Wooden structure low cycle repeated horizontal loading test device

Wooden structure low cycle repeated horizontal loading test device

Wooden structure repeated horizontal loading test device

Static load test system for timber shear walls

Wooden structure low cycle repeated horizontal loading test system

Wooden shear wall static load and low cycle repeated horizontal loading test system

Wooden structure low cycle repeated horizontal loading test device,Suitable for determining the lateral performance of timber shear wall systems under static and low cycle repeated loads under horizontal action, including failure mode, load, ultimate displacement, load displacement curve, hysteresis curve of reciprocating loads, and skeleton curve.

Shear Wall:A wall made of wood-based structural panels or gypsum boards for the surface layer, and standard materials for wall studs and columns to withstand vertical and horizontal forces.

Covering board:Wooden based structural panels or gypsum boards are used as cladding panels for wooden shear walls.

Wooden based structural panels:Load bearing boards made from wood as raw material (rotary cut wood, wood chips, sawdust, etc.) through bonding and pressing, including structural plywood and directional wood chip boards.

Anti pull fasteners:Steel components and bolts are used to connect and fix the end wall bone columns and foundation beams of the wooden shear wall, effectively resisting upward pulling force. They are installed at both ends of the wooden shear wall specimen to provide sufficient vertical constraints.

Full length anchoring screw:The top and bottom beams of the wooden shear wall specimen are connected by bolts and fixed to the loading beam and foundation beam of the experimental equipment. The full-length screws are installed at both ends of the wooden shear wall specimen to provide vertical restraint.

Hysteresis curve:The load displacement curve obtained under the cyclic action of force reflects the deformation characteristics, stiffness degradation, and energy consumption of the structure during repeated stress, and is the basis for determining the restoring force model and conducting nonlinear seismic response analysis.

Skeleton curve:The envelope curve obtained by sequentially connecting the extreme points of loads loaded in the same direction (tensile or compressive) on the hysteresis curve.

a) Example of End Constraints b)Example of full-length disc round screwc)Example of Combined Compressive Load d)Example of combined tensile load

The testing equipment should be able to perform horizontal loading with an accuracy of ± 1% F and ± 1% l or higher, and continuously record loads and displacements.

When horizontal lateral load F and vertical load F are applied simultaneously, the testing equipment should be able to control the horizontal lateral load and vertical load separately, and it is recommended to consider frictional resistance. The method of applying vertical loads refers to the fact that vertical loads should not generate horizontal force components. When applying vertical loads, the influence of their horizontal force components should be considered in experiments and data processing.

In Method I, the shear capacity of the shear wall specimen is achieved by applying sufficient vertical loads and vertical constraints (such as anti pull fasteners) or by using full-length staggered screws (placed at the upper and lower ends of the shear wall specimen in low cycle repeated testing).

When using anti pull fasteners, they should first be able to effectively resist the upward pulling force, and at the same time, the additional resistance applied by the anti pull fasteners to the shear wall should be determined.

The goal of Method I is to induce shear failure in the shear wall specimen itself. Therefore, when designing shear wall specimens, consideration should be given to preventing the shear wall from collapsing and buckling. It is recommended to use anti pull fasteners at the top of shear wall specimens when horizontal or vertical loading is not separately considered. When using a full-length staggered screw, frictional resistance should be taken into account.

In Method II, shear wall specimens should be tested based on representative boundary conditions (such as anchoring and anti pull fastener details) and vertical (compression and tension) load conditions in actual engineering.

Method II can lead to the failure of shear wall specimens, anchorages, or vertical restraints (anti pull fasteners).

Measurement point A should be as close as possible to the top of the shear wall specimen.

Static load (monotonic) test

The horizontal lateral load F should be applied as shown in Figure 1, and the load should be steadily and continuously applied based on the reading of displacement meter A. When the loading or unloading value is less than or equal to 0.4F..., the loading rate should be (0.0008H ± 0.0002H) mm/min. When the load is greater than 0.4F..., the loading rate should be able to achieve the ultimate displacement of the specimen within 5-30 minutes. The load time curve for applying horizontal lateral load is shown in Figure 2. The load deformation curve is shown in Figure 3

Instructions:

X - Time, seconds (s);

A stable loading cycle;

B - stiffness loading cycle;

One - Strength testing.

Figure 2 Load Time Curve

The displacement of the shear wall specimen should be observed at points A, B, C, and D (as shown in Figure 1). The deformation lm is the displacement of point A minus the displacement of point B. The displacement of points C and D should be reported separately.

The average value of the ultimate displacement for static load testing should be as shown in Figure 4. Determine the definition.

Instructions:

X - deformation, millimeters (mm);

Figure 3 Load deformation curve

Instructions:

X - displacement l; Y - load F;

2. Displacement of damage points;

3-F (Example c);

4-1 (Example a), displacement of the failure point;

b—1, (Example b), displacement at 0.8F;

-1 (Example e), displacement=H/15

Definition of ultimate displacement: F corresponds to any of the following three situations, including: displacement at the failure point (example a), displacement at 0.8F after the load point (example b), or displacement at H/15 (example e), and the situation that occurs in the above three situations shall prevail.

Figure 4 Determination method of ultimate displacement under different failure conditions

6.2 Low cycle repeated testing program

The low cycle repeated displacement testing program should be able to provide;

a) Data that can fully demonstrate the elastic and inelastic periodic characteristics of shear wall specimens;

b) Representative requirements for earthquake action on shear wall specimens.

The low cycle repeated displacement program shown in Figure 5 should reach the ultimate displacement within 1 minute to 30 minutes. The amplitude of low cycle repeated loading is the ultimate displacement 1 obtained in static (monotonic) testing. The function of the average value (where applicable). Table 1 represents the loading amplitude by multiplying the ultimate displacement by the corresponding percentage, or a low cycle repeated displacement program that meets the above principles and can achieve the test objectives (such as based on speed or frequency) can be used.

Instructions:

X - Time, seconds (s);

Y - Displacement, 1. Multiply by percentage.

Figure 5 Low cycle repeated displacement program

Under the premise of meeting 6.2, certain initial loading steps (1.25% 1,~10% 1) can be omitted or repeated (or added) based on the stiffness of the shear wall specimens and the accuracy of the measurement system. B. 4 specifies the situations where the standard low cycle repeated displacement program can be changed.

7 Test Results

7.1 Hysteresis data

All hysteresis data (load displacement) of each tested shear wall specimen should be plotted and stored. When processing raw data, time, input displacement, measured load, and measured displacement should be included,

7.2 Skeleton Curve

1、 The second and third skeleton curves should be the lines connecting the load points on each hysteresis curve. The maximum load and corresponding displacement for the first five cyclic cycles should be plotted on all skeleton curves. See Figure E.1 for an example.

7.3 Performance of shear wall specimens

During low cycle repeated testing, the loads and ultimate displacements in both directions of the three skeleton curves (as defined in Figure 3) should be

Table based staffing report.