Fabricated preloading throwing and supporting system and construction method thereof

Abstract

The invention discloses an assembly type preloading throwing support system and a construction method thereof, and the system comprises an assembly type counter-force frame which is close to a foundation pit support structure and is vertically arranged on a structural floor slab of an underground two-layer main body structure below a first inner support; and the loading device is close to the first inner support and is horizontally arranged between the fabricated reaction frame and the foundation pit support structure. According to the method, active deformation control can be conducted on the foundation pit enclosure structure, the displacement and instability risks of the foundation pit and the enclosure structure of the foundation pit are reduced, and the construction safety of the surrounding environment of the foundation pit and an underground structure is guaranteed. The device has the advantages of being convenient to disassemble and assemble, efficient, safe, economical and energy-saving.

Description

Technical Field

[0001] The present invention relates to the technical field of building construction, and in particular to an assembled preloaded towing system and a construction method thereof. Background Art

[0002] During the construction of underground structures, after the first internal support is removed, a cantilever section is formed on the top of the foundation pit. This cantilever section loses effective support and can only rely on itself to resist the soil pressure of the foundation pit, which poses a great safety hazard. The existence of the cantilever section increases the horizontal displacement and deformation of the retaining structure, causing adverse effects on the surrounding environment and underground facilities of the foundation pit. In order to reduce the impact of the cantilever section on the retaining structure, before the first internal support is removed, concrete diagonal braces and steel pipe diagonal braces are traditionally used to temporarily support the retaining structure. However, these traditional support methods have significant disadvantages: the construction process of concrete diagonal braces is complicated, requiring formwork and pouring, resulting in cumbersome construction site operations, long time consumption and low efficiency; steel pipe diagonal braces are difficult to install and inefficient due to their heavy weight and the installation and removal process consumes a lot of manpower and machinery, especially in narrow construction spaces. At the same time, these traditional support forms are usually passive supports, which cannot actively and effectively control the deformation of the retaining structure and cannot fully eliminate the potential risks caused by the formation of cantilever sections. Summary of the invention

[0003] The purpose of the present invention is to provide an assembled preloaded bracing system and a construction method thereof, so as to solve the problems that before the first inner support is removed, the conventional use of concrete inclined bracing and steel pipe inclined bracing to passively support the cantilever section of the foundation pit retaining structure cannot effectively control the deformation of the foundation pit retaining structure and the foundation pit, and the conventional inclined bracing has a long installation period and is inconvenient to install and disassemble.

[0004] In order to solve the above technical problems, the present invention provides an assembled preloaded guying system, including an assembled reaction frame vertically installed on the structural floor of the second underground main structure below the first internal support close to the foundation pit retaining structure, and a loading device horizontally arranged between the assembled reaction frame and the foundation pit retaining structure close to the first internal support.

[0005] Furthermore, the present invention provides an assembled preloaded towing system, wherein the loading device includes a jack and a force transmission rod adjustably connected thereto via a flexible head.

[0006] Furthermore, the present invention provides an assembled preloaded guy support system, wherein the assembled reaction frame includes at least one standard section frame body detachably connected to the structural floor of the second underground main structure below the first inner support through embedded parts and a reaction support frame detachably connected thereto.

[0007] Furthermore, in the assembled preloaded catapult system provided by the present invention, the upper end of the counter-support frame is a step surface, and the loading device is horizontally arranged between the step surface and the foundation pit retaining structure.

[0008] Furthermore, in the assembled preloaded catapult system provided by the present invention, the loading device is arranged on the foundation pit retaining structure through a temporary purlin horizontally arranged between the upper end surface of the outer wall of the first underground floor and the foundation pit retaining structure.

[0009] Furthermore, in the assembled preloaded catapult system provided by the present invention, the jack of the loading device is arranged on the step surface of the anti-support frame, and the force transmission rod of the loading device is connected to the temporary purlin through the embedded steel plate placed on the temporary purlin.

[0010] Furthermore, in the assembled preloaded catapult system provided by the present invention, the end face of the jack is arranged on the step surface of the step surface through the end steel plate and multiple groups of force transmission beams between the end steel plate and the step surface between the low-order horizontal surface and the high-order horizontal surface of the step surface.

