam section leveling measures are as follows: (1) According to the structural form and weight of the box girder during hoisting, calculate the center of gravity of the beam section and reasonably arrange the lifting lugs at both ends of each box girder section; (2) According to the longitudinal slope of the box girder, the pre-camber value and the on-site lifting conditions, select appropriate lifting wire ropes, shackles, chain hoists and other tools, and determine the length of the wire ropes at both ends of the hook; (3) When the hoisting beam section is close to the working surface, it is connected by a hand chain hoist and the position of the steel box girder is controlled by adjusting the length of the hand chain hoist; (4) During the installation process of the steel box girder, its state needs to be constantly adjusted, and rough and fine adjustments are performed to ensure that the steel box girder is installed smoothly in place; The precise positioning and adjustment of the steel box girder are as follows: (1) Before lifting, two cables are tied to the segment to control the state of the segment in the air. After the segment hooks are hung on the lifting points of the steel box girder top plate, the safety officer will inspect and accept them. After passing the inspection, the lifting commander will command the crane driver to slowly lift the segment. When the predetermined lifting height is reached, it will exceed the top surface of the temporary support by more than 1m. The lifting commander will command the crane to slowly rotate the boom to the top of the predetermined installation position. The crane will slowly drop the hook to lift the segment to 10cm above the top surface of the temporary support and stop. Then, the steel box girder will be initially positioned by manual reference to the edge line and center line of the bottom plate of the steel box girder released in advance, and the crane will continue to slowly drop the hook to the installation position. Line type horizontal and vertical adjustment control: The linear control of the steel box girder should first be carried out in the factory. Before hoisting, control points and lines are set on the permanent piers and temporary piers, and control points and lines are set accordingly on the steel box girder. When the steel box girder is installed, the center line and longitudinal distance are controlled by the control points and lines set on the piers in advance corresponding to the points and lines set on the steel box girder. At the same time, the measurement instrument is used for synchronous monitoring. The elevation of the steel box girder is calculated by setting out and directly reflected in the height of the adjustment pipe. After the center line, longitudinal distance and beam elevation are adjusted, welding can be carried out at the joints of each section of the box body to ensure the smooth linear shape of the steel box girder. During the deepening of the steel box girder drawings, the construction pre-arch is added to the original design pre-arch, and the temporary support elevation is in line with the actual beam bottom line shape. After the on-site installation is completed and the support is removed, the design pre-arch value is reached under the action of gravity; Temporary measures for steel box girder placement: After the steel box girder is temporarily in place, the bottom plate of the steel box girder and the contact surface of the temporary support are fully welded to prevent the steel box girder from slipping and overturning. The in-place beam section is temporarily fixed with a horse plate at the interface of the steel box girder section to prevent the displacement of the steel box girder section. After the hoisting and welding are completed, the temporary fixing measures will be removed.

8. The steel box girder installation construction method based on folding arm crane hoisting according to claim 1 is characterized in that: During the suspension installation of the steel box girder in step 5, there are suspension working conditions during the hoisting of the third section of the D ramp and the ninth section of the main line, and during the hoisting of the cantilever structure; when using a truck crane to hoist the suspended beam section, after the steel box girder is in place, use an aerial work vehicle to weld the horse plate at the joint to position it, and assemble the horse plate arrangement. At the same time, use 40b I-beams to strengthen the top and bottom plates, with two top and bottom plates. After the above work is completed, the truck crane can unload the loose hook. After all the ring welds are completed, use an aerial work vehicle to remove the horse plate and grind and repair the welds; The saddle plate should be made of a rectangular steel plate of 200mm×100mm×10mm, and arranged one every 300mm along the segment interface direction. The welding foot of the saddle plate and the component should not be less than 6mm.

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