Fabricated prestressed self-centering frame beam-column replaceable energy dissipation node

Abstract

This invention discloses a prefabricated prestressed self-resetting frame beam-column replaceable energy-dissipating node, comprising a node core area connection device, a short steel beam connector, an RC frame beam connector, a replaceable energy-dissipating device, a self-resetting device, a pin, and a friction pad. The node core area connection device includes a partition plate, a clamp, and a short steel beam. The short steel beam connector includes a fixing plate, an anchoring plate, and an outer friction lug. The RC frame beam connector includes an inner friction lug, an RC frame beam connecting end plate, and an embedded H-beam. The clamp is connected to the fixing plate via the short steel beam, and the outer friction lug, inner friction lug, and friction pad are connected to form a friction energy-dissipating device. The pin rotates with the friction energy-dissipating device. The anchoring plate and the RC frame beam connecting end plate are connected via the replaceable energy-dissipating device. The RC frame beam connecting end plate is connected to the longitudinal reinforcement of the beam. This invention, through the ingenious design of two energy-dissipating devices, avoids the deficiency that the energy dissipation level of the structure can only be at a low level after the failure of a single type of energy-dissipating component.

Description

Technical Field

[0001] This invention relates to a replaceable energy-dissipating node for prefabricated prestressed self-resetting frame beams and columns, belonging to the field of structural engineering. Background Technology

[0002] Currently, the seismic design goals are "no damage in minor earthquakes, repairable damage in moderate earthquakes, and no collapse in major earthquakes." However, even if buildings achieve these goals, they often suffer significant residual deformation and irreparable damage after an earthquake, necessitating demolition and resulting in substantial resource waste. Therefore, there is an urgent need to develop beam-column connection technologies for frame structures that offer deformation recovery, strong energy dissipation capacity, and high load-bearing capacity.

[0003] Among existing self-resetting joint technologies, those utilizing SMA (Shape Memory Alloy) materials are costly, and the performance of SMA materials is significantly affected by temperature and loading methods, thus hindering their large-scale application. In contrast, prestressed self-resetting reinforced concrete (RC) frame structures, under seismic loading, have prestressed tendons in an elastic phase, with seismic energy primarily dissipated by energy-dissipating components. The RC frame suffers minimal or no damage. Post-earthquake, only the energy-dissipating components need to be replaced to achieve rapid structural function restoration. Furthermore, under the action of the prestressed tendons, the structure can self-reset, achieving controllable residual deformation.

[0004] Currently, many research results have been achieved on prefabricated prestressed self-setting reinforced concrete (RC) frame structures, but most of them focus on the structural form of the beam-column joints of self-setting RC frames to verify energy dissipation capacity and reset characteristics. However, for prefabricated RC frame structures with replaceable energy dissipation components, the following two issues still need to be studied: First, energy dissipation level and reset capacity are often difficult to balance simultaneously; how to achieve a balance between the two, ensuring strong energy dissipation capacity while minimizing residual deformation, requires further research. Second, how to implement different energy dissipation modes in different deformation stages, so that prefabricated RC frame structures have good energy dissipation levels and reset capabilities in minor, moderate, and major earthquakes, is also a challenge. Summary of the Invention

[0005] This invention provides a replaceable energy-dissipating node for prefabricated prestressed self-resetting frame beams and columns. By cleverly designing two types of energy-dissipating devices—a replaceable energy-dissipating device and a friction energy-dissipating device—it avoids the deficiency that the energy dissipation level of the structure can only be at a low level after the failure of a single type of energy-dissipating component.

[0006] The technical solution of the present invention is: a prefabricated prestressed self-resetting frame beam-column replaceable energy-consuming node, including a node core area connection device 2, a short steel beam connector 3, an RC frame beam connector 4, a replaceable energy-consuming device 5, a self-resetting device 7, a pin 10, and a friction pad 13.

[0007] The node core area connecting device 2 includes a partition plate 201, a clamp 202, and a short steel beam 203. The partition plate 201 is installed inside the clamp 202. The partition plate 201 has a round hole in the middle and small holes at the edges of the partition plate 201 for the column longitudinal reinforcement to pass through. The partition plate 201, the column longitudinal reinforcement, and the column stirrups tied to the outside of the column longitudinal reinforcement are formed by pouring concrete to create an RC frame column 1 extending along a first direction. The short steel beam 203 is installed on the outside of the clamp 202 along a second direction, so that one end of the short steel beam 203 is connected to the clamp 202. The first direction and the second direction are perpendicular to each other.

