Horizontal reciprocating loading device for spatial timber structure ancient building model

Abstract

A kind of horizontal reciprocating loading device for space timber structure ancient building model belongs to the field of seismic performance evaluation of timber structure ancient building. According to the current research status of space timber structure ancient building, a kind of pseudo-static loading device which can apply horizontal reciprocating load to space timber structure is developed by using H-shaped steel, steel plate, screw rod and other components, electro-hydraulic servo actuator, tensile and compressive force sensor, wireline displacement meter, data acquisition instrument and other instruments. The feasibility of the device in practical application is verified through test. The loading device is mainly used for pseudo-static loading of space timber structure ancient building model, and the seismic performance of timber structure model can be analyzed according to the measured test data. The device has many advantages such as easy control, large range, high precision, wide application range and so on.

Description

TECHNICAL FIELD

[0001] The device belongs to the field of seismic performance evaluation of wood structure ancient buildings. BACKGROUND

[0002] Wood structure building, as the main structure form of ancient buildings in China, has the characteristics of non-renewable and irreplaceable resources, and is the main carrier of the civilization history of Chinese nation for thousands of years, with high historical, cultural and artistic value. Many wood structure ancient buildings can stand for thousands of years, which shows that they have excellent seismic performance. However, a large amount of data shows that in the past earthquakes, the non-structural components of wood structure ancient buildings, such as walls, doors, windows and roof, have been damaged to varying degrees. Since the value of the components of ancient buildings is non-renewable, the damage of the value components will have an irreversible impact on the value characteristics of the building. Therefore, it is necessary to study the performance of wood structure ancient buildings under the action of earthquake, so as to protect the wood structure ancient buildings more effectively and accurately.

[0003] At present, scholars have done a lot of experimental research on the force performance of single components such as mortise and tenon joints, dougong, beams and columns of wood structure ancient buildings, and single frame of wood structure. The research on spatial wood structure is mainly based on shaking table test, and there are very few tests on the force performance of spatial wood structure by pseudo-static test method. Pseudo-static test, also known as low-frequency cyclic loading test, is a static test in which the structure or structural component is subjected to multiple repeated cyclic loading. It is a process of repeated loading and unloading in positive and negative directions to simulate the stress and deformation characteristics of the structure in the process of repeated vibration under earthquake. The loading rate of pseudo-static test is very low, so the stress and strain rate caused by loading rate can be ignored, and the pseudo-static test can maximize the use of test specimens to provide various basic information. Compared with shaking table test, pseudo-static test can stop at any time to observe the cracking and failure state of the structure, facilitate the test data and instrument working condition, and can modify and change the loading history according to the test needs. Therefore, it is necessary to explore a suitable loading device for pseudo-static test of spatial wood structure. Based on the force characteristics of wood structure building, the device applies electro-hydraulic servo system, tension-compression force sensor and tension displacement meter to invent a horizontal reciprocating loading device suitable for seismic performance evaluation of spatial wood structure.

[0004] Electro-hydraulic servo system refers to the hydraulic control system with servo element (servo valve or servo pump) as the control core, which is usually composed of command device, controller, amplifier, hydraulic source, servo element, execution element, feedback sensor and load. Electro-hydraulic servo actuator is a hydraulic actuator, which can convert hydraulic energy from hydraulic source into mechanical energy, and can also be servo-controlled through the displacement sensor or travel switch provided by the product according to the needs. It is used to execute the command of the main controller, control the speed, direction, displacement and force of the load, and feedback the signal output force to the main controller. It has the advantages of large output force, strong load capacity, large power density, fast response and high control precision, and is widely used in aviation, power generation, steelmaking, automobile, shipbuilding, material testing and other industries. Electro-hydraulic servo actuator is mainly composed of hydraulic servo valve, hydraulic actuator, displacement sensor, pressure sensor, load sensor, shock absorber and other elements. SUMMARY

[0005] The application utilizes H-shaped steel, steel plate, screw rod and other components, and electro-hydraulic servo actuator, tension-compression type force sensor, wire type displacement meter, and Donghua data acquisition instrument to develop a device that can apply horizontal reciprocating load to a spatial wood structure model. The device can perform low-cycle repeated loading on the model through load control or deformation control, so as to establish the restoring force characteristics of the structural model under the action of earthquake, obtain the equivalent damping ratio of the structure through the hysteresis curve obtained by the test, measure the energy dissipation capacity of the structure, and also obtain the skeleton curve, initial stiffness of the structure and stiffness degradation and other parameters. Thus, the seismic performance of the spatial wood structure can be further judged and identified from the aspects of strength, deformation and energy. In addition, the failure mechanism of structural components and joints can be obtained, which provides a basis for the protection and repair of ancient wood structure buildings.

