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UNDERSTANDING the LOAD CARRYING SYSTEM of BUILDINGS alias STRUCTURE SYSTEM •Method of approach to understanding •Collection of interrelated elements •Various aspects of elements and relationships •Problems related to the whole system STRUCTURE •Abstract notion describing interrelationship of elements •Many different representations (verbal, graphical, mathematical). •Multiple structures in a system. MY FAMILY SYSTEM Mother Father Foster mother Sister Brother in Law Brother Me Wife Sister in Law Nephew Son Daughter Son Daughter Niece in Law in Law Grandson Granddaughter STRUCTURE of MARRIAGES MATHEMATICAL REPRESENTATION Foster Sister Daughter Mother Mother Wif e Daughter Sister in Law in Law Father 1 1 0 0 0 0 0 Me 0 0 1 0 0 0 0 Son 0 0 0 0 0 0 1 Son in Law 0 0 0 1 0 0 0 Brother 0 0 0 0 0 1 0 Brother in Law 0 0 0 0 1 0 0 PARENTAGE STRUCTURE GRAPHICAL REPRESENTATION Mother Father Foster mother Sister Brother in Law Brother Me Wife Sister in Law Nephew Son Daughter Son Daughter Niece in Law in Law Grandson Granddaughter A SIMPLE BUILDING PLAN Secretary Boss Room 1 Reception Hall Corridor Room 4 Room 3 Room 2 Exterior CIRCULATION STRUCTURE Room 4 Room 1 Room 3 Hall Corridor Room 2 Boss Reception Exterior Secretary WHY BUILDINGS? •Meso-environment (thermal, acoustic, light) •Security (predators, pests, enemies, etc.) PROBLEMS in BUILDINGS • Problems and factors • Nearly all elements involved • Problem specific structures HUMAN FACTORS • Psychological (spatial perception, spatial cognition) • Physiological (thermal comfort) • Social (spatial layout) • Cultural (meanings, use patterns, etc.) ENVIRONMENTAL FACTORS •Climatic (thermal, radiation, wind, rain, snow, etc.) •Economic (materials, labor, finance) •Geological (gravitation, earthquakes, materials, foundations) •Topographical (slopes, vegetation) MECHANICAL FACTORS •Mechanics (forces and motions) •Loads (gravitation, wind, earthquakes) •Foundations LOAD CARRYING SYSTEM (LCS) • Elements + connectivity structure • STRUCTURE of building • Structural problems Column 1 Column 4 Column 2 Column 3 A SIMPLE BUILDING LCS BUILDING ELEMENTS C1 C2 C3 C4 B1 B2 B3 B4 STRUCTURE of CONNECTIVITY Slab B1 B2 B3 B4 Wall 1 Wall 2 C1 C2 C3 C4 Edge connection End connection STRUCTURAL REQUIREMENTS of LCSs • Restraint (sufficient members and supports to provide for equilibrium) • Strength (sufficient material to prevent rupture) • Rigidity (sufficient resistance to deformation) • Ductility (sufficient capacity for energy absorption) COMPATIBILITY REQUIREMENTS of LCSs • Spatial layout (e.g. hotels, bearing walls) • Materials (e.g. masonry and vaults) • Services (integration of services) • Construction (e.g. bearing walls, integral forms, tower cranes) STRUCTURAL BEHAVIOR •Internal forces Load Load Internal force •Displacements/deformations •Energy storage •Language of description is mechanical. UNDERSTANDING BEHAVIOR of LCSs •Modeling of LCS •Prediction of loads •Analysis of mechanical forms •Understanding in terms of basic modes DIRECTION of PREDOMINANT LOAD •Vertical (gravitation) •Horizontal (wind) •Combination (earthquake) GEOMETRIC FORM •Dimensionality •Orientability •1D forms - rod, planar curve, spatial curve •2D forms - plane, surface, systems of 1D forms •3D forms - solid, systems of 1D and 2D forms MECHANICAL FORM •Combination of geometric form and load •Mechanical form = Oriented and loaded geometric form Load Orientation MECHANICAL FORMS (BEAM and COLUMN) Geometric Form = ROD Load Orientation Load Orientation BEAM COLUMN MECHANICAL FORMS (ARCH and CURVED BEAM) Geometric Form = PLANAR CURVE Load Load Load Orientation Load Orientation ARCH CURVED BEAM Arch Curved Beam Spatial Curved Beam MECHANICAL FORMS (SLAB and WALL) Geometric Form = PLANE Load Load Load Orientation Load Orientation WALL SLAB Slab Folded Plate MECHANICAL FORMS (SHELL) Load Shell Dome UNDERSTANDING SPECIFIC BUILDING LCS’s •Resolve hierarchy of structural problems •Determine scale of problem (overall building, breakdown of main structure, detail elements) •Resolve structure of elements •Recognize the MF of elements World Trade Towers SKYSCRAPER (overall building scale) Gravitation Wind or Earthquake GF = ROD MF = COLUMN MF = BEAM SKYSCRAPER (main structure scale) GF = PLANE GF = PLANE Gravitation Gravitation Earthquake MF = SLAB MF = WALL MF = WALL Sears Tower Axial Load Lateral SKYSCRAPER Load (detail scale) GF = ROD GF = PLANE Weight MF = COLUMN MF = BEAM Weight MF = SLAB Axial Load BEHAVIOR of the BEAM INTERNAL FORCES BENDING MOMENT SHEAR BEHAVIOR of the COLUMN Compression Tension INTERNAL FORCES COMPRESSIVE TENSILE AXIAL FORCE AXIAL FORCE BEHAVIOR of the COLUMN (BUCKLING) Load INTERNAL FORCE BENDING MOMENT DESIGN for BENDING •Provide material away from the center. •Provide the right kind of material. I beam RC beam DESIGN for SHEAR Provide diagonals Truss I beam Welding Castella beam DESIGN for COMPRESSION Provide the necessary material in axial form. AGAINST BUCKLING Provide this material away from the center. TWO BASIC PROBLEMS 1. Space enclosure. Planes of equal potential energy 2. Provision of horizontal levels. CONCLUSION •Look at a building LCS hierarchically. •Identify the predominant loading. •Identify the geometric form. •Identify the mechanical form. •Estimate the behavior.
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