[0011] Furthermore, in the assembled preloaded catapult system provided by the present invention, the jack is installed on the lower level surface of the step surface through a pad.

[0012] In order to solve the above technical problems, the present invention also provides a construction method of an assembled preloaded towing system, comprising:

[0013] After the construction of the main structure of the underground second floor is completed, multiple assembled reaction frames are vertically installed on the structural floor slab of the main structure of the underground second floor below the first inner support close to the foundation pit retaining structure;

[0014] A loading device is horizontally arranged between each of the assembled reaction frames and the foundation pit retaining structure near the first inner support to form a plurality of assembled preloaded towing support systems;

[0015] Before the first inner support is removed, a jacking force is applied to the foundation pit retaining structure through each loading device, so that after the first inner support is removed, the foundation pit retaining structure on the side is supported by each assembled preloaded support system.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The assembled preloaded shoring system and the construction method thereof provided by the present invention are as follows: when the underground structure construction completes the underground second-floor main structure, a plurality of assembled preloaded shoring systems are installed; before the first inner support is removed, a preload force is applied to the foundation pit retaining structure by each loading device of each assembled preloaded shoring system; before the first inner support is removed, the foundation pit retaining structure is pushed in advance; the force of the foundation pit retaining structure is transmitted to the underground second-floor main structure via the assembled reaction frame reaction force by the loading device, so as to form a stable reaction force support system, and realize the balanced transmission of the preloaded shoring force and the reaction force, so as to actively control the foundation pit retaining structure by each assembled preloaded shoring system; after the first inner support is removed, the foundation pit retaining structure is supported by each assembled preloaded shoring system on the cantilever section formed by the foundation pit retaining structure, and the value of the preload force is adjusted according to the foundation pit situation, so as to actively control the deformation of the foundation pit retaining structure, reduce the displacement and instability risks of the foundation pit and its retaining structure, and ensure the construction safety of the surrounding environment of the foundation pit and the underground structure.

[0018] The prefabricated preloaded shoring system and the construction method thereof provided by the present invention are composed of a loading device and a prefabricated reaction frame, and have the advantages of simple structure, convenient installation and disassembly, can reduce the occupation of on-site space, can be recycled and reused, and have the advantages of high efficiency, safety, economy and energy saving. Compared with concrete inclined shoring and steel pipe inclined shoring, it has a short construction period, simple construction process, high efficiency, and avoids the time-consuming and labor-intensive problem of using engineering machinery to transport steel pipes and their disassembly and assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a planar structural diagram of installing an assembled preloaded catapult system on the main structure of the second underground floor;

[0020] Figure 2 It is a schematic diagram of the elevation structure of the assembled preloaded catapult system installed on the main structure of the second underground floor;

[0021] Figure 3 It is a schematic diagram of the elevation structure of the dismantling of the assembled preloaded catapult system and the construction of the main structure of the underground floor;

[0022] Figure 4 It is a structural diagram of the anti-support frame;

[0023] Figure 5 It is an enlarged view of the loading device installation node;

[0024] As shown in the figure:

[0025] 1. Foundation pit retaining structure, 2. Enclosure purlin, 3. First internal support, 4. Main structure of the second underground floor, 5. External wall of the first underground floor, 6. Temporary enclosure purlin, 7. Pre-buried steel plate, 8. Main structure of the first underground floor;

[0026] 100. Assembled preloaded towing system;

[0027] 110. assembled reaction frame, 111. embedded parts, 112. standard section frame, 113. counter support frame, 114. step surface, 114a. low-step horizontal surface, 114b. step vertical surface, 114c. high-step horizontal surface, 115. flange, 116. high-strength bolts, 117. pad;

[0028] 120. Loading device, 121. Jack, 122. Active head, 123. Force transmission rod, 124. End steel plate, 125. Force transmission beam. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with the accompanying drawings: The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in very simplified form and in non-precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0030] Please refer to Figure 1 to Figure 2 An embodiment of the present invention provides an assembled preloaded support system 100, including an assembled reaction frame 110 vertically installed on the structural floor of the underground second-story main structure 4 below the first internal support 3 near the foundation pit retaining structure 1, and a loading device 120 horizontally arranged between the assembled reaction frame 110 and the foundation pit retaining structure 1 near the first internal support 3.