[0006] A spatial wood structure ancient building model horizontal reciprocating loading device, characterized in that: it comprises a reaction wall (1), an electro-hydraulic servo actuator (2), a Φ31 nut (3), a Φ31 screw rod (4), a load distribution beam steel plate (5), a load distribution beam (6), a tension-compression type force sensor (7), a Φ42 nut (8), a wire type displacement meter (9), a force sensor steel plate (10), a Φ24 screw rod (11), a Φ24 nut (13), a wood structure model (14), and a wood structure model steel plate (12).

[0007] The actuator steel plate is connected to the counter-force wall (1) through a screw rod and a nut, the electro-hydraulic servo actuator (2) is installed on the actuator steel plate, the load distribution beam is anchored on the electro-hydraulic servo actuator (2) through two load distribution beam steel plates (5), four Φ31 screw rods (4) and eight Φ31 nuts (3), the left and right sides of the load distribution beam are the load distribution beam steel plates (5), the upper and lower sides are two Φ31 screw rods (4), the load distribution beam (6) is anchored by tightening the Φ31 nuts (3); the threads of the tension-compression force sensor (7) are threaded through the round holes on the web plate of the load distribution beam (6), steel pads are placed on both sides of the web plate, the Φ42 nuts (8) are tightened to connect the load distribution beam (6) and the tension-compression force sensor (7), the left side of the tension-compression force sensor (7) is connected to the force sensor steel plate (10) through the welded Φ42 nuts (8); the tensioned wire type displacement meter (9) is installed at the middle position of the upper end of the force sensor steel plate (10), the displacement meter is selected to be magnetic suction type, the tensioned wire type displacement meter (9) is adsorbed on the force sensor steel plate (10), and the other end of the tensioned wire type displacement meter (9) is connected to the counter-force wall (1); four Φ24 screw rods (11) pass through the holes in the four corners of the force sensor steel plate (10) and the wood structure model steel plate (12) respectively, and then the Φ24 nuts (13) on both sides of the force sensor steel plate (10) and the wood structure model steel plate (12) are tightened to anchor the wood structure model (14) together.

[0008] 2. The method for applying the horizontal reciprocating loading device for a spatial wood structure ancient building model, characterized in that:

[0009] When the electro-hydraulic servo actuator (2) applies pressure to the wood structure model (14), the pressure of the electro-hydraulic servo actuator (2) is transmitted to the tension-compression force sensor (7) at both ends through the load distribution beam (6), and the two tension-compression force sensors (7) apply pressure to the top of the right wood column (16) of the wood structure model (14) through the force sensor steel plate (10); when the electro-hydraulic servo actuator (2) applies tension to the wood structure model (14), the tension of the electro-hydraulic servo actuator (2) is transmitted to the tension-compression force sensor (7) through the load distribution beam (6), and the tension of the tension-compression force sensor (7) is transmitted to the wood structure model steel plate (12) through the force sensor steel plate (10) and the Φ24 lead screw (11), thereby applying pressure to the top of the left wood column (16) of the wood structure model (14); the direction and size of the load are controlled by the electro-hydraulic servo system, and the horizontal reciprocating load of the wood structure model (14) is realized; during the loading process, the tension-compression force sensor (7) not only plays a role in transmitting the load, but also can measure the size of the pressure and tension; the tension-compression force sensor (7) and the tension-compression force sensor (7) measure the displacement of the top of the wood column (16) of the wood structure model (14); the data measured by the tension-compression force sensor (7) and the tension-compression force sensor (9) are transmitted in real time and stored to the computer end through the data acquisition instrument, and after the test, the collected data are arranged and analyzed to obtain the corresponding load-displacement curve; two groups of tension-compression force sensors (7) and tension-compression force sensors (9) obtain two groups of load-displacement curves; the loading process of the electro-hydraulic servo system itself obtains a group of load-displacement curves, and by analyzing the three groups of load-displacement curves, the restoring force characteristics, equivalent damping ratio, skeleton curve and stiffness degradation of the wood structure are obtained, and the seismic performance of the space wood structure is further judged and identified from the strength, deformation and energy dissipation.

