Dual structural system based on positive and negative stiffness

Abstract

This invention is a new structural system consisting of two components. In this system, the structure consists of a central part and an outer part. The two parts are connected by roller elements that allow the vertical sliding of the two parts. One of the two structural elements is placed on a pendulum system and the other part of the structure is placed on an inverted pendulum system. This combination improves the behavior of the structure during an earthquake and prevents its destruction.

Description

Description of the invention Title of the invention "Dual structural system based on positive and negative stiffness" Technical background of the relevant invention This system is used in the field of vibrations and earthquakes. Technical problem and stating the objectives of the invention The phenomenon of earthquakes at the urban and industrial levels, the issue of absorbing and controlling vibrations, and the maintenance of seismically sensitive devices can be considered the main technical problem for this system. The proposed invention, by combining a pendulum isolator with a system with negative stiffness capability, improves the performance of the structure during an earthquake by increasing the isolator frequency. A description of the state of the prior art and the history of developments related to the claimed invention. The way vertical and lateral loads are transferred in steel and concrete structures depends on the combination and arrangement of the vertical load-bearing members of the structure, such as columns, beams, and lateral load-bearing members, such as braces, and the way these members are structurally connected. This combination is called the structural system. Types of structural systems are categorized as follows from the perspective of Code 2800: Load-bearing wall system Building frame system Bending frame system Dual or hybrid system Console system These systems are usually either used normally or placed on seismic isolators. In the first-story columns of this type of structure, energy is stored in the form of strain energy, and destruction occurs due to the accumulation of strain energy in the foundations. When using the isolator, these structural systems do not change, but in the proposed system, the connections of the structure itself are also modified to improve the performance of the structure during an earthquake. As seen in most articles, negative stiffness is usually created with pre-compressed springs. In reality, creating such springs that can support the weight of the structure and at the same time be operational is either impossible or very challenging. However, in the proposed system, the part of the structure that is placed on the two-ended columns relies on gravity to create negative stiffness, which is completely possible and simple. Providing a solution to an existing technical problem along with an accurate, sufficient, and integrated description of the invention This invention is a structural system consisting of two components (3 and 5). In this system, the structure consists of a central part (5) and an outer part (3). This combination improves the behavior of the structure during an earthquake and prevents its destruction. The two sections are connected by roller elements (4) that allow vertical sliding of the two sections. One of the two structural components is placed on the pendulum system (1) and the other part of the structure is placed on the inverted pendulum system (2). With the above description, one component of the structure oscillates at a certain frequency and the other part tends to overturn at a similar rate. The combination of the two systems increases the natural oscillation of the structure and moves the structure to a safe area (according to the reflection coefficient diagram) during an earthquake. It is even possible to achieve a quasi-zero stiffness zone. Both the pendulum and the inverted pendulum sections store energy in the form of potential. This is in contrast to structural columns where energy is stored in the form of strain energy. Therefore, failure due to strain energy accumulation does not occur in these foundations. In short, the structure is divided into two components with a pendulum action (with positive stiffness) and an inverted pendulum action (with negative stiffness), which is even capable of creating a region with pseudo-zero stiffness. Explanation of shapes, maps and diagrams Figure 1: Simplified specification map of the new structural system 1-Positive stiffness providing member (pendulum separator) 2-Member providing negative stiffness (inverted pendulum) 3-External mass or structure 4-Roller connector or two-end joint 5-Central mass or structure Figure 3 and 2: Specification map of the new structural system A clear and precise statement of the advantages of the claimed invention over prior inventions. According to the above, this system can be used in mechanical structures under vibration and earthquake load or other structures. The proposed system adds negative stiffness to the system by applying an eccentric force. It increases the isolator frequency, causing a shift in the structure period and reducing the base shear force during an earthquake. Description of at least one implementation method for implementing the invention This system can be built and implemented using existing methods and conventional technologies for manufacturing mechanical parts and does not require any special methods. Explicit mention of the industrial application of the invention This system can be used in structures and for devices sensitive to shock and vibration, replacing conventional structural systems.

Claims

Claim What is claimed: Claim 1) This system is a new structural system that improves the behavior of the structure during an earthquake by changing the connection of the structure to the ground. This system consists of the following components: Central structure Outer structure Connecting structure between two structures Pendulum supports Inverted pendulum supports Claim 2) According to claim 1, the two inner and outer parts of the structure are connected by connecting components. These components allow the two structural components to slide relative to each other. Claim 3) Referring to claim 1, one of the structural components (the inner or outer part of the structure) is placed on the two end members of the joint and acts like an inverted pendulum. Claim 4) According to claim 1, the other part of the structure rests on the pendulum members and acts like a pendulum. Claim 5) According to claims 1, 3, and 4, this structural combination increases the overall natural frequency of the structure and improves the behavior of the structure during an earthquake.

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