[0031] Please refer to Figures 1 to 3 The embodiment of the present invention further provides a construction method of an assembled preloaded towing system 100, comprising:

[0032] Step 201 , after the construction of the underground second-floor main structure 4 is completed, a plurality of assembled reaction frames 110 are vertically installed on the structural floor slab of the underground second-floor main structure 4 below the first inner support 3 close to the foundation pit retaining structure 1 .

[0033] Step 202 , a loading device 120 is horizontally arranged between each of the assembled reaction frames 110 and the foundation pit retaining structure 1 close to the first inner support 3 to form a plurality of assembled preloaded support systems 100 .

[0034] Step 203, before the first inner support 3 is removed, each loading device 120 applies a jacking force to the foundation pit retaining structure 1, so that after the first inner support 3 is removed, each assembled preloaded support system 100 supports the foundation pit retaining structure 1 on the side.

[0035] The assembled preloaded shoring system 100 and the construction method thereof provided by the embodiment of the present invention are as follows: when the underground structure construction completes the underground second-floor main structure 4, multiple assembled preloaded shoring systems 100 are installed; before the first inner support 3 is removed, the preload force is applied to the foundation pit retaining structure 1 by each loading device 120 of each assembled preloaded shoring system 100; before the first inner support is removed, the foundation pit retaining structure 1 is pushed in advance; and the force of the foundation pit retaining structure 1 is transmitted to the underground second-floor main structure 4 through the assembled reaction frame 110 by the loading device 120, so as to form a A stable reaction force support system is formed, and the balanced transmission of the preloaded thrust and reaction force is achieved, so that the foundation pit retaining structure 1 is actively controlled through each assembled preloaded support system 100; after the first internal support 3 is removed, the foundation pit retaining structure 1 is supported by each assembled preloaded support system 100 to form a cantilever section of the foundation pit retaining structure 1, and the value of the preload force is adjusted according to the foundation pit conditions to actively control the deformation of the foundation pit retaining structure 1, reduce the displacement and instability risks of the foundation pit and its retaining structure, and ensure the construction safety of the surrounding environment of the foundation pit and the underground structure.

[0036] The assembled preloaded shoring system provided in the embodiment of the present invention forms a complete preload and reaction force system, which can effectively actively support the foundation pit retaining structure 1. The force applied by the loading device 120 is stably transmitted to the underground main structure below it through the assembled reaction frame 110, thereby ensuring that the deformation of the foundation pit retaining structure 1 is effectively controlled. When the underground structure has only one layer, the underground second-layer main structure 4 is the bottom plate.

[0037] The assembled preloaded shoring system 100 and the construction method thereof provided in the embodiment of the present invention are composed of a loading device 120 and an assembled reaction frame 110, and have the advantages of simple structure, convenient installation and disassembly, can reduce the occupation of on-site space, can be recycled and reused, and have the advantages of high efficiency, safety, economy and energy saving. Compared with concrete diagonal shoring and steel pipe diagonal shoring, it has a short construction period, simple construction process, high efficiency, and avoids the time-consuming and labor-intensive problem of using engineering machinery to transport steel pipes and their disassembly and assembly.

[0038] Please refer to Figure 1 to Figure 2In order to ensure the integrity of the loading device 120, the embodiment of the present invention provides an assembled preloaded shoring system 100, wherein the loading device 120 includes a jack 121 and a force transmission rod 123 that is adjustably connected to the jack 121 through an active head 122. The force transmission rod 123 can be a steel pipe or an axle rod, and the active head 122 can be a screw, one end of the screw is connected to the top rod of the jack 121, and the other end of the screw is threadedly connected to the force transmission rod 123. While the force transmission rod 121 is formed into an integral whole by the active head 122, the length of the loading device 120 can be fine-tuned, so that the loading device 120 is reliably connected between the assembled reaction frame 110 and the foundation pit retaining structure 1 to avoid gaps. It also avoids the problem of detachment when the loading device 120 is loaded with preload force, ensuring the tightening effect.

