Building Frame System.pptx

Building Frame System

1. BUILDING FRAME SYSTEM

2. Building frame system A structural system with an essentially complete space frame providing support for vertical loads. Seismic lateral force resistance is provided by shear walls or braced frames.

3. Braced frame An essentially vertical truss, or its equivalent, of the concentric or eccentric type that is provided in a building frame system or dual system to resist lateral forces . The   braced framing   is generally used for the development of metal and wooden buildings. Beams and columns are estimated under the vertical loads, assuming that the bracing system helps all lateral loads. It relies on the bracing system to move the lateral system to the  foundation: horizontal and vertical bracing methods are used.

4. Advantages of Braced Frame structure: Due to bracing, lateral story displacement, story drift, axial force and bending moment in columns reduces to a notable level. The braced frames resist the wind and seismic forces more than the non-braced buildings. It is cost-effective, easy to erect and flexible to design to get required strength and stiffness. Disadvantages of braced frame structure: Altitude-dependent changes in seismic region. The length of the span is usually restricted to 40 feet when reinforced. Construction of these frames requires skilled labor.

5. SHEAR WALL A wall designed to resist lateral forces parallel to the plane of the wall . Shear wall is a structural member in a reinforced concrete framed structure to resist lateral forces such as wind forces. Shear walls are generally used in high-rise buildings subject to lateral wind and seismic forces.

6. Types of shear walls Wooden framing with vertical studs and sheathing.  This is the most common form of shear wall in US buildings. The wood frame with vertical studs alone is subject to deformation and collapse, and so the frame is covered in sheathing, typically plywood or oriented strand board (OSB). This assures that it remains rigid even under lateral pressure. Steel .  For larger buildings, these shear walls consist of steel sheets rather than plywood. Diagonal braces.  Whether made of steel or another material, a diagonal brace within a frame provides even more support. Moment frames.  These are rigid, rectilinear structures that function as shear walls but allow you to install a window or door in them. The cost of materials and labor to construct them make this an expensive option. 

7. Moment Resisting Frame System The Moment-resisting frame is a rectilinear assemblage of beams and columns, in which the beams are rigidly attached to the columns. Resistance to lateral forces is provided mainly by rigid frame action by the development of bending moment and shear force in the frame members and joints .

8. Types of moment resisting frame: Reinforced concrete Connection: It is unique moment frames used as part of seismic force-resisting systems that are designed to resist earthquakes . Beams, columns, and their joints are proportional to the moment frame provided to resist the flexural, axial, and shearing actions as a result of building construction through multiple displacement cycles during strong earthquakes . Particular proportions and expansion requirements result in a frame capable to withstanding strong earthquakes without significant loss of stiffness or strength . Moment Resisting Connection : In moment resisting frames, the structural members are joined together using rigid joints, so that the moment-opposing framework relies on the joints to transfer the lateral load to the foundation . Both braced frame  and moment-resisting frame perform the same functions that are resisting lateral loads and provide stability, but different mechanisms are used in each system.

9. Difference between an Ordinary Moment Resistant Frame and Special Moment Resisting Frame: Ordinary Moment-Resisting Frame (OMRF ) A frame not meeting special detailing requirements for ductile behavior . These provide the least resistance to lateral motion and so are only recommended for zero/low seismic regions. Intermediate Moment Resisting Frame (IMRF ). A frame designed in accordance with section 412 (concrete-diaphragm ). IMFs are the next level up, designed to resist limited in elastic deformations as the result of lateral forces. Special Moment-Resisting Frames (SMRF ). A bending moment is a measure of bending effect that can occur when an external force is applied to a structural element . moment resisting frame specially detailed to provide ductile behavior.

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