Chapter 8 Composite Frames and Joints Prof.Shiming Chen 2013,May
Chapter 8 Composite Frames and Joints Prof. Shiming Chen 2013, May
OBJECTIVE/SCOPE To define and introduce beam-to-column joints; To introduce composite Frames; To describe their behavior; Summary of Configuration Detailing of joints
OBJECTIVE/SCOPE • To define and introduce beam-to-column joints; • To introduce composite Frames; • To describe their behavior; • Summary of Configuration Detailing of joints
8.1 Introduction A continuous beam in a building may be interrupted by its supporting internal columns;and these members are usually part of a framed structure.By definition,composite frame is a framed structure in which some or all of the elements are composite members and most of the remainder are structural steel members. Composite joint is a joint between a composite member and another composite,steel,or reinforced concrete member,in which reinforcement is taken into account in design for the resistance and the stiffness of the joint
8.1 Introduction • A continuous beam in a building may be interrupted by its supporting internal columns; and these members are usually part of a framed structure. By definition, composite frame is a framed structure in which some or all of the elements are composite members and most of the remainder are structural steel members. • Composite joint is a joint between a composite member and another composite, steel, or reinforced concrete member, in which reinforcement is taken into account in design for the resistance and the stiffness of the joint
The type of beam-to-column joints used influences the global analysis of all the members in their vicinity. Beam-to-column joints are classified both by stiffness and by strength.The categories are: For stiffness:rigid,semi-rigid,and nominally pinned; > For strength:full-strength,partial-strength,and nominally pinned
The type of beam-to-column joints used influences the global analysis of all the members in their vicinity. Beam-to-column joints are classified both by stiffness and by strength. The categories are: For stiffness: rigid, semi-rigid, and nominally pinned; For strength: full-strength, partial-strength, and nominally pinned
Composite flush end plate connections Flush end plate connection: One popular types used in construction,in which the end plate is usually welded to the beam before being bolted to the column section on-site. Connections to concrete-filled tubular sections External Diaphragm type Internal Diaphragm connections Diaphragm Steel Steel Beam Beam Square CFT Column Circular CFT Column
Composite flush end plate connections Flush end plate connection: One popular types used in construction, in which the end plate is usually welded to the beam before being bolted to the column section on-site. Connections to concrete-filled tubular sections Diaphragm type connections
Lateral Load Resisting Systems four classical lateral load resisting systems for multistory building frames.They are the (1)core braced system, (2)moment-truss system, X (3)outrigger and belt system,and (4)tube system. .Simple steel framing -Composite slab Floor Plan Composite slab Core walls一 -Simple connection core braced system Exterior steel column Corbel-
four classical lateral load resisting systems for multistory building frames. They are the (1) core braced system, (2) moment–truss system, (3) outrigger and belt system, and (4) tube system. Lateral Load Resisting Systems core braced system
Moment connection typical moment-truss system Moment frames Knee bracing X orK bracing Moment connection (al typical Moment frames (a)Moment frame with internal Concrete braced trusses walls (b)Moment frame with internal core walls. b】
(a) Moment frame with internal braced trusses. (b) Moment frame with internal core walls. moment–truss system
Moment-truss frame Moment-Truss Systems Sway characteristics of rigid braced,simple braced,and rigid unbraced frames frame Simple connection 10 15 20 Lateral defection(cm) Moment frame nteracting forces Braced Behavior of frames subjected to lateral load: (a)independent behavior, (b)interactive behavior
Moment–Truss Systems Sway characteristics of rigid braced, simple braced, and rigid unbraced frames Behavior of frames subjected to lateral load: (a) independent behavior, (b) interactive behavior
Steel-Concrete Composite Systems For composite frames resisting gravity load only,the beam- to-column connections behave as they do when pinned before the placement of concrete. Composite action in the joint:based on the tensile forces in the rebars that act with the balancing compression forces transmitted by the lower portion of the steel section that a flushed end plate bolted a bottom angle with bears against the to the column flange double web cleats column flange to form a couple
Steel–Concrete Composite Systems For composite frames resisting gravity load only, the beamto-column connections behave as they do when pinned before the placement of concrete. a flushed end plate bolted to the column flange a bottom angle with double web cleats Composite action in the joint: based on the tensile forces in the rebars that act with the balancing compression forces transmitted by the lower portion of the steel section that bears against the column flange to form a couple
Transferring of moment through slab reinforcement U bars at perimeter columns. 2150 Projection≥0.2L (a)Connection detail (b)Reinforcement detail U bars Effective breadth of slab≤6D3at edge columns
(a) Connection detail (b) Reinforcement detail Transferring of moment through slab reinforcement at perimeter columns