A construction control method for a single-leaning-tower cable-stayed bridge

Abstract

The present invention provides a construction control method for a single-leaning tower cable-stayed bridge, which adopts multiple control means of supporting active jacking force, cable tensioning force and main beam counterweight during the construction process. Based on the finite element model, the maximum stress safety margin during the structural construction process is taken as the principle, and the complexity of the construction is reduced, so as to obtain the optimal jacking force, cable tensioning force and main beam counterweight scheme. The construction control method has the following steps: establishing a finite element model of the refined construction process of the whole bridge, and accurately simulating the influence of the supporting jacking force, cable tensioning force and main beam counterweight on the structural construction stress in the model; obtaining the optimal combination of the optimal jacking force, cable tensioning force and main beam counterweight through sensitivity analysis in the model. The beneficial effects of the present invention are: reducing the difficulty of the inclined tower construction, combining the finite element method with multiple control means to more accurately control the stress and line shape of the inclined tower during the construction process, and ensuring the safety of the structural construction process.

Description

Technical Field

[0001] The invention belongs to the technical field of construction, and in particular relates to a construction control method for a single-leaning-tower cable-stayed bridge. Background Art

[0002] The cable-stayed bridge is a highly hyperstatic composite system bridge, and its superstructure consists of three parts: the main beam, the cable-stayed cable, and the bridge tower. Unlike other system bridges, the cable-stayed bridge can change the stress state and line shape of the main beam and the main tower by adjusting the cable force. People are pursuing higher and higher for the appearance of bridges, and bridges with an artistic sense are more recognized and favored by people. Bridge engineers have designed a single-tilted tower cable-stayed bridge, which not only inherits the characteristics of the ordinary cable-stayed bridge with a light bridge body and smooth lines, but also the inclined tower brings an asymmetrical beauty and a strong visual impact. But at the same time, the tilt of the bridge tower has caused great difficulties in the construction process of the cable-stayed bridge, and the construction of such bridges is becoming more and more difficult.

[0003] Compared with the double-tower or multi-tower cable-stayed bridge, the single-tower cable-stayed bridge has a much smaller span. This relatively novel structural system is a breakthrough in the structural system compared to the conventional straight-tower cable-stayed bridge. The cable tower of the inclined tower system is the key component of the entire structural system. Its design concept is essentially to use the deadweight of the inclined cable tower to replace the role of some side span cables. At present, the construction of the inclined tower can adopt the self-balancing construction method, that is, the method of relying on the strength of the inclined tower to bear various loads during the construction process. At the same time, the super-high steel pipe scaffolding is only used as a construction platform and does not bear the deadweight of the inclined tower. However, this method requires the bridge tower itself to have a high bearing capacity and the cost of the bridge tower is relatively high. In addition, the construction of the inclined tower can also adopt the installation of a temporary support structure on the inclined side of the inclined tower to resist the overturning moment generated by the gravity of the inclined tower at the root of the bridge tower. The temporary support plays a restraining role on the deformation of the inclined tower, generates a restraining force on the inclined tower, and passively eliminates the adverse bending moment generated by the subsequent construction on the inclined tower. This method cannot completely eliminate the adverse effects of the construction before the temporary support is set up. After the temporary support is removed in the bridge completion stage, there is still residual stress at the root of the bridge tower. At the same time, as the tower construction sections continue to rise, the deadweight load continues to increase, and the support force provided by passive temporary supports is often insufficient. Therefore, it is often necessary to set up many temporary supports to ensure the stress safety of the bridge tower. This not only increases the amount of steel used, but also requires more manpower and working hours. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of difficulty in construction of the inclined tower and difficulty in controlling the stress and linearity of the inclined tower in the existing single-inclined-tower cable-stayed bridge construction. A construction control method using multiple control means of supporting active jacking force, cable tension and main beam counterweight is proposed, including the following steps:

[0005] Step 1, establish finite element model: according to the information of the planned single-tilted tower cable-stayed bridge, use Midas / Civil finite element analysis software to establish a detailed construction process model of the whole bridge; the main beam, main pier and bridge tower are simulated by spatial beam units, and the cable-stayed cable is simulated by tension-only truss units; the upper support of the back support of the bridge tower is elastically connected to the bridge tower through a steel arm, and the lower support of the support is consolidated with the ground; the active thrust of the support is added by a jack, and the jack is simulated by a truss unit; the main beam counterweight is added by uniformly distributing loads;

[0006] Step 2: Determine the optimal jacking force scheme: Use the model to conduct a sensitivity analysis of the active jacking force, mainly including the jacking force height position, jacking force angle and jacking force size;

[0007] Step 21, changing the active jacking force height of the support, keeping other parameters unchanged, and studying the variation law of the maximum stress during the construction stage of the bridge tower under different jacking force heights;