[0039] Please refer to Figure 1 to Figure 2 In order to adapt to the construction of underground structures at different depths of foundation pits, an embodiment of the present invention provides an assembled preloaded support system 100, wherein the assembled reaction frame 110 includes at least one standard section frame body 112 detachably connected to the structural floor of the underground second-story main structure 4 below the first inner support 3 through embedded parts 111, and a removable support frame 113 connected thereto. By combining the standard section frame body 112 and the removable support frame 113, assembled reaction frames 110 of different heights are assembled to adapt to the construction and installation requirements of foundation pits of different depths. The removable support frame 113 is used to provide reaction support for the loading device 120, and the embedded parts 111 enable the standard section frame body 112 to be reliably connected to the structural floor of the underground second-story main structure 4. Alternatively, the embedded parts 111 can be replaced by post-embedded parts. In order to ensure the reliability of the connection of the assembled reaction frame 110, flanges 115 are provided at the connection between the standard section frame body 112 and the counter-support frame 113, and the two are detachably connected by a plurality of high-strength bolts 116 penetrating their respective flanges 115, wherein flanges 115 are also provided at the connection between the standard section frame body 112 and the embedded part 111, and the standard section frame body 112 and the embedded part 111 are also detachably connected by a plurality of high-strength bolts 116 penetrating the flange 115 and the embedded part 111. That is, the assembled reaction frame 110 is mainly composed of the standard section frame body 112 and the counter-support frame 113, and the assembled reaction frame 110 is the main structure for bearing and transmitting the preload force in the whole system, which ensures that the preloaded thrust force can be stably transmitted to the bottom of the foundation pit or the underground main structure, forming a stable reaction force support system. The high-strength bolts 116 realize the detachable connection between the standard section frame body 112 and the embedded parts 111 and the counter-support frame 113, which facilitates the installation and disassembly of the assembled reaction frame 110 and improves the construction efficiency of the system.

[0040] Please refer to Figure 2 , Figures 4 to 5In order to improve the reaction force support effect of the loading device 120, the assembled preloaded support system 100 provided by the embodiment of the present invention has the upper end of the anti-support frame 113 as a step surface 114, and the loading device 120 is horizontally arranged between the step surface 114 and the foundation pit retaining structure 1. The step surface 114 includes a low-order horizontal surface 114a, a high-order horizontal surface 114c, and a step vertical surface 114b located between the low-order horizontal surface 114a and the high-order horizontal surface 114c. At this time, the jack 121 of the loading device 120 is arranged on the step surface 114 of the anti-support frame 113, specifically: the end face of the jack 121 is arranged on the step vertical surface 114b of the step surface 114, and the lower surface of the jack 121 is placed on the low-order horizontal surface 114a of the step surface 114. In order to ensure the stability of the jack 121 on the anti-support frame 113, the jack 121 is installed on the low-level horizontal surface 114a of the step surface 114 through a pad 117, and the pad 117 provides a stable support surface for the jack 121. In order to ensure strength, the pad 117 can be a steel plate. Then, after the jack 121 applies the preload force, it is limited in the step surface 114 and is supported by the reaction force of the step vertical surface 114b of the step surface 114 and transmitted to the anti-support frame 113, and then constructed to the main structure 4 of the underground second floor through the standard section frame body 4, so as to achieve the reaction force support effect. In order to improve the uniformity and reliability of force transmission, the end face of the jack 121 can be set on the step vertical surface 114b of the step surface 114 through the end steel plate 124 and the step vertical surface 114b between the low-level horizontal surface 114a and the high-level horizontal surface 114c of the step surface 114 through multiple groups of force transmission beams 125 between the end steel plate 124 and the step vertical surface 114b between the low-level horizontal surface 114a and the high-level horizontal surface 114c of the step surface 114. The anti-support frame 113 includes but is not limited to an A-frame, which is a triangular design, so that it has good stability and force-bearing capacity, and can effectively withstand the reaction force from the force-transmitting crossbeam 125. The force-transmitting crossbeam 125 is an important component for transmitting the thrust force applied by the jack 121 to the anti-support frame 113. It is installed on the top of the anti-support frame 113 to ensure that the reaction force of the jack 121 can be effectively transmitted to the anti-support frame 113 and finally transmitted to the main structure below it.

