WO2024005727A1

WO2024005727A1 - Experimental setup for supported beams with variable vertical and rotational rigidities

Info

Publication number: WO2024005727A1
Application number: PCT/TR2022/050717
Authority: WO
Inventors: Babür DELİKTAŞ; Hakan Tacattin TÜRKER; Serkan SAĞIROĞLU
Original assignee: Bursa Uludağ Üni̇versi̇tesi̇
Priority date: 2022-07-01
Filing date: 2022-07-07
Publication date: 2024-01-04
Also published as: TR2022010910A2

Abstract

The invention is particularly related to an experimental setup developed to explain the basic concepts to students in engineering education, to observe the effect of semi-rigid support state (adjustable vertical and rotational rigidity), rotational rigidities at nodal points, semi-rigid joint types in joint regions (beam, frame, etc.) on the behavior of the structural system.

Description

EXPERIMENTAL SETUP FOR SUPPORTED BEAMS WITH VARIABLE VERTICAL AND ROTATIONAL RIGIDITIES

Technical Field

The invention relates to an experimental setup, which is suitable for use in engineering education, for bending tests and determination of rotational rigidity of beams with different support types (fixed, anchored, semi-rigid).

The invention is particularly related to an experimental setup developed to explain the basic concepts to students in engineering education, to observe the effect of semi-rigid support state (adjustable vertical and rotational rigidity), rotational rigidities at nodal points, semi-rigid joint types in joint regions on the behavior of the structural system (beam, frame, etc.).

Prior Art

Many experiments are carried out in engineering education to better explain the basic concepts to the students. As many teaching subjects, there are test kits as commercial products for bending tests and rotational rigidity.

Rotational rigidity is an important basic concept and a physical property that is considered in the analysis and design of engineering problems in many engineering fields. Today, there are many experimental kits to support engineering education; however, bending test equipment that takes into account semi-rigid support states to find rotational rigidity is not available in the current art.

In the literature, there is an article published under the title “Turker, H. T., Sagiroglu, S., and Deliktas, B., Experimental setup for beams with adjustable rotational stiffness: An educational perspective, Comput Appl Eng Educ. 2022; 30: 564- 574”. When the referenced article is examined, it is seen that only an experimental setup for adjustable rotational rigidity is explained. However, in addition to the variable rotational rigidity, variable vertical rigidities of the support is not included in the said description. Another document published in the same technical field on the subject is the application numbered CN204479399. The referenced document relates to the technical field of beam bending testing and in particular an adaptive support device for beam bending testing. The support device mentioned in the said document includes adjustment springs and a support plate but does not include an improvement for beams with vertical and rotational rigidity.

Another document found in the current art is the application with the publication number CN103487223A. The referenced document is about bending rigidity field tests of the sample under high and low temperature ambient conditions. The current technique is for measuring the bending rigidity of a structural member at high or low temperature and does not contain any innovations for beams with vertical and rotational rigidity.

In conclusion, in the face of the drawbacks described above and the inadequacy of the existing solutions on the subject, it has become necessary to make an improvement in the relevant technical field.

Purpose of the Invention

The invention is inspired by current situations and aims to solve the problems mentioned above.

The main purpose of the invention is to provide an experimental setup to observe the effects of semi-rigid support situation in load carrying systems (beam, frame, etc.), rotational rigidities at nodal points, and semi-rigid joint types at joints on the behavior of the system.

Another purpose of the invention is to provide an experimental setup for bending tests and rotational rigidity of beams with different support situations.

Another purpose of the invention is to provide an experiment kit order to better explain the basic concepts to students in fields such as engineering mechanics and structural statics.

Another purpose of the invention is provide to find the rotational rigidity at the tip of a deformable sample with an easy calculation. To achieve the purposes described above, the invention is an experimental setup to examine the effects of semi-rigid support state in structural systems such as beam and frame, that is, adjustable vertical and rotational rigidity, rotational rigidities at nodal points, and semi-rigid connection types in joint areas, on the behavior of the structural system, which provides the basic concepts to be explained to students in engineering education, characterized by comprising;

• a loading system that performs the loading on the beam,

• at least one bearing welded to the ends of the beam to provide support behavior, forming a support point for the beam,

• at least one spring suspension bar that connects it with the bearings located at the beam ends perpendicular to the beam axis and provides a rigid connection

• at least one spring suspension ring configured at specified distances from the bearing center on the spring suspension bar

• a support base on which the beam, bearing and spring suspension bar are supported

• a spring, which is attached between the spring suspension rings and the support base, that provides semi-rigid support of the beam ends and determines the rotational rigidity provided to the beam end.