[0008] Step 22, changing the active jacking force angle of the support, the angle is controlled by the tripod, keeping other parameters unchanged, and studying the variation law of the maximum stress during the construction stage of the bridge tower under different jacking force angles;

[0009] Step 23, changing the magnitude of the active jacking force of the support, keeping other parameters unchanged, and studying the variation law of the maximum stress during the construction stage of the bridge tower under different jacking force magnitudes;

[0010] Step 24, determining the optimal jacking force scheme according to the rules of step 21 to step 23 so as to maximize the stress safety margin during the bridge tower construction stage;

[0011] Step 3, determine the optimal cable tension: in the established full-bridge finite element model, by controlling the stress and displacement of the key sections of the bridge tower and the main beam during the construction process, changing the cable tension, keeping other parameters unchanged, and studying the stress variation law of the bridge tower and the main beam during the construction stage under different cable tensions, so as to determine the optimal cable tension to maximize the stress safety margin of the bridge tower and the main beam during the construction stage;

[0012] Step 4, determine the optimal main beam counterweight scheme: perform main beam counterweight sensitivity analysis through the model, the counterweight is added to the steel main beam segment, the counterweight is added through uniformly distributed load, mainly including the counterweight position and counterweight size; change the position of the steel main beam segment where the counterweight is added in the model, keep the counterweight size unchanged, and study the stress change law of the bridge tower and main beam construction stage under different counterweight addition positions, so as to determine the optimal counterweight position so that the stress safety margin of the bridge tower and main beam construction stage is maximized; the method for determining the optimal counterweight size is the same as above.

[0013] The beneficial effects of the construction control method of a single-leaning tower cable-stayed bridge of the present invention are as follows: an optimization model based on the risk control of the construction process of the single-leaning tower cable-stayed bridge is established, and a construction control method using multiple control means of supporting active jacking force, cable tension and main beam counterweight is proposed. Based on the principle of maximizing the stress safety margin of the structure during the construction process, and considering reducing the complexity of the construction, the optimal supporting active jacking force, cable tension and main beam counterweight scheme are obtained through parameter analysis and optimization design methods, thereby ensuring the safety of the bridge tower during the construction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a facade layout diagram of a single-leaning-tower cable-stayed bridge used as an example in the construction control method of the invention.

[0015] Figure 2 for Figure 1 Schematic diagram of the full-bridge finite element model.

[0016] Figure 3 for Figure 2 Back support diagram of the middle bridge tower.

[0017] Figure 4 for Figure 3 Schematic diagram of active thrust application of the mid-back support.

[0018] Figure 5 for Figure 3 Schematic diagram of the tripod with center back support.

[0019] Figure 6 for Figure 2 Schematic diagram of adding counterweight to the middle main beam.

[0020] Figure 7 for Figure 1 Construction section division diagram of the middle bridge tower.

[0021] Figure 8 for Figure 1 Schematic diagram of the construction of the middle bridge tower foundation.

[0022] Fig. 9 for Figure 1 Schematic diagram of the construction of the lower tower column of the middle bridge tower.

[0023] Fig.10 for Figure 1 Schematic diagram of the construction of the middle tower-beam joint section.

[0024] Fig.11 for Figure 1 Schematic diagram of the construction of the middle tower column of the middle bridge tower.

[0025] Fig.12 for Figure 3 Schematic diagram of the construction of the back support of the first bridge tower.

[0026] Fig.13 for Figure 3 Schematic diagram of the construction of the back support of the second bridge tower.

[0027] Fig.14 for Figure 3 Schematic diagram of the back support construction of the third bridge tower.

[0028] Fig.15 for Figure 1 Schematic diagram of the construction of the upper tower column of the middle bridge tower.

[0029] Fig.16 for Figure 1 Schematic diagram of the tensioning of 1-11# cable-stayed cables.

[0030] Fig.17 for Figure 1 Schematic diagram of the removal of bridge tower supports.

[0031] Fig.18 for Figure 1 Schematic diagram of the tensioning of No. 12-17 cable stays.

[0032] Fig.19 for Figure 1 Schematic diagram of the middle full bridge closure. DETAILED DESCRIPTION

[0033] The single-leaning tower construction control method of the present invention adopts multiple control means of supporting active jacking force, cable tension and main beam counterweight. The method is further described in detail in conjunction with the accompanying drawings, and is specifically applied to the construction example of a single-leaning tower cable-stayed bridge, including the following steps:

[0034] Step 1. Establish a finite element model of the entire bridge: Based on the information of the proposed single-tower inclined tower cable-stayed bridge, the Midas / Civil finite element analysis software is used to establish a detailed construction process model of the entire bridge. The main beam, main pier and bridge tower are simulated using spatial beam units, and the cable-stayed cable is simulated using tension-only truss units. The back support of the bridge tower is made of steel pipe material, the upper support of the back support is elastically connected to the bridge tower through a steel arm, and the lower support of the support is consolidated with the ground. The active thrust of the support is added through a jack, and the jack is simulated using a truss unit. The main beam counterweight is added by uniformly distributing the load.