[0041] Please refer to Figure 2 In order to avoid damage to the foundation pit retaining structure 1 caused by stress concentration applied by the loading device 120, the assembled preloaded support system 100 provided in the embodiment of the present invention, the loading device 120 is arranged on the foundation pit retaining structure 1 through a temporary purlin 6 horizontally arranged between the upper end surface of the outer wall of the first underground floor and the foundation pit retaining structure 1.

[0042] Please refer to Figure 2In order to improve the reliability of the connection between the loading device 120 and the temporary purlin 6, the assembled preloading towing system 100 provided in the embodiment of the present invention has the force transmission rod 123 of the loading device 120 connected to the temporary purlin 6 through the embedded steel plate 7 placed on the temporary purlin 6. The embedded steel plate 7 can effectively increase the force bearing area, reduce the concentration of local pressure, and make the jacking force of the jack 8 more evenly applied to the foundation pit retaining structure 1 through the temporary purlin 6, avoiding damage to the temporary purlin 6.

[0043] Please refer to Figures 2 to 3 The process of using the assembled preloaded shoring system and the construction method thereof provided by the embodiment of the present invention to construct an underground structure can be as follows:

[0044] Step 301, during the construction of the underground second floor main structure 4, the embedded parts 111 are placed in the structural floor of the underground second floor main structure 4. The embedded parts 111 need to be installed parallel to the ground, and ensure that the upper high wall bolts 116 and the standard section frame 112 can be tightly connected. During the installation process, the position accuracy of the embedded parts 111 needs to be ensured, and multiple corrections need to be performed to ensure the stability of subsequent installation.

[0045] Step 302, after the construction of the main structure 4 of the underground second floor is completed, the underground first floor outer wall 2 below the first inner support 3 and the temporary purlin 6 thereon are constructed, so that the temporary purlin 6 is connected to the foundation pit retaining structure 1. Specifically, the embedded steel plate 7 is welded to the main reinforcement of the temporary purlin 6, and the embedded position of the embedded steel plate 7 should match the connection point of the force transmission rod 123 to ensure the stability of force transmission.

[0046] Step 303, after the construction of the underground first floor exterior wall 2 and the temporary purlin 4 is completed, start installing each assembled preloaded guy system 100. Place the standard section frame 112 on the embedded parts 111 of the underground second floor main structure 4, use high-strength bolts 116 to connect the standard section frame 112 and the embedded parts 111 of the underground second floor main structure 4, and ensure that the connection is firm and not loose. According to the depth of the foundation pit on site, install the standard section frame 112 step by step, and connect the standard section frame 112 and the anti-support frame 113 to each other through the high-strength bolts 116 through their respective flanges 115 and lock them. Each connection needs to be accurately calibrated with a torque wrench to ensure that there will be no loose connection or structural deformation during the subsequent loading process. The force transmission beam 125 is installed at the step surface 114 at the top of the anti-support frame 113 to withstand the reaction force of the jack 121.

[0047] Step 304, after installing the anti-support frame 113 and the pad 117 thereon, place the jack 121 on the pad 117 of the anti-support frame 113, and one end of the force transmission rod 123 is connected to the jack 121 through the flexible head 122. The length of the force transmission rod 123 needs to be adjusted according to the actual construction requirements, and the tightness of the flexible head 122 also needs to ensure that the stability of the force transmission rod 123 can be maintained when subjected to force. The force transmission rod 123 is connected to the temporary purlin 6 through the embedded steel plate 7, and then connected to the foundation pit retaining structure 1 through the temporary purlin 6. After the installation is completed, the jack 121 and the force transmission rod 123 are subjected to a preliminary loading test to ensure that each node of force transmission is in a stable state.

[0048] Step 305, after the assembled preloading support system 100 is installed, the preloading operation is performed. Use the jack 121 to apply a gradually increasing jacking force to the foundation pit retaining structure 1, and the force value needs to be precisely controlled according to the design value calculation. During the preloading process, the working status of the jack 121 and the deformation of the foundation pit retaining structure 1 need to be monitored at all times to ensure that all parts of the system 100 are evenly stressed during loading, and to avoid deformation of the foundation pit retaining structure 1 due to local force concentration. During the loading process, the monitoring equipment should collect data such as the displacement and stress change of the foundation pit retaining structure 1, so as to adjust the loading force in real time and ensure that the system is in the best working condition.