The below drawings and the detailed description set out with reference to the accompanying drawings provide for a clearer understanding of the structural and characteristic properties and all benefits of the invention; For this reason, the evaluation should be made by taking these figures and detailed explanation into consideration.

Figures to Help Understanding of the Invention

Figure 1 is the general view of the experimental setup, which is the subject of the invention.

Figure 2a is the undeformed view of the beam support region.

Figure 2b is the undeformed view of the beam support region. Description of Part References

A. Experimental setup

1 . Loading system

2. Loading frame

10. Beam

11 . Potentiometer

12. Load cell

21 . Spring suspension bar

22. Spring

23. Spring suspension ring

24. Shaft

25. Bearing

26. Vertical motion guides

27. Vertical rigidity spring

28. Support base

29. Pedestal base

Detailed Description of the Invention

The preferred embodiments of the experimental setup (1 ), which is the subject of the invention, are described in this detailed description only for the purpose of a better understanding the subject.

The experimental setup (1 ), which is the subject of the invention, comprises in general, a loading frame (2), a loading system (1 ) provided in the said loading frame (2), a beam (10) as a test sample, at least one bearing (25) welded to the ends of the beam (10) to provide support behavior, forming a support point for the beam, at least one spring suspension bar (21 ) that connects it with the bearings (25) located at the beam ends perpendicular to the beam (10) axis and provides a rigid connection, at least one spring suspension ring (23) configured at specified distances from the bearing center on the spring suspension bar (21 ), a support base (28) on which the beam (10), bearing (25) and spring suspension bar (21 ) are supported, a spring (22), which is attached between the spring suspension rings (23) and the support base (28), that provides semi-rigid support of the beam ends and determines the rotational rigidity provided to the beam end. In addition, it includes a shaft (24) mounted on the support bases (28) and passed through the bearings (25) at the ends of the beam (10), allowing the beams to be mounted, and vertical movement guides (26) that provide the vertical movement of the support base (28) and prevent its horizontal movement. The support base (28) rests on vertical rigidity springs (27) that provide semi-rigid support in the vertical direction. Vertical rigidity springs (27) hold the vertical base (29) under them. Vertical movement guides (26) are used to prevent vertical movement guide (26) from turning due to the vertical movement of the bearing. The subject of the invention also has a potentiometer (11 ) that enables the measurement of the amount of deformation on the beam (10). In the experimental setup of the invention, there is also a load cell (12) that performs the load measurement. It reads the values of the load applied during the test.

The experimental setup (A) subject of the invention makes it possible to perform beam bending tests for different support situations. However, the rotational rigidity can be found by experiment and provides a simple calculation for the rotational rigidity. With the experimental setup of the invention, the rigidity of the springs (22) and the rotational rigidity can be calculated depending on the position of suspension.

As seen in Figure 1 , the experimental setup (A), which is the subject of the invention, is formed inside a loading frame (2), the inside dimensions of which are preferably approximately 120 cm x 75 cm. A steel bar (band) with a rectangular cross-section is used as a beam (10). A ball bearing (25) preferably with an outer diameter of 3 cm and an inner diameter of 1.5 cm is used to provide the support behavior. Two bearings (25) are welded to the ends of the beam (10). Steel bars with rectangular cross-section, preferably 3 cm wide and 2.5 cm high, are welded to the bearings (25) at the beam ends, in a position perpendicular to the beam axis, as spring suspension bars (21 ). This way, a rigid connection is provided between the end of the beam welded to the same bearing and the end of the spring suspension bar (21 ). The beams are mounted by passing the shafts (24) mounted on the support bases (28) through the bearings (25) at the ends of the beam (10). In order for the deformations in the spring suspension bars (21 ) to be negligible, the sections of these rods are chosen to be more rigid than the beam section. The center of the bearings (25) at the ends of the beam (10) is taken as the support point for the beam in the setup. There are spring suspension rings (23) on the spring suspension bars (21 ) at certain distances from the center of the bearing. The semi-rigid support of the beam ends (10) is provided by linear springs (22) to be fitted between the spring suspension rings (23) on the spring suspension bar (21 ) and the support base (28). The rigidity of these linear springs (22) and their suspended position (h) determine the rotational rigidity provided to the beam end. The expression of rotational rigidity in terms of the two mentioned parameters is derived below (Figure 2)

