Structures in seismic environments require a system to withstand earthquake-side loads. This system must, in addition to the strength and toughness of the economy, be able to exhibit a high degree of irresponsible behavior in absorbing and deprecating energy. Historically, braces have been used since the end of the 19th century to maintain the sides of most of the world’s tallest buildings. For example, the Statue of Liberty, which was built in 1883 in New York, is one of the greatly curtained structures. Over the next three decades, a large number of tall buildings were constructed with a framed steel frame in Chicago and New York. The Wolverdeath 75-story building, with a height of 241 meters, completed in 1913, was the record-keeper of high-rise buildings at that time.
Conventional and effective side barrier systems can be used for lateral braking. The use of framed frames dates back to the early 20th century. The rigidity, resistance and economy of braced frames have made these systems one of the most commonly used sidewall systems in steel buildings in areas with high seismicity.
The design of bracing systems is within the non-economic reactionary range. Therefore, these systems are designed in the area of inertial deformations. The design of the system is such that the brace in large compressive forces slows down the buckler and surrenders in large tensile forces.
The idea of a buckling brace was first introduced in Japan in 1971. He suggested that the member could be crushed between concrete panels to prevent the buckling of a steel member. This system of bracing after the Nerisrij earthquake in the United States was welcomed and accepted and introduced relatively few rules in the US regulations.
In its buckling bracelets, the goal is to counteract the adverse effects of buckling bracing.
This design was corrected a few years later by a Japanese research team and led to what we know today as a curtain bracelet. In this study, the behavior of a kind of braid consisting of a steel core enclosed inside a steel barrier filled with mortar was examined and tested. The main idea behind this plan was to isolate the pressure load by the core and prevent the buckling of the core by a steel shield. The behavior of the steel core inside the shaft depends entirely on the relative difficulty of the core and the steel shield.
Another kind of twisty buckling brace is the buckling brace of all the steel. In this curtain, the inner core between the buckling mechanism is made of all steel so it is prevented from the cost of the mortar. The construction time is shorter and can be easily removed after an earthquake for inspection.
The components of the bracelet are as follows:
Restricted surrendered part: This steel section can have a rectangular cross section. This section is designed to surrender during cyclic loads. The soft steel, which has high viscosity, is desirable in this section.
Incompatible Inhibited Section: This section, which is enclosed through the inkjet mortar, is usually controlled by the suction side of the suction, but is high enough to ensure elastic behavior.
Unsupported non-intrusive section: This section usually involves the continuation of an unscrupulous part of the curtain used to attach the curtain to the frame.
Separator and Extender: A neutral material such as a rubber that can remove or minimize the shear force transmitted between the concealed steel and the used mortar.
Cast iron mechanism: This mechanism consists of a mortar or an enclosed steel, such as a hollow section.
Advantages of curtain braces
Some of the benefits of archery braces include:
Both in stretching and in a non-buckling flow, as a result of the ability to absorb high energy and during severe earthquakes, less damage occurs to interstices and non-structural components.
Easy replacement of damaged braces after a major earthquake.
They are very flexible, since it is easy to adjust their strength and hardness.
It is possible to adjust the bracing dimensions in order to equalize the need and seismic capacity, thus reducing the probability of concentration of damage in a floor.
Skeleton cost savings.
Compared to the flexural frames, they have higher elastic stiffness and can easily meet the criteria of relative displacement in seismic regulations.
Modeling the circular behavior of these braces is easy for nonlinear analysis.
The bracing strength is at a higher pressure than stretching, because the axial force in the pressure from the core is transferred to the buckling mechanism.
Disadvantages of Armchairs
Despite all the benefits of BRB brackets, there are some disadvantages that are mentioned below:
The parameters required for the design of BRBs made by different companies vary.
The regulations are necessary to determine the extent of damage to these braces.
Still, there are no standards for determining the extent of damage to these braces and the need to replace them with official references.
In large earthquakes, large permanent deformations in the system may be created, because it lacks a restorer mechanism.
There are a lot of problems caused by concrete in the area as well as heavy bracing.
It is not possible to inspect the bracing core after severe earthquakes.
The non-elastic hardness of BRBs is relatively low and decreases in each cycle relative to the previous cycle.