Advantages of Structural Steel
Some advantages associated with the use of structural steel for owners :
• Steel favors for reduced frame construction time and the proficiency to formulate in all seasons.
• Steel creates large spans and bay sizes possible, contributing more pliability for owners.
• Steel is smoother to modify and reinforce if constructive shifts are made to a facility over its life.
• Steel is lightweight and can decrease foundation expenses.
• Steel is reliable, durable and recyclable.
2. Individual prospects of Steel Construction
Acquisition and management of structural steel is identical to other materials, but there are some particular prospects to steel construction:-
• Steel is formulated off-site.
• On-site erection is a accelerated process.
• This delivers users of structural steel some scheduling profits.
• Coordination of all parties is indispensable for accomplishing possible favors.
3. Forces on Structures
• Forces from gravity, wind, and seismic crises are instituted on all structures.
• Forces that show vertically are gravity loads.
• Forces that perform horizontally, such as stability, wind and seismic events involve lateral load resisting systems to be set up into structures.
• As lateral loads are administered to a structure, horizontal diaphragms (floors and roofs) dispatch the load to the lateral load resisting system.
• The form of lateral load resisting system to be wielded in a structure should be recognized beforehand in the planning stage.
• Lateral stability and architectural demands must be reached.
The three common lateral load resisting systems are:-
· Braced Frames
· Rigid Frames
· Shear Walls
4. Steel Frame Connection Types
• Simple Connections
• Moment Connections: Fully-Restrained and Partially-Restrained • All connections have a undeniable amount of rigidity.
• Simple connections (A above) have some rigidity but are expected to be free to rotate.
• Partially-Restrained moment connections (B and C above) are devised to be semi-rigid.
• Fully-Restrained moment connections (D and E above) are created to be fully rigid.
5. Simple Connections
• Devised as amenable connections
• Connections are expected to be able to rotate
• Vertical shear forces are the primary forces carried by the connection
• Involve a independent bracing system for lateral stability
• The successive few slides establish some prevalent simple framing connections.
6. Moment Combinations
• Fashioned as rigid connections that favor little or no rotation, Used in rigid frames.
• Moment and vertical shear forces are carried through the connection.
• Two types of moment connections are endorsed: Fully-Restrained and Partially-Restrained.
7. Rigid Frames
• Rigid frames, exploiting moment connections, are well fitted for distinct forms of buildings where diagonal bracing is not practical or does not fit the architectural design.
• Rigid frames commonly cost more than braced frames.
8. Braced Frames
• Diagonal bracing shapes stable triangular configurations within the steel building frame.
• Braced frames are usually the most cost-effective method of resisting wind loads in multi-story buildings.
• Some structures, like the one envisioned above, are devised with a consolidation braced and rigid frame to take advantage of both.
9. Temporary Bracing
• Structural steel frames obligate temporary bracing during construction
• Temporary bracing is spotted before plumbing up the structural frame
• This hands over the structure temporary lateral stability
• Temporary bracing is excluded by the erector
• In a braced frame, temporary bracing is get rid of after final bolt-up is done and the permanent bracing system is in place
• In a rigid frame, short-lived bracing is removed after final bolt-up is complete
10. Concentric Braced Frames
Bracing is concentric when the center lines of the bracing members intersect. . Bracing can favor a building to have approach through the brace line rely up on the configuration. Common concentric braced frames adopted in buildings today cover:-
· X brace
· Two-story X’s
· Chevron
· Single diagonals
11. X Bracing
• X bracing is probably the most familiar type of bracing.
• The diagonal members of X bracing go into tension and compression identical to a truss.
• The multi-floor building frame elevation revealed above has just one braced bay, but it may be mandatory to brace many bays along a column line
• With this in mind, it is remarkable to decide the locations of the braced bays in a structure beforehand in a project
• Connections for X bracing are situated at the beam to column joints.
• Bracing connections may obligate comparatively large gusset plates at the beam to column joint
• The constraint of space in these areas may have an consequence on the mechanical and plumbing systems as well as some architectural features.
12. Chevron Bracing
• The members adopted in Chevron bracing are composed for both tension and compression forces
• Chevron bracing favors for doorways or corridors through the bracing lines in a structure
• Chevron bracing members use two types of connections.
• The floor level connection may adopt a gusset plate much like the connection on X braced frames
• The bracing members are attached to the beam/girder at the top and concentrate to a common point
• If gusset plates are used, it is relevant to scrutinize their size when laying-out mechanical and plumbing systems that pass through braced bays.
13. Eccentrically Braced Frames
• The contrast between Chevron bracing and eccentric bracing is the space between the bracing members at the top gusset connection
• Eccentric bracing is regularly used in seismic zones and favors for doorways and corridors in the braced bays
• In an extremely braced frame bracing members attach to separate points on the beam/girder
• The beam/girder segment or “link” between the bracing members takes in energy from seismic activity through plastic deformation
• Eccentrically braced frames look identical to frames with Chevron bracing
• An akin V-shaped bracing configuration is utilized.
14. Combination Frames
• A braced frame deflects like a cantilever beam while a moment-resisting frame deflects more or less routinely from top to bottom
• By associating the two systems, decreased deflections can be comprehended.