[0008] The short steel beam connector 3 includes a fixed plate 301, an anchor plate 302, and an outer friction ear plate 303 connected in sequence; the RC frame beam connector 4 includes an inner friction ear plate 401, an RC frame beam connecting end plate 402, and an embedded H-beam 403 connected in sequence; the fixed plate 301 is connected to the other end of the short steel beam 203, and the outer friction ear plate 303, the inner friction ear plate 401, and the friction pad plate 13 arranged from the outside to the inside are connected to form a friction energy dissipation device; the pin 10 passes through the friction energy dissipation device, and the two are rotatably engaged; the anchor plate 302 and the RC frame beam connecting end plate 402 are connected by a replaceable energy dissipation device 5; the RC frame beam connecting end plate 402 is connected to the beam longitudinal reinforcement 12 located on the side of the RC frame beam connecting end plate 402 away from the short steel beam connector 3, and the embedded H-beam 403, the beam longitudinal reinforcement, and the beam stirrups tied outside the beam longitudinal reinforcement are used to form an RC frame beam 6 by pouring concrete.

[0009] The self-resetting device 7 is arranged along the second direction and is sequentially connected to the anchor plate 302, passes through the RC frame beam connecting end plate 402, and the RC frame beam 6 before being anchored to the RC frame beam anchor end plate 11.

[0010] Furthermore, two partition plates 201 arranged in parallel along the second direction are installed inside the clamp 202; the short steel beam 203 is an H-shaped steel beam, and the centroids of the upper and lower flanges of the two partition plates 201 and the H-shaped steel beam are at the same height.

[0011] Furthermore, the replaceable energy-consuming device 5 includes a left bottom plate 501, an energy-consuming plate 502, and a right bottom plate 503; the two energy-consuming plates 502 are symmetrically installed between the left bottom plate 501 and the right bottom plate 503; the left bottom plate 501 is fixed to the anchor plate 302 by a second high-strength bolt, and the right bottom plate 503 is fixed to the RC frame beam connecting end plate 402 by a steel sleeve 9, which is connected to the third high-strength bolt and the longitudinal reinforcement 12 of the RC frame beam.

[0012] Furthermore, the self-resetting device 7 is in four sets, each including prestressed steel strands 701 and anchors 702; the prestressed steel strands 701 are fixed by anchors 702 by tensioning them diagonally one by one.

[0013] The beneficial effects of this invention are:

[0014] First, the present invention effectively reduces the residual deformation of the structure by using post-tensioned unbonded prestressed steel bars, and realizes the self-resetting of the structure after an earthquake.

[0015] Second, the structural damage of the present invention is concentrated on the replaceable energy-consuming device, which is easy to replace, and realizes the rapid restoration of the structural function after the earthquake.

[0016] Third, by adjusting the design parameters of the replaceable energy dissipation device and the friction energy dissipation device, the present invention achieves a reasonable match between the two energy dissipation modes, so that only friction energy dissipation is used during minor and moderate earthquakes, and friction energy dissipation and the replaceable energy dissipation device are used together during major earthquakes, thereby enabling the structure to have good energy dissipation and recovery capabilities at different deformation stages.

[0017] Fourth, the prestressed steel bars are tensioned on the ground at the construction site and then hoisted into place, connected to the short steel beams with high-strength bolts. This avoids the dangerous operation of tensioning prestressed steel bars at height. It also avoids the risk of a significant reduction in prestress within multi-span beams if the prestressed steel bars tensioned throughout the span fail.

