modern technology to reduce earthquake hazards

Use of modern technology to reduce earthquake hazards

Masoud Shahbazi Nia – Director of Research and Development of BastanPol Co.

“Earthquake is not earth’s temper, not its anger, in order to stay safe from harm, the plan must be”

Several months ago, earthquakes in different parts of our country have taken calm from the inhabitants of Iran, numerous seismicity and aftershocks, the failure of structures and components of non-instruments, the death and injury of compatriots, the anxiety of children and women, the fear and fear of sudden death, and Living in the parks and cars is the familiar landscape of this day and night in the quake-stricken areas.

Many earthquakes are not new and unknown phenomena occur in East Asia on a daily and weekly earthquake, as this phenomenon has become part of people’s lives, as if people have reconciled and accepted the earthquake. At the time of the earthquake, it is easy to imagine that their habitats will not be debris, they will safely preserve their peace so that the vibrations will end and then continue to their normal lives.

This achievement is the result of the efforts of engineers and researchers and the attention of the authorities of those countries to the subject of construction, while unfortunately in Iran, buildings are built with obsolete technologies that are the cause of many injuries and deaths and the quality and performance of the building It’s so low that it’s also destroyed by less than six earthquakes.

The situation is getting worse because not only residential homes are damaged, but also the most vital structures, such as hospitals, barracks, organizations and offices that should be used by citizens during a crisis, are also being destroyed. The only way to go through the current situation and to face up to the earthquake is to use world-class technologies and materials at the global level.

BastanPol Engineering Group is one of the leading companies in providing new construction technologies and designing earthquake resistant structures. With its twenty years of experience in designing, monitoring and performing buildings, its goal is to improve the quality of buildings and the production of resistant buildings. Natural threats such as earthquakes. The main areas of the ancient company are bridge design of earthquake resistant buildings using seismic separators.

The company, with the help of reputable companies producing seismic separators, offers several technical and management strategies to reduce the effects of the earthquake on the structure.

In conventional design , due to nonlinear deformations in structural and non-structural members, damage to and damage to the structure may occur, and the structure will be virtually unusable after severe earthquakes due to the destruction of permanent joints and deformations. . With the advent of technical knowledge and the experience of intense earthquakes, changes to the design rules of structures have been created and, while changing the design philosophy of structures, technologies such as seismic separation have been used. Using this method, the amount of seismic damage to the components of the device is reduced to the lowest possible. In this method, the structure is separated from its supports and is placed on supports that have a large lateral deformation. In the event of an earthquake, major deformations occur in the backbone and the structure vibrates with small deformations. The use of this technology improves the behavior of structures and the behavior of structures during large earthquakes remains largely resilient. In this system, the earthquake structure is replaced by an earthquake instead of dealing with earthquakes in buildings. That is, when an earthquake occurs, our structure is accompanied by earthquakes rather than a rigid body with earthquake forces. The forces absorb the earthquake and the structure of Mortal.

The use of seismic separators has been used in many recent years. According to experimental results, structures with this technology will have less seismic responses than conventional structures, and the structure can perform much better and continue to service after an earthquake without interruption. The BastanPol Engineering Group has devoted a number of projects to providing design services based on seismic separators, and hopes to utilize the know-how of the world and increase public awareness, in line with the developed countries of the world, safe and durable buildings for our compatriots to be designed and implemented. Slowly

 

BRB

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.

Design based on performance

In terms of performance-based design, seismic design methodology is a general approach to how earthquakes affect the design of structures. This section tries to show that this approach has become more and more comprehensive over time.

Powerful methods

Traditional building design methods have long been commonplace among civil engineers against an old earthquake. The purpose of these methods was to design structures against earthquakes in a simple way without the need for complex engineering calculations. Compared with the new methods that have been proposed in earthquake engineering several decades ago, these methods can be called force-based methods, because in them a certain force acts as a representative of the earthquake effect associated with gravity loads to the structure.

In Iran, the first earthquake code was published in the year 1311 following the earthquake of Buin Zahra.

The first, second, third, and fourth editions of Iran’s 2800 standard were approved in the years 1367, 1378, 1383 and 1394, respectively.

The general framework of this method is based on the calculation of a specific force demand with a given value and the design of members of the structure with the ability to withstand that power. Below are some of the characteristics of this view in the seismic design:

  • In the regulations based on this methodology, the safety of the survivors is insured against collapse due to the collapse of the damages to the structures and the introduction of significant damage to the structures.
  • In this method, although the nonlinear behavior of the construct is recognized and used in design, this behavior is replaced by simulating a non-real equivalent linear behavior. This is somehow non-linear behavior implicit and indirect.
  • Structural performance in these methods during and after the earthquake is defined qualitatively and generally, and the behavior of the expected structure and its components have been ignored.
  • One of the main approaches in this approach is to use a behavior factor (R) to reduce seismic demand on the structure. Using this idea, which involves taking into account the structural strength of the load bearing, the forces used in the analysis take on an abstract and non-realistic nature, sometimes referred to as quasi-power.
  • In these regulations, an important coefficient (I) is used to take into account the higher expectations that behavior of some buildings, such as hospitals, occurs during an earthquake. This coefficient increases the design force for these buildings.
  • In Order 2800, in addition to the criteria of force, criteria are also given for controlling the structural hardness through the control of structural changes.

First generation performance-based methods

As noted above, routine seismic design techniques, with the simplicity of a complex behavior, provide plenty of detail, allowing the construction of nonlinear realms to the public for engineers, even without complex analysis and the use of advanced computing tools.

Performance-based approaches to earthquake engineering have been developed since the mid-80’s. Performance-based methods by identifying different levels of earthquakes focus on structural performance during and after the earthquake.

The general purpose of these methods is to reduce the damage to the members of the instrument and the non-structural by dividing the different levels for the performance of the structural components under different levels of input quake.

In these methods, achieving a desirable behavior of the structure is proposed as expected. For example, based on one of the expected functions, the structure is expected to behave in an encounter with a certain level of the earthquake so that the lives of the inhabitants can be avoided by avoiding its general collapse. Such functions are described in terms of the following functional levels:

  • Failure to collapse in large earthquakes is very rare
  • Providing safety in rare large earthquakes
  • Adoption of limited and repairable damage in moderate earthquakes
  • No damage in small and intermittent earthquakes

These functional levels are directly related to the entry of structural components into nonlinear realms. As much as this entry is greater, the structure will suffer more damage and show a lower performance (Figure 1).

Functional levelDescription of the damage situation
۱٫ Uninterrupted usabilityMinor system damage, main system performance, total damage to the entire structure
۲٫ ImmunityProbable damage occurrence, non-collapse, minimal level of risk of collapse, appropriate emergency exit
۳٫ The threshold of its fallSevere damage, early fall, danger of collapse, limited access

Functional methods, in comparison with traditional methods, provide more possibilities for designers and increase the designer’s view by increasing the parameters involved in designing and observing the structure’s behavior more accurately.