Locations shear walls to stiffen usually added at

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Unformatted text preview: TIFF AND ARE SUBJECT TO TORSIONAL BENDING (TWISTING) BY SIDEWARD FORCES • FRAMES AREN’T moment connections Shear diaphragms may be used at floors DIAGONAL BRACING SHEAR DIAPHRAGMS and some vertical locations (shear walls) to stiffen • USUALLY ADDED AT CORNERS frame! • FLOORS AND SHEAR WALLS !! LIGHTEST SOLUTION PLYWOOD SHEETS OR • •STEEL CABLES OR RODS Monday, March 18, 13 • REINFORCED CONCRETE MOMENT-RESISTING JOINTS Moment-resisting joints may be used instead NSTEAD OF SHEAR JOINTS • Iof shear joints to stiffen frame •BULKY; REQUIRE OVERSIZEand expensive! Moment joints more complex BEAMS + COLUMNS CONNECTIONS TYPES OF CONNECTIONS • PINS: ROTATION BUT NOT TRANSLATION • MOMENT CONNECTIONS: NO TRANSLATION OR ROTATION • ROLLERS: ONLY TRANSLATION Monday, March 18, 13 • WE USE BOTH FIXED + PINNED CONNECTIONS BECAUSE WE DO NOT WANT TO IMPART BENDING LOADS TO FOUNDATIONS (CONSTANT MOVEMENT WILL WEAKEN SOIL) • ALSO BECAUSE PRE-COMPUTERS WE COULD NEVER FULLY CALCULATE REACTIONS SO WE USED TRIAL + ERROR MULTIPLE FRAMES • MULTIPLE FRAMES HELPES RESIST UPLIFTING + RACKING BY SPREADING THE LATERAL FORCE TO SEVERAL CONNECTIONS AND PROVIDING REACTIONS WITH LARGER MOMENT ARMS • TABLE-LEG PRINCIPLE: ALLOWS WEAK CONNECTIONS TO WORK SYNERGETIC-ALLY TO RESIST WIND FORCES ALONG THE LENGTH OF A STRUCTURE Monday, March 18, 13 DETERMINACY VS. INDETERMINACY + FRAME SYNERGY • DETERMINATE STRUCTURE: A STRUCTURE WHOSE CONDITIONS CAN BE EASILY FIGURED ALGEBRAICALLY (M = 0) • INDETERMINATE STRUCTURE: CANNOT BE SOLVE ALGEBRAICALLY (USUALLY BECAUSE FIXED CONNECTIONS OFFER THE CAPACITY TAKE TAKE MOMENT STRESS) • “MOMENT ATTRACTION”: BENDING MOMENT WILL TEND TO COLLECT AROUND THE STIFFEST CONNECTIONS IN A FRAME • AS THE COLUMNS GET RELATIVELY STIFFER, WE TEND TO REDUCE THE MAXIMUM MOMENT AT THE BEAM’S CENTER • IF WE ADD A HINGE TO THE CENTER, THE MOMENT CURVE REVERSES Monday, March 18, 13 FRAMES: WOOD COMPONENTS • TIMBERS HAVE BEEN USED AS SPANNING ELEMENTS FOR MODERATELY-SIZED BUILDINGS WHERE CRAFT IS VALUED HEAVY TIMBER FOUNDATIONS HEAVY TIMBER COLUMNS HEAVY TIMBER FLOOR IF INTERFACED WITH SOIL, MUST BE ANY FLOOR CAPABLE OF 6-10 FOOT TREATED WITH LUMBER STEEL HARDWARE FOR CONNECTS SPANS, USUALLY WITH 2” DECKING HEAVY TIMBER ROOF HEAVY TIMBER WALLS PRIMARY STRUCTURE MAY BE CARRY DEAD LOAD, MUST HOLD TRUSSES, SECONDARY IS DECKING Monday, March 18, 13 BUILT FROM DIMENSIONAL LUMBER + LATERAL LOADS W INFILL OR CLAD FRAMES: STEEL EVOLVED FROM IRON TECHNOLOGY AND USED IN EARLY 20TH CENTURY, SEEN AS NEAR PERFECT STRUCTURAL FRAME MATERIAL PROS CONS 1. HIGH STRENGTH, STIFFNESS + 1. PROTECTED AGAINST DENSITY CORROSION + FIRE 2. SIMPLE INSTALL (FAST + EASY) 2. UNSTABLE: HIGH EXPANSION 3. EASILY + WIDELY RECYCLABLE 3. REQUIRES HIGH ENERGY 4. FABRICATION IS SPECIALIZED + EXPENSIVE Monday, March 18, 13 BASIC COMPONENTS • PRIMARY STRUCTURE: GIRDER • SECONDARY STRUCTURE: BEAM • STEEL COLUMN • CURTAIN WALL FRAMES: STEEL COMPONENTS STEEL FRAME FOUNDATIONS STEEL FRAME FLOOR GENERALLY REINFORCED CONCRETE VERTICAL + HORIZONTAL: GIRDERS, COMPOSITE DECK OR PRECAST FOOTINGS + CONNECTIONS OPEN WEB JOISTS, TRUSSES PLANKS, BOTH WITH CONCRETE STEEL FRAME ROOF CURTAIN WALLS STEEL DECK + PRECAST PLANKS WITH PANELIZED WALL SEGMENTS STEEL FRAME CONNECTIONS AISC1: RESIST V + M VR, INSULATION, WB + CLADDING Monday, March 18, 13 COLUMNS + BEAMS BETWEEN COLUMNS; CLADDING AISC2: RESIST V AISC3: R...
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This document was uploaded on 03/15/2014 for the course ARCH 242 at California State Polytechnic University.

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