[0018] Fifth, by setting up two energy-consuming devices, the present invention has a high degree of safety redundancy, avoiding the deficiency that the energy consumption level of the structure can only be at a low level after the failure of a single type of energy-consuming component. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention;

[0020] Figure 2 This is a three-dimensional schematic diagram of the steel-concrete joint core area connection device of the present invention;

[0021] Figure 3 This is a schematic diagram of the partition plate in the core area of ​​the steel-concrete joint of the present invention;

[0022] Figure 4 This is a three-dimensional schematic diagram of the short steel beam connector of the present invention;

[0023] Figure 5 This is a three-dimensional schematic diagram of the RC frame beam connector of the present invention;

[0024] Figure 6 This is a three-dimensional schematic diagram of the replaceable energy-consuming device of the present invention;

[0025] Figure 7 This is a three-dimensional schematic diagram of the longitudinal reinforcement and steel sleeve connection of the RC frame beam of the present invention;

[0026] Figure 8 This is a schematic diagram of the friction pad device of the present invention;

[0027] Figure 9 This is a top view of the friction energy dissipation device of the present invention;

[0028] Figure 10 This is a schematic diagram of the prestressed steel strand of the present invention;

[0029] Wherein: 1-RC frame column; 2-Node core area connection device; 201-Partition plate; 202-Clamping band; 203-Short steel beam; 3-Short steel beam connector; 301-Fixing plate; 302-Anchoring plate; 303-Outer friction ear plate; 4-RC frame beam connector; 401-Inner friction ear plate; 402-RC frame beam connection end plate; 403-Embedded H-beam; 5-Replaceable energy dissipation device; 501-Left bottom plate of energy dissipation plate; 502-Energy dissipation plate; 503-Right bottom plate of energy dissipation plate; 6-RC frame beam; 701-Prestressed steel strand; 702-Anchor; 9-Steel sleeve; 10-Pin shaft; 11-RC frame beam anchoring end plate; 12-RC frame beam longitudinal reinforcement; 13-Friction pad plate. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0031] Example 1: As Figure 1-10 As shown, a prefabricated prestressed self-resetting frame beam-column replaceable energy-consuming node includes a node core area connection device 2, a short steel beam connector 3, an RC frame beam connector 4, a replaceable energy-consuming device 5, a self-resetting device 7, a pin 10, and a friction pad 13.

[0032] Reference Figure 2 , Figure 3The node core area connecting device 2 includes a partition plate 201, a clamp 202, and a short steel beam 203. The partition plate 201 is installed inside the clamp 202. A circular hole is opened in the middle of the partition plate 201 to increase its embedding effect with the column concrete. Small holes are opened at the edges of the partition plate 201 for the column longitudinal reinforcement to pass through. The partition plate 201 inside the clamp 202, the column longitudinal reinforcement, and the column stirrups tied outside the column longitudinal reinforcement form an RC frame column 1 extending along a first direction by pouring concrete. A short steel beam 203 is welded and installed on the outside of the clamp 202 along a second direction, so that one end of the short steel beam 203 is connected to the clamp 202. The first direction and the second direction are perpendicular to each other. In specific applications, column stirrups are tied to the column longitudinal reinforcement extending outside the clamp 202. Specifically, refer to... Figures 1 to 3 The RC frame column 1 is a rectangular column. The RC column 1 is designed with longitudinal reinforcement and stirrups according to the specifications. The longitudinal reinforcement is arranged through the small holes of the partition 201. After the stirrups are tied, the formwork is completed and the concrete can be poured. After curing, the RC frame column 1 is obtained.

[0033] Furthermore, two partition plates 201 arranged in parallel along the second direction are installed inside the clamp 202; the short steel beam 203 is an H-shaped steel beam, and the centroids of the upper and lower flanges of the two partition plates 201 and the H-shaped steel beam are at the same height, thereby better transmitting the tensile and compressive forces on the upper and lower flanges of the short steel beam 203.