[0010] The innovation of the present application is that: on the basis of fully studying the stress characteristics of wood structure, reasonably arranging each component and instrument, a new type of space wood structure pseudo-static loading device is created, the problem of applying horizontal reciprocating load to space wood structure is solved, and the feasibility of the device in practical application is verified through test. The electro-hydraulic servo actuator loading is easy to control and ensures the range and precision of loading; the tension-compression force sensor can measure tension and pressure, which meets the requirements of reciprocating loading; the tension-compression force sensor and the tension-compression force sensor have a large range and high precision, which improves the range and measurement precision of the loading device; the Donghua data acquisition instrument has multiple acquisition channels, which can simultaneously acquire and store the electric signals of the tension-compression force sensor and the tension-compression force sensor, and is convenient for arranging and analyzing the test data in the later period. In summary, the horizontal loading device of the present application has the advantages of easy control, large range, high precision, wide application range and the like. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a schematic diagram of the loading device as a whole.

[0012] Figure 2 Figure 1 is a schematic diagram of the connection of the load distribution beam.

[0013] Figure 3 Figure 2 is a schematic diagram of the connection of the force sensor steel plate and the pull-wire displacement meter.

[0014] Figure 4 Figure 3 is a schematic diagram of the connection of the force sensor steel plate and the wood structure model steel plate.

[0015] Figure 5 Figure 4 is a schematic diagram of the wood frame model.

[0016] In the figure:

[0017] 1 counter-force wall 2 electro-hydraulic servo actuator 3 Φ31 nut

[0018] 4 Φ31 screw 5 load distribution beam steel plate 6 load distribution beam

[0019] 7 tension-compression force sensor 8 Φ42 nut 9 pull-wire displacement meter

[0020] 10 force sensor steel plate 11 Φ24 screw 12 wood structure model steel plate

[0021] 13 Φ24 nut 14 wood structure model 15 stiffening rib

[0022] 16 wood column 17 five-frame beam 18 purlin

[0023] 19 pad 20 purlin 21 three-frame beam

[0024] 22 gold melon column 23 ridge melon column DETAILED DESCRIPTION

[0025] The components and instruments used by the loading device from right to left are: counter-force wall (1), electro-hydraulic servo actuator (2), Φ31 nut (3), Φ31 screw (4), load distribution beam steel plate (5), load distribution beam (6), tension-compression force sensor (7), Φ42 nut (8), pull-wire displacement meter (9), force sensor steel plate (10), Φ24 screw (11), Φ24 nut (13), wood structure model (14), wood structure model steel plate (12).

[0026] Because of the large deformation and small stiffness of the wood structure model (14), a large stroke and high precision electro-hydraulic servo actuator should be selected. The selected electro-hydraulic servo actuator (2) in the loading device has a stroke of 0-1000 mm and a load of 0-10 t. The split load beam steel plate (5) is a square steel plate with a side length of 400 mm and a thickness of 20 mm. Holes are opened at the four corners of the split load beam steel plate (5), and the diameter of the holes is 34 mm. The distance from the center of the hole to the edge of the steel plate is 77.5 mm. The length of the Φ31 screw rod (4) is 500 mm. According to the stress characteristics of the wood structure model, the HW type steel with a length of 2600 mm, a height of 200 mm, and a width of 204 mm is selected as the split load beam (6) to meet the strength and stiffness requirements. A certain number of stiffening ribs (15) are welded in the direction perpendicular to the web of the split load beam (6), and a hole with a diameter of 44 mm is opened in the center at a distance of 100 mm from the edge of the web. The force sensor steel plate (10) is a square steel plate with a side length of 400 mm and a thickness of 20 mm. Holes are opened at the four corners of the steel plate, and the diameter of the holes is 26 mm. The distance from the center of the hole to the edge of the steel plate is 50 mm. A Φ42 nut (8) is welded at the center of one side of the force sensor steel plate (10). The length of the Φ24 screw rod (11) is 2000 mm. The wood structure model steel plate (12) is a square steel plate with a side length of 400 mm and a thickness of 20 mm. Holes are opened at the four corners of the steel plate, and the diameter of the holes is 26 mm. The distance from the center of the hole to the edge of the steel plate is 50 mm.

