What is the moment frame?
Moment frame is a box in the shape of a special moment or joint box that helps to resist wind and earthquake damage. The frame helps to bend the building as needed to remain the integrity of the building. There are three types of torque frames: common torque frames (OMF), intermediate torque frames (IMF) and special torque frames (SMF).
The word "Moment" at a term or joint applies to the strength that building experiences when they are in wind or earthquake conditions. When the strength is applied in such a way to the structural element that the element bends, the bending moment is called. The building faces two primary types of force. One is outer, caused by wind pressure. It is the same pressure that applies to a person if it stands in a strong wind. The second is the inner force, such as this earthquake, comes from the foundations. A person is experiencing something similar when he stands on a train that takes off quickly and is shaken from his feet up.
buildings are designed for bending with a slight moment and designTem to their former state. This is called elasticity. Like the rubber group, the building should not have a permanent change from stretching or slightly and temporary bending.
To survive a strong earthquake, the opposite principle is true. The building built correctly should have permanent damage after a large earthquake. The frame should bend and absorb energy without falling. The frame built incorrectly becomes fragile and breaks during difficult conditions. This was the case in Northridge in California in 1994, when the earthquake decimpled buildings and urged the implementation of new show practices with a picture of the moment.
Federal Emergency Management Agency (FEMA) has regulations to protect structures against considerable damage. They provide standards that buildings in high seismic areas of and outstanding intended, including the construction of torque frames. Frame systems can be classified into three main types.
The moment -free frame (OMF) is used in low seismic areas and is expected to remain elastic during regular conditions. They do not have strict standards that have a torque frame used in a highly seismic area. They are not intended to process any interstate drift, which means that floors should not move in relation to each other.
The middle torque frame (MMF) is used in low to medium seismic areas. The purpose is to resist some permanent damage after limited force. They are obliged to maintain a slight drift inters.
A special torque frame (SMF) is used in medium to high seismic areas. The purpose is to withstand significant permanent damage to a high level. Must maintain a high level of drift intermediates.