[0034] refer to Figure 4 The short steel beam connector 3 includes a fixing plate 301, an anchoring plate 302, and an outer friction lug plate 303 connected in sequence; (Reference) Figure 5 The RC frame beam connector 4 includes an inner friction ear plate 401, an RC frame beam connecting end plate 402, and an embedded H-beam 403 connected in sequence; the fixing plate 301 is connected to the other end of the short steel beam 203, and the outer friction ear plate 303, the inner friction ear plate 40, and the friction pad plate 13, arranged in close contact from the outside to the inside, are connected to form a friction energy dissipation device; the pin 10 passes through the friction energy dissipation device, and the two are rotatably engaged; the anchor plate 302 and the RC frame beam connecting end plate 402 are connected by a replaceable energy dissipation device 5; the RC frame beam connecting end plate 402 is connected to the beam longitudinal reinforcement 12 located on the side of the RC frame beam connecting end plate 402 away from the short steel beam connector 3, and the embedded H-beam 403, the beam longitudinal reinforcement, and the beam stirrups tied outside the beam longitudinal reinforcement are used to form an RC frame beam 6 by pouring concrete;

[0035] For example, such as Figure 2 , Figure 4As shown, the web of the short steel beam 203 has a first bolt hole. Two fixing plates 301 are symmetrically welded to one side of the anchor plate 302. The two fixing plates 301 are attached to the web of the short steel beam 203 located between them, and the short steel beam 203 and the fixing plates 301 are fixed together by first high-strength bolts. Figure 4 , Figure 5 , Figure 8 , Figure 9 As shown, the outer friction lugs 303 consist of two pieces symmetrically welded to the other side of the anchor plate 302, with a first pin hole in the middle and bolt holes along a circular curve. Two inner friction lugs 401 are symmetrically welded to one side of the RC frame beam connecting end plate 402, with a second pin hole in the middle and bolt holes along a circular curve. Sliding bolts on both sides pass sequentially from the outside to the inside through the bolt holes of the outer friction lugs 303, the bolt holes of the inner friction lugs 401, and the bolt holes of the friction pad 13, forming two pairs of symmetrical friction energy dissipation devices. The design of the bolt holes provides space for the sliding bolts to rotate smoothly. The pin 10 passes through the central circular hole of the symmetrically arranged outer friction lugs 303, inner friction lugs 401, and friction pad 13, forming a rotation center during stress, allowing the structure to rotate around the pin. To increase the bending resistance of the RC frame beam connecting end plate 402, an embedded H-beam 403 is welded to the RC frame beam connecting end plate 402. The embedded H-beam 403 has a round hole in the web position to increase the fixing effect with the RC frame beam 6.

[0036] Furthermore, the pin 10 is made of Cr40 alloy structural steel with superior comprehensive mechanical properties and must meet the shear bearing capacity requirements. The friction pad 13 should have a certain thickness to reduce the wear of the bolt on the inner friction lug 401 during rotation.

[0037] Furthermore, the replaceable energy-consuming device 5 includes a left bottom plate 501, an energy-consuming plate 502, and a right bottom plate 503; the two energy-consuming plates 502 are symmetrically welded between the left bottom plate 501 and the right bottom plate 503.

[0038] For example, such as Figure 4 , Figure 5 , Figure 6 , Figure 7As shown, the anchor plate 302 has a second bolt hole and a first prestressing tendon channel. Four second high-strength bolts pass through the second bolt holes to fix the left bottom plate 501 of the energy dissipation plate to the anchor plate 302. The RC frame beam connecting end plate 402 has a third bolt hole and a second prestressing tendon channel. A steel sleeve 9 connects the third high-strength bolt and the threaded RC frame beam longitudinal reinforcement 12 through the third bolt hole, thereby fixing the right bottom plate 503 of the energy dissipation plate to the RC frame beam connecting end plate 402. One end of the prestressed steel strand 701 passes through the first prestressing tendon channel and is anchored to the anchor plate 302 using anchor 702. The other end of the prestressed steel strand 701 exits from the second prestressing tendon channel and is anchored to the RC frame beam anchor end plate 11 using anchor 702. Figure 1 , Figure 7 As shown in the example, the replaceable energy-consuming device 5 is provided in two sets, and the connection method of the upper and lower replaceable energy-consuming devices 5 is the same.

[0039] In practical engineering, the energy dissipation performance of the replaceable energy dissipation device 5 can be adjusted by modifying the material, shape, and thickness of the energy dissipation plate 502, as well as the filling material between the energy dissipation plates. The energy dissipation performance of the friction energy dissipation device can be adjusted by changing the bolt preload and the friction material. The replacement energy dissipation device and the friction energy dissipation device work together to achieve the goal of staged energy dissipation with good energy dissipation and reset capabilities. After an earthquake, the replaceable energy dissipation device 5 can be quickly replaced by removing the high-strength bolts.

