Frame structures are the structures having the combination of beam, column and slab to resist the lateral and gravity loads. These structures are usually used to overcome the large moments developing due to the applied loading.
Types of frame structures
Frames structures can be differentiated into:
1. Rigid frame structure
Which are further subdivided into:
- Pin ended
- Fixed ended
2. Braced frame structure
Which is further subdivided into:
- Gabled frames
- Portal frames
Rigid Structural Frame
The word rigid means ability to resist the deformation. Rigid frame structures can be defined as the structures in which beams & columns are made monolithically and act collectively to resist the moments which are generating due to applied load.
Rigid frame structures provide more stability. This type of frame structures resists the shear, moment and torsion more effectively than any other type of frame structures. That's why this frame system is used in world's most astonishing building Burj Al-Arab.
Braced Structural Frames
In this frame system, bracing are usually provided between beams and columns to increase their resistance against the lateral forces and side ways forces due to applied load. Bracing is usually done by placing the diagonal members between the beams and columns.
This frame system provides more efficient resistance against the earthquake and wind forces. This frame system is more effective than rigid frame system
Pin Ended Rigid Structural Frames
A pinned ended rigid frame system usually has pins as their support conditions. This frame system is considered to be non rigid if its support conditions are removed.
Fix Ended Rigid Frame Structure:
In this type of rigid frame systems end conditions are usually fixed.
Gabeled Structural Frame:
Gabled frame structures usually have the peak at their top. These frames systems are in use where there are possibilities of heavy rain and snow.
Portal Structural Frame
Portal structural frames usually look like a door. This frame system is very much in use for construction of industrial and commercial buildings
Load path in Frame Structure:
It is a path through which the load of a frame structure is transmitted to the foundations. In frame structures, usually the load path is:
Load first transfers from slab to beams then to from beam to columns, then from columns it transfers to the foundation.
Advantages of Frame Structures
- One of the best advantages of frame structures is their ease in construction. it is very east to teach the labor at the construction site.
- Frame structures can be constructed rapidly.
- Economy is also very important factor in the design of building systems. Frame structures have economical designs.
Disadvantages of Frames:
In frames structures, span lengths are usually restricted to 40 ft when normal reinforced concrete. Other wise spans greater than that, can cause lateral deflections.
Comparison of Frame structures with Normal Load bearing Traditional High Rise Building
Selection of frame structures for the high rise building is due to their versatility and advantages over the normal traditional load bearing structures. These include the following:
Actually the performance of load bearing structures is usually dependent on the mass of structures. To fulfill this requirement of load bearing structures, there is the need of increase in volume of structural elements (walls, slab). This increase in volume of the structural elements leads toward the construction of thick wall. Due to such a type of construction, labor and construction cost increases. in construction of thick wall there will be the need of great attention, which will further reduce the speed of construction.
If we make the contrast of load bearing structures with the framed structures, framed structures appear to be more flexible, economical and can carry the heavy loads. Frame structures can be rehabilitated at any time. Different services can be provided in frame structures. Thus the frame structures are flexible in use.