Member Approaches
- Design procedure: specifications à loadings: static/dynamic/impact, long/short-term, certain/uncertain, design/construction/service stages à estimations & experienced projections à member: capacities à adequacy
- Approaches:
- Theoretical: formulations, assumptions, idealistic
- Problem understanding
- Modeling with assumptions
- Governing equations
- Criteria: like equilibrium, compatibility
- Boundary conditions: apply
- Solution derived
- Tuning & customizing to actual conditions
- Experimental: pseudo-realistic-theoretical, factory-conditions, upper bound of site conditions
- Practical: realistic actual implementation, littered with uncertainties & variations, combinations of theoretical, empirical, code-based & engineer qualitative value judgments w.r.t. criteria & expectations
- Connections:
- Capacities
- Allowance: displacements, ductility, rigidity, functionality
- Loads (moment) distribution: using stiffness ratio (continuity, assumptions), using moment distribution
- Beams:
- Kinematics: displacements, strains, essential B.C., methods: governing equation, solution by Integration, Moment-Area, Conjugate-beam, Influence line
- Kinetics: forces, stresses, natural B.C., methods: Slope deflection
- Account for level rigidity & axial stiffness of frames
- Columns:
- Basics: modified Euler buckling load (too ideal), tangent modulus (lower bound), Shanley (complicated), reduced modulus (upper bound), Perry-Robertson (BS code)
- Interactions: compression, biaxial bending, sway loads & eccentricities
- Customizing & tuning: effective length KL, moment amplification, boundary conditions/stiffness ratios
- Account for shear stiffness of frames
- Slabs:
- 2-D beam actions
- Moment factor method
- Walls:
- Shear wall: accounts for shear resistance & moment capacity
- Design for shear and moment interactions
- Ultimate:
- Strut-and-tie model: deep beams, walls, foundations
- Elastic moment distribution: continuity, stiffness ratios
- Inelastic moment re-distribution: loads > elastic capacity à excess M has to be re-distributed to surrounding members