[0035] Step 2, determine the optimal support active jacking force scheme: The sensitivity analysis of the support active jacking force is carried out through the established full-bridge finite element model, mainly including the jacking force height position, jacking force angle and jacking force size. (1) Change the support active jacking force height, keep other parameters unchanged, and study the change law of the maximum stress in the bridge tower construction stage under different jacking force heights. (2) Change the support active jacking force angle, the angle is controlled by the tripod, keep other parameters unchanged, and study the change law of the maximum stress in the bridge tower construction stage under different jacking force angles. (3) Change the support active jacking force size, keep other parameters unchanged, and study the change law of the maximum stress in the bridge tower construction stage under different jacking force sizes. According to the above-obtained law of the change of bridge tower stress with jacking force parameters, determine the optimal jacking force scheme to maximize the stress safety margin in the bridge tower construction stage.

[0036] Step 3, determine the optimal cable tension: In the established finite element model of the whole bridge, by controlling the stress and displacement of the key sections of the bridge towers and main beams during the construction process, continuously changing the cable tensioning force, keeping other parameters unchanged, and studying the stress variation law of the bridge towers and main beams under different cable tensions during the construction stage, so as to determine the optimal cable tension to maximize the stress safety margin of the bridge towers and main beams during the construction stage.

[0037] Step 4, determine the optimal main beam counterweight solution: The main beam counterweight sensitivity analysis is performed through the established full-bridge finite element model. The counterweight is added to the steel main beam segment, mainly including the counterweight position and counterweight size. Change the position of the steel main beam segment where the counterweight is added in the model, keep the counterweight size unchanged, and study the stress change law of the bridge tower and main beam construction stage under different counterweight addition positions, so as to determine the optimal counterweight position so that the stress safety margin of the bridge tower and main beam construction stage is maximized. The method for determining the optimal counterweight size is the same as above. In this example, the optimal counterweight positions are obtained for the 3#, 7# and 11# steel main beam segments, and the counterweight size is 100kN / m.

[0038] Step 5, determine the optimal time to remove the support: change the time to remove the back support of the bridge tower in the model, keep other model parameters unchanged, and study the stress changes during the construction stage of the bridge tower under different support removal times, so as to determine the optimal time to remove the support so that the stress safety margin during the construction stage of the bridge tower is the largest. In this model, the optimal time to remove the support is after the 11# cable is tensioned.

[0039] Step 6: Construct bridge tower foundation: During the tower foundation construction process, set up the tower column construction platform and install the tower crane.

[0040] Step 7: Construction of lower tower column: set up construction support, tie up the steel bars of lower tower column, and set up formwork to pour concrete of lower tower column up to 4 sections.

[0041] Step 8, tower-beam joint section construction: set up the full-height bracket of the main beam of the tower-beam joint section, pre-stress the full-height bracket to eliminate inelastic deformation. Tie the steel bars of the tower-beam joint section, and cast the concrete of the 5 sections of the tower column (tower-beam joint section) in a mold and cure. When the concrete strength of the main beam reaches 90% of the design strength grade value and the concrete age is not less than 7 days, tension the transverse prestressing of the beam at the consolidation of the tower beam, the web plate, and the top plate steel bundles and anchor them, and vacuum-assisted grouting.

[0042] Step 9, construction of the middle tower column: tie the middle tower column steel bars, set up the formwork to cast the middle tower column concrete, and cure it. Lift the formwork to cast the middle tower column to the 8th section, and set up temporary horizontal supports at the corresponding positions.

[0043] Step 10, construct the first support: tie the steel bars of the middle tower column. Set up the formwork to cast the middle tower column concrete and cure it. Lift the formwork to cast the middle tower column to a position about 25m above the bridge deck, and set up temporary horizontal supports at the corresponding positions. Lift the formwork to cast the middle tower column to the 10th section, and set up temporary vertical diagonal braces made of steel tube concrete at a position of 19.5m on the bridge deck. Apply the first support active jacking force, adding it according to the optimal active jacking force size, angle and jacking position obtained in step 2.

[0044] Step 11, construct the second support: tie the steel bars of the middle tower column, set up the formwork to cast the middle tower column concrete, and cure it. Lift the formwork to cast the middle tower column to a position about 36m above the bridge deck, and set up temporary horizontal supports at the corresponding positions. Lift the formwork to cast the middle tower column to the 12th segment, and set up temporary vertical diagonal braces made of steel tube concrete at the corresponding appropriate positions. Apply the second support active jacking force, adding it according to the optimal active jacking force size, angle, and jacking position obtained in step 2.