[0027] The wood structure model is composed of 4 wooden columns (16), 2 five-frame beams (17), 5 eaves (18), 5 cushion plates (19), 5 purlins (20), 4 gold melon columns (22), 2 three-frame beams (21), and 2 ridge melon columns (23) from bottom to top. The wood structure model (14) is made according to the style of the post-and-lintel ancient building wood structure, and the nodes between the components are connected by mortise and tenon joints.

[0028] The connection method of each component and instrument is as follows: the actuator steel plate is connected to the counter-force wall (1) through the screw rod and the nut, the electro-hydraulic servo actuator (2) is installed on the actuator steel plate, so as to realize the up-down and left-right adjustment of the electro-hydraulic servo actuator (2), and achieve the purpose of loading the wood structure model (14) at different positions and different heights. The load distribution beam is anchored on the electro-hydraulic servo actuator (2) through two load distribution beam steel plates (5), four Φ31 screw rods (4) and eight Φ31 nuts (3), the left and right sides of the load distribution beam are the load distribution beam steel plates (5), the upper and lower sides are two Φ31 screw rods (4) respectively, and the load distribution beam (6) is anchored by tightening the Φ31 nut (3). The thread of the tension-compression type force sensor (7) is threaded through the round hole on the web plate of the load distribution beam (6), steel pads are placed on both sides of the web plate, the Φ42 nut (8) is tightened to connect the load distribution beam (6) and the tension-compression type force sensor (7), the left side of the tension-compression type force sensor (7) is connected to the force sensor steel plate (10) through the welded Φ42 nut (8). The tension wire type displacement meter (9) is installed at the upper end of the force sensor steel plate (10), the displacement meter is selected as magnetic type, and only needs to be adsorbed on the force sensor steel plate (10), and the other end of the tension wire type displacement meter (9) is connected to the counter-force wall (1). Four Φ24 screw rods (11) pass through the holes in the four corners of the force sensor steel plate (10) and the wood structure model steel plate (12) respectively, and then the Φ24 nuts (13) on both sides of the force sensor steel plate (10) and the wood structure model steel plate (12) are tightened, so that the wood structure model (14) can be anchored together.

[0029] When the electro-hydraulic servo actuator (2) exerts pressure on the wood structure model (14), the pressure of the electro-hydraulic servo actuator (2) is transmitted to the tension-compression force sensor (7) at both ends through the load distribution beam (6), and the two tension-compression force sensors (7) exert pressure on the top of the right wood column (16) of the wood structure model (14) through the force sensor steel plate (10). When the electro-hydraulic servo actuator (2) exerts tension on the wood structure model (14), the tension of the electro-hydraulic servo actuator (2) is transmitted to the tension-compression force sensor (7) through the load distribution beam (6), and the tension of the tension-compression force sensor (7) is transmitted to the wood structure model steel plate (12) through the force sensor steel plate (10) and the Φ24 lead screw (11), thereby exerting pressure on the top of the left wood column (16) of the wood structure model (14). By controlling the direction and size of the load of the electro-hydraulic servo system, horizontal reciprocating loading of the wood structure model (14) can be realized. During the loading process, the tension-compression force sensor (7) not only serves to transmit the load, but also can measure the size of the pressure and tension. The tension-compression force sensor (7) and the tension-compression force sensor (7) can measure the displacement of the top of the wood column (16) of the wood structure model (14). The data measured by the tension-compression force sensor (7) and the tension-compression force sensor (9) can be transmitted in real time and stored to the computer end through the Donghua data acquisition instrument. After the test, the collected data are arranged and analyzed, and the corresponding load-displacement curve can be obtained. Two groups of tension-compression force sensors (7) and tension-compression force sensors (9) can obtain two groups of load-displacement curves. The loading process of the electro-hydraulic servo system itself can also obtain a group of load-displacement curves. By analyzing the three groups of load-displacement curves, the restoring force characteristics, equivalent damping ratio, skeleton curve and stiffness degradation of the wood structure can be obtained, and thus the seismic performance of the space wood structure can be further judged and identified from the aspects of strength, deformation and energy dissipation.