[0040] Furthermore, the self-resetting device 7 is arranged along the second direction and sequentially connects to the anchor plate 302, passes through the RC frame beam connecting end plate 402, and the RC frame beam 6 before being anchored to the RC frame beam anchor end plate 11.

[0041] Furthermore, the self-resetting device 7 comprises four sets, each including prestressed steel strands 701 and anchors 702; the prestressed steel strands 701 are fixed by the anchors 702 through diagonal, strand-by-stretching method. (Reference) Figure 1 , Figure 7 , Figure 8 , Figure 10The prefabricated prestressed self-resetting frame beam-column replaceable energy-dissipating nodes are symmetrically equipped with four unbonded prestressed steel strands 701. Each unbonded prestressed steel strand 701 is a 7-strand 1860 grade prestressed steel strand with a nominal diameter of 15.2 mm and an initial tension set to 0.3 to 0.5 times the ultimate tension. The prestressed steel strands 701 remain elastic under stress and function as a restorative element. Anchors 702 transfer the tension of the prestressed steel strands to the structure, increasing overall strength and providing a restorative function. One end of the anchor 702 is anchored to the anchor plate 302, and the other end is anchored to the RC frame beam anchor end plate 11. The RC frame beam anchor end plate 11 has holes at the prestressed steel strand locations to prevent localized pressure damage to the RC frame beam.

[0042] The working principle of the above-mentioned prefabricated prestressed self-resetting frame beam-column replaceable energy dissipation node is as follows: Under frequent earthquakes, both the main structure and the replaceable energy dissipation device 5 are in the elastic stage, and the friction energy dissipation device only undergoes slight rotation; under the design earthquake, the friction energy dissipation device rotates to a certain extent, providing small stiffness and large energy dissipation capacity. The replaceable energy dissipation device 5 does not participate in energy dissipation but provides large stiffness and bearing capacity. At this time, the node dissipates earthquake energy only through the friction energy dissipation device, and the replaceable energy dissipation device 5 is in the elastic working stage, so the structure does not need to be repaired; under rare earthquakes, the energy dissipation plate 502 of the replaceable energy dissipation device 5 yields and enters the plastic working stage, thereby providing greater energy dissipation capacity and higher ductility. The friction energy dissipation device rotates fully, thereby continuously providing friction energy dissipation; at this time, the node dissipates energy through the plastic deformation of the energy dissipation plate 502 and the rotational friction of the friction energy dissipation device. Other structural components are still in the elastic stage or only a small part enters the elastic-plastic stage. After the earthquake, its function can be restored by replacing the replaceable energy dissipation device 5.

[0043] This invention also discloses a construction method for the above-mentioned precast prestressed self-resetting beam-column joint, comprising the following steps:

[0044] 1) Connect the core area of ​​the standardized production node in the factory with the following components: 2, short steel beam connector 3, RC frame beam connector 4, replaceable energy-consuming device 5, steel sleeve 9, pin 10, and friction pad 13; weld, drill holes, and thread according to the above requirements.

[0045] 2) Binding of RC frame beam 6 and RC frame column 1, positioning and fixing of steel components, formwork, pouring, and curing. It should be noted that RC frame beam 6 is used for the prestressing tendon duct through which the prestressed steel strands 701 pass, and is formed by PVC pipes placed during the binding of the tendons.

[0046] 3) Align the short steel beam connector 3, RC frame beam connector 4, and friction pad 13, and install the pins; align the replaceable energy dissipation device 5, and tighten the left and right bolts to the design value respectively; symmetrically pass the bolts on both sides of the friction energy dissipation device through the outer friction ear plate 303, the inner friction ear plate 401, and the friction pad 13, and then tighten them to the design value.

[0047] 4) Tensile the prestressed steel strands 701 diagonally to the design tension value and anchor them at the factory or construction site ground. Hoist the composite beam components to the preset position and connect the short steel beams 203 and the short steel beam connectors 3 with high-strength bolts and tighten them to the design value.