Figure 2(a) shows the undeformed state of the beam (10). In this state, it should be taken into account that the spring is connected in such a way that no force exerted (no pre-stressing) in the spring connected between the suspension bar (21 ) and the loading frame. As a result of the loading to be applied on the beam (10) (for example, a single loading to be made in the middle of the opening), the deformed state of the left support end will be as in Figure 2(b). Since the beam end and the spring suspension bar (21 ) are rigidly connected to each other at the support point, the rotation angle 0 at the beam end is equal to the rotation (0) at the spring suspension bar. If the spring constant of the linear spring used is ks and the elongation in the spring is denoted with u, the force that will occur in the spring can be written as:

F= ks x u (Eq. 1 )

Considering that the angle of rotation is small, the elongation (u) in the spring can be written as: u = 0xh (Eq. 2)

In this case, Equation 2 becomes the following.

F= ks x0xh (Eq. 3)

The moment generated at the support of the beam will be equal to the product of the rotational rigidity ( e) of the beam support and the rotational angle (0). This moment will be equal to the moment of the spring force (F) about the support point.

Fxh= ke x0 (Eq. 4)

Replacing F in this expression with its equivalent in Equation 4: ks x0xhxh= ke x 0 (Eq. 5)

Making necessary simplifications, we find; ke = k₅ *h² (Eq. 6)

Thus, when the rigidity of the linear spring and its suspended position are known, the rotational rigidity at the beam end can be easily found by using Equation 6. The case of not using a spring in the mechanism will correspond to the case of the articulated link (pin support), and the case of using a rigid bar instead of the spring will correspond to the case of the rigid link (fixed support).

Claims

CLAIMS An experimental setup (A) to examine the effects of semi-rigid support state in structural systems such as beam (10) and frame, that is, adjustable vertical and rotational rigidity, rotational rigidity at nodal points, and semi-rigid connection types in joint areas, on the behavior of the structural system, which provides the basic concepts to be explained to students in engineering education, characterized by comprising;

• a loading system (1 ) that performs the loading on the beam (10),

• at least one bearing (25) welded to the ends of the beam (10) to provide support behavior, forming a support point for the beam,

• at least one spring suspension bar (21 ) that connects with the bearings (25) located at the beam ends perpendicular to the beam (10) axis and provides a rigid connection

• at least one spring suspension ring (23) configured at specified distances from the bearing center on the spring suspension bar

• a support base (28) on which the beam (10), bearing (25) and spring suspension bar (21 ) are supported

• a spring (22), which is attached between the spring suspension rings (23) and the support base (28), that provides semi-rigid support of the beam ends and determines the rotational rigidity provided to the beam end. The experimental setup (A) according to claim 1 , characterized by comprising a shaft (24), which is mounted on bearing bases (28) and allows beams to be mounted by passing through bearings (25) at the end of the beam (10). The experimental setup (A) according to claim 1 , characterized in that the rigidity of the springs (22) and the rotational rigidity can be calculated depending on the position in which they are suspended. The experimental setup (A) according to claim 1 , characterized by comprising a vertical rigidity spring (27) upon which the bearing base (28) rests, that provides semi-rigid support in the vertical direction. The experimental setup (A) according to claim 1 , characterized by comprising vertical movement guides (26) that provide the bearing base (28) to move vertically, preventing horizontal movement. The experimental setup (A) according to claim 1 , characterized by comprising a potentiometer (11 ) that provides the amount of deformation to be measured on the beam (10).