Claims

1. A horizontal reciprocating loading device for a spatial wooden ancient building model, characterized in that: Includes reaction wall (1), electro-hydraulic servo actuator (2), Φ31 nut (3), Φ31 screw (4), load-sharing beam steel plate (5), load-sharing beam (6), tension and compression force sensor (7), Φ42 nut (8), wire displacement gauge (9), force sensor steel plate (10), Φ24 screw (11), Φ24 nut (13), wooden structure model (14), wooden structure model steel plate (12); electro-hydraulic servo actuator (2) has a stroke of 0-1000mm and a load of 0-10t; The actuator steel plate is connected to the reaction wall (1) by screw rods and nuts. The electro-hydraulic servo actuator (2) is installed on the actuator steel plate. The load-sharing beam is anchored to the electro-hydraulic servo actuator (2) by two load-sharing beam steel plates (5), four Φ31 screw rods (4), and eight Φ31 nuts (3). The load-sharing beam has load-sharing beam steel plates (5) on the left and right sides, and two Φ31 screw rods (4) on the top and bottom sides. The load-sharing beam (6) is anchored by tightening the Φ31 nuts (3). The thread of the tension-compression force sensor (7) is passed through the round hole on the web of the load-sharing beam (6). Steel pads are placed on both sides of the web. The Φ42 nuts (8) are tightened to connect the load-sharing beam (6) and the tension-compression force sensor (7) together. The left side of the force sensor (7) is connected to the force sensor steel plate (10) by a welded Φ42 nut (8); a pull-wire displacement gauge (9) is installed at the middle position of the upper end of the force sensor steel plate (10). The displacement gauge is magnetic and can be attached to the force sensor steel plate (10). The other end of the pull-wire displacement gauge (9) is connected to the reaction wall (1); four Φ24 screw rods (11) are passed through the holes at the four corners of the force sensor steel plate (10) and the wooden structure model steel plate (12), and then the Φ24 nuts (13) on both sides of the force sensor steel plate (10) and the wooden structure model steel plate (12) are tightened to anchor the wooden structure model (14) together.

2. The method of using the horizontal reciprocating loading device for a spatial wooden ancient building model as described in claim 1, characterized in that: When the electro-hydraulic servo actuator (2) applies pressure to the wooden structure model (14), the pressure of the electro-hydraulic servo actuator (2) is transmitted to the tension-compression force sensors (7) at both ends through the load-bearing beam (6). The two tension-compression force sensors (7) apply pressure to the top of the wooden column (16) on the right side of the wooden structure model (14) through the force sensor steel plate (10). When the electro-hydraulic servo actuator (2) applies tension to the wooden structure model (14), the tension of the electro-hydraulic servo actuator (2) is transmitted to the tension-compression force sensor (7) through the load-bearing beam (6). The tension of the tension-compression force sensor (7) is transmitted to the wooden structure model steel plate (12) through the force sensor steel plate (10) and the Φ24 lead screw (11), thereby applying pressure to the top of the wooden column (16) on the left side of the wooden structure model (14). The direction and magnitude of the loading are controlled by the electro-hydraulic servo system to achieve the horizontal loading of the wooden structure model (14). Reciprocating loading; during the loading process, the tension-compression force sensor (7) not only plays the role of transmitting the load, but also can measure the magnitude of the pressure and tension; the wire displacement gauge (9) measures the displacement of the top of the wooden column (16) in the wooden structure model (14); the data measured by the tension-compression force sensor (7) and the wire displacement gauge (9) are transmitted in real time through the data acquisition instrument and stored on the computer. After the test, the collected data are sorted and analyzed to obtain the corresponding load-displacement curves; two sets of tension-compression force sensors (7) and wire displacement gauges (9) obtain two sets of load-displacement curves; the loading process of the electro-hydraulic servo system itself obtains a set of load-displacement curves. By analyzing the three sets of load-displacement curves, the restoring force characteristics, equivalent damping ratio, skeleton curve and stiffness degradation of the wooden frame are obtained. Thus, the seismic performance of the space wooden structure can be further judged and identified from the perspectives of strength, deformation and energy dissipation.

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