[0048] As can be seen from the above technical solution, this invention, based on traditional precast concrete structures, fully utilizes the energy consumption characteristics of replaceable energy-consuming devices and friction energy-consuming devices to achieve different energy consumption modes at different deformation stages. Using prestressed steel strands as a reset method, it significantly reduces residual deformation after an earthquake. It effectively improves the energy consumption and reset capabilities of nodes, allowing for rapid restoration of structural function by replacing replaceable energy-consuming components after an earthquake. Simultaneously, prestressing tendons are tensioned on the ground and then hoisted into place, avoiding the dangerous operation of tensioning prestressing tendons at height through bolt connections, making the structural layout more flexible and convenient. Based on the design method proposed in this invention, the length of the short steel beam 203, the cross-sectional dimensions, strength grade and type (lightweight aggregate concrete, recycled concrete, etc.) of the RC frame beam 6, the type of friction energy-consuming device (brass friction plates, sandblasted), the material, thickness, shape of the replaceable energy-consuming plate 502, and the filling material between the plates, etc., can be further optimized to achieve the optimized design of this embodiment.

[0049] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A replaceable energy-dissipating joint for prefabricated prestressed self-resetting frame beams and columns, characterized in that, Includes node core area connection device (2), short steel beam connector (3), RC frame beam connector (4), replaceable energy consumption device (5), self-resetting device (7), pin (10), and friction pad (13); The node core area connecting device (2) includes a partition (201), a clamp (202), and a short steel beam (203); the partition (201) is installed inside the clamp (202), the partition (201) has a round hole in the middle, and the partition (201) has small holes at the edge for the column longitudinal reinforcement to pass through; the partition (201) inside the clamp (202), the column longitudinal reinforcement, and the column stirrups tied outside the column longitudinal reinforcement are formed by pouring concrete to form an RC frame column (1) extending along the first direction; the short steel beam (203) is installed on the outside of the clamp (202) along the second direction, so that one end of the short steel beam (203) is connected to the clamp (202); the first direction and the second direction are perpendicular to each other; The short steel beam connector (3) includes a fixing plate (301), an anchor plate (302), and an outer friction lug (303) connected in sequence; the RC frame beam connector (4) includes an inner friction lug (401), an RC frame beam connecting end plate (402), and an embedded H-beam (403) connected in sequence; the fixing plate (301) is connected to the other end of the short steel beam (203), and the outer friction lug (303), the inner friction lug (401), and the friction pad (13) arranged from the outside to the inside are connected to form a friction plate. The friction energy dissipation device; the pin (10) passes through the friction energy dissipation device and the two are rotatably engaged; the anchor plate (302) and the RC frame beam connecting end plate (402) are connected by a replaceable energy dissipation device (5); the RC frame beam connecting end plate (402) is connected to the longitudinal reinforcement (12) of the beam located on the side of the RC frame beam connecting end plate (402) away from the short steel beam connector (3); the embedded H-beam (403), the longitudinal reinforcement of the beam and the beam stirrups tied outside the longitudinal reinforcement of the beam are formed by pouring concrete to form an RC frame beam (6). The self-resetting device (7) is arranged along the second direction, and is connected to the anchor plate (302) in sequence, passes through the RC frame beam connecting end plate (402) and the RC frame beam (6), and is then anchored on the RC frame beam anchor end plate (11). The clamp (202) is equipped with two partitions (201) arranged in parallel along the second direction; the short steel beam (203) is an H-shaped steel beam, and the centroids of the upper and lower flanges of the two partitions (201) are at the same height as the centroids of the upper and lower flanges of the H-shaped steel beam; The replaceable energy-consuming device (5) includes a left bottom plate (501), an energy-consuming plate (502), and a right bottom plate (503); the two energy-consuming plates (502) are symmetrically installed between the left bottom plate (501) and the right bottom plate (503); the left bottom plate (501) is fixed to the anchor plate (302) by a second high-strength bolt, and the third high-strength bolt and the longitudinal reinforcement (12) of the RC frame beam are connected by a steel sleeve (9), thereby fixing the right bottom plate (503) of the energy-consuming plate to the connecting end plate (402) of the RC frame beam; The self-resetting device (7) consists of four sets, each including prestressed steel strands (701) and anchors (702); the prestressed steel strands (701) are fixed by anchors (702) through diagonal tensioning.

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