[0049] Step 306, after the preloading operation is completed, the first inner support 3 is gradually removed. After the first inner support 3 is removed, the construction of the underground main structure 8 begins. The preloading system continues to provide support at this time to ensure that the foundation pit retaining structure 1 does not move or deform during the construction process. During construction, care should be taken to avoid the support position of the preloading system 100 to ensure that the construction equipment and operation will not affect the normal operation of the system. The underground main structure 8 and the underground second main structure 4 both include structural floor slabs, structural columns, structural beams and other building components.

[0050] Step 307, after the construction of the underground main structure 8 is completed, the assembled preloaded support system 100 is dismantled, and the preload force of the jack 121 is gradually released to ensure that the foundation pit retaining structure 1 will not be displaced due to sudden loss of support during the unloading process. After the unloading is completed, the jack 121 and the force transmission rod 123 are removed, and the standard section frame bodies 112 and the anti-support frame 113 of the assembled reaction frame 120 are dismantled in turn. In this way, the recycling and reuse of each assembled preloaded support system 100 is realized.

[0051] The assembled preloaded towing system 100 provided in the embodiment of the present invention has a setting relationship between the various components, including but not limited to fixed connection methods such as welding, detachable connection methods such as bolting, and abutment connection methods such as contact connection, which can be appropriately selected according to the positions of the various components at different nodes.

[0052] The present invention is not limited to the above-mentioned specific implementation modes. Obviously, the above-mentioned embodiments are only some embodiments of the embodiments of the present invention, but not all embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention. Those skilled in the art can make other levels of modifications and changes to the present invention. In this way, if these modifications and changes of the present invention fall within the scope of the claims of the present invention, the present invention is also intended to include these changes and changes.

Claims

1. An assembled preloaded towing system, characterized in that: It includes an assembled reaction frame which is vertically installed on the structural floor of the underground second-story main structure below the first inner support close to the foundation pit retaining structure, and a loading device which is horizontally arranged between the assembled reaction frame and the foundation pit retaining structure close to the first inner support.

2. The assembled preloaded towing system according to claim 1, characterized in that: The loading device comprises a jack and a force transmission rod which is adjustably connected to the jack via a flexible head.

3. The assembled preloaded towing system according to claim 2, characterized in that: The assembled reaction frame comprises at least one standard frame body which is detachably connected to the structural floor of the underground second-floor main structure below the first inner support through embedded parts and a reaction support frame which is detachably connected thereto.

4. The assembled preloaded towing system according to claim 3 is characterized in that: The upper end of the reverse support frame is a step surface, and the loading device is horizontally arranged between the step surface and the foundation pit retaining structure.

5. The assembled preloaded towing system according to claim 4, characterized in that: The loading device is arranged on the foundation pit retaining structure through a temporary purlin horizontally arranged between the upper end surface of the outer wall of the underground first floor and the foundation pit retaining structure.

6. The assembled preloaded towing system according to claim 5, characterized in that: The jack of the loading device is arranged on the step surface of the anti-support frame, and the force transmission rod of the loading device is connected to the temporary purlin through the embedded steel plate placed on the temporary purlin.

7. The assembled preloaded towing system according to claim 6, characterized in that: The end face of the jack is arranged on the step elevation of the step surface through the end steel plate and multiple groups of force transmission beams between the end steel plate and the step elevation between the low-order horizontal surface and the high-order horizontal surface of the step surface.

8. The assembled preloaded towing system according to claim 7, characterized in that: The jack is installed on the lower level surface of the step surface through a pad.

9. A construction method for an assembled preloaded towing system according to any one of claims 1 to 8, characterized in that: include: After the construction of the main structure of the underground second floor is completed, multiple assembled reaction frames are vertically installed on the structural floor slab of the main structure of the underground second floor below the first inner support close to the foundation pit retaining structure; A loading device is horizontally arranged between each of the assembled reaction frames and the foundation pit retaining structure near the first inner support to form a plurality of assembled preloaded towing support systems; Before the first inner support is removed, a jacking force is applied to the foundation pit retaining structure through each loading device, so that after the first inner support is removed, the foundation pit retaining structure on the side is supported by each assembled preloaded support system.

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