[0045] Step 12, construct the third support: tie the steel bars of the middle tower column, set up the formwork to cast the middle tower column concrete, and cure it. Lift the formwork to cast the middle tower column to the 17-2 section at the top of the middle tower column, and set up temporary horizontal supports at the corresponding positions. Lift the formwork to cast the middle tower column to the 12th section, and set up temporary vertical diagonal braces of steel tube concrete at the corresponding appropriate positions. Apply the second support active jacking force, and add it according to the optimal active jacking force size, angle, and jacking height position obtained in step 2.

[0046] Step 13: Construction of the upper tower column: Tie up the upper tower column reinforcement, set up the formwork to pour the upper tower column concrete in sections, and cure it. After the upper tower column is constructed to the 22nd section, remove the temporary lateral support of the middle tower column.

[0047] Step 14, tensioning 1-11# cable stays: hoist steel box segment 1#, install and tension 1# cable stays for the first time; move the bridge crane forward to position, tension 1# cable stays for the second time until the cable force is in place. Hoist 1-11# steel box segments, tension 1-11# cable stays for the first time and tension 1-11# cable stays for the second time in the above order. After tensioning the cables, carry out the main beam counterweight according to the steps, and add the counterweight position to 3#, 7# and 11# steel main beam segments.

[0048] Step 15: Dismantle the back supports of the bridge tower: dismantle them in sequence according to the construction sequence of the back supports of the bridge tower, and ensure that the bridge tower is in a stress-safe state during the process.

[0049] Step 16, tensioning 12-17# cable stays: hoist steel box segment 12#, install and tension 12# cable stays for the first time; move the bridge crane forward to position, tension 12# cable stays for the second time until the cable force is in place. Hoist 12-17# steel box segments, tension 12-17# cable stays for the first time and tension 12-17# cable stays for the second time in the above order.

[0050] Step 17: Closing of the whole bridge: hoisting of steel box segment 18#, closing of the whole bridge. Dismantling of the bridge crane, installing two decorative pipes of the middle tower column, and dismantling of the tower crane.

[0051] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A construction control method for a single-leaning-tower cable-stayed bridge, characterized in that: The steps include: Step 1: Establish a finite element model; Step 2: Determine the optimal thrust force solution; Step 3, determining the optimal cable tension; Step 4: Determine the optimal main beam counterweight solution; Step 1 is to establish a detailed construction process model of the whole bridge using Midas / Civil finite element analysis software based on the information of the planned single-tilted-tower cable-stayed bridge; the main beam, main pier and bridge tower are simulated using spatial beam units, and the cable-stayed cable is simulated using tension-only truss units; the upper support point of the back support of the bridge tower is elastically connected to the bridge tower through a steel arm, and the lower support point of the support is consolidated with the ground; The active jacking force of the support is added by the jack, which is simulated by the truss unit; the main beam counterweight is added by uniformly distributing the load; Step 2 includes: Step 21, changing the height of the active jacking force of the support, keeping other parameters unchanged, and studying the variation law of the maximum stress during the construction stage of the bridge tower under different jacking force heights; Step 22, changing the active jacking force angle of the support, the angle is controlled by the tripod, keeping other parameters unchanged, and studying the variation law of the maximum stress during the construction stage of the bridge tower under different jacking force angles; Step 23, changing the magnitude of the active jacking force of the support, keeping other parameters unchanged, and studying the variation law of the maximum stress during the construction stage of the bridge tower under different jacking force magnitudes; Step 24, determining the optimal jacking force scheme according to the rules of step 21 to step 23 so as to maximize the stress safety margin during the bridge tower construction stage; Step 3 is to control the stress and displacement of the key sections of the bridge tower and the main beam during the construction process in the established finite element model of the whole bridge, change the tension of the cable, keep other parameters unchanged, and study the stress variation law of the bridge tower and the main beam during the construction stage under different cable tensions, so as to determine the optimal cable tension to maximize the stress safety margin of the bridge tower and the main beam during the construction stage; Step 4 is to conduct a sensitivity analysis of the main beam counterweight through the model. The counterweight is added to the steel main beam segment. The counterweight is added through a uniformly distributed load, which mainly includes the counterweight position and counterweight size. The position of the steel main beam segment where the counterweight is added in the model is changed, and the counterweight size is kept unchanged. The stress change law of the bridge tower and the main beam during the construction stage under different counterweight addition positions is studied to determine the optimal counterweight position so that the stress safety margin of the bridge tower and the main beam during the construction stage is maximized. The method for determining the optimal counterweight size is the same as above.

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