Model Code Final draft. Volume 2

Transcription

1 Model Code 2010 Final draft Volume 2 April 2012

2 Volume Contents Preface Contributors Notations Acronyms iii iv xx xxxvi 7 Design Conceptual design General Methodology Input Activities The role of expertise, insight and tools Stmctural Concept and Basis for Design Structural analysis and dimensioning General Structural modelling General Geometric imperfections Structural geometry Calculation methods Dimensioning values Concrete Reinforcing steel Prestressing steel Analysis of structural effects of timedependent behaviour of concrete General Levels of refinement of the analysis Probabilistic and detenninistic approach Prediction models for concrete and significance of the analysis Timedependent analysis based on aging linear viscoelasticity Constitutive laws in aging linear viscoelasticity Simplified approaches for timedependent analysis Effective homogeneous concrete structures with rigid or stressindependent yielding of restraints Effective homogeneous concrete structures with additional steel structural elements Approximate algebraic formulation for the constitutive relation: ageadjusted effective modulus (AAEM) method General method Verification of structural safety (ULS) for predominantly static loading General Bending with and without axial force Beams, columns and slabs Shells 43 2 xiii

3 7.3.3 Shear General Members without shear reinforcement Members with shear reinforcement Hollow core slabs Shear between web and flanges of Tsections Shear at the interface between concrete cast at different times Torsion Punching General Design shear force, shearresisting effective depth and control perimeter Punching shear strength Calculation of rotations around the supported area Punching shear resistance outside the zones with shear reinforcement or shearheads Integrity reinforcement Design with stress fields and strutandtie models General Struts Ties Nodes Compression members Stability of compressed members in general Biaxial eccentricities and outofplane buckling Lateral instability ofbeams D Solids Stress limit requirements Ductility requirements Verification of structural safety (ULS) for nonstatic loading Fatigue design Scope Analysis of stresses in reinforced and prestressed members under fatigue loading Level I of Approximation: the simplified procedure Level II of Approximation: verification by means of a single load level Level III of Approximation: verification by means of a spectrum of load levels Shear design Increased deflections under fatigue loading in the SLS Impact and explosion General remarks Determination of design loads Dimensioning for overall stresses Structural detailing Seismic design Format of the verifications Determination of seismic action effects through analysis ULS verifications of inelastic flexural deformations Cyclic plastic chord rotation capacity Cyclic shear resistance at the ULS in members with shear reinforcement 128 xiv Volume 2

4 ULS verification of joints between horizontal and vertical elements SLS verifications of flexural deformations Verification of structural safety (ULS) for extreme thermal conditions Fire design Introduction Fire design principles Calculation method Structural elements Compartmentation Cryogenic design General Design loads to be regarded in the design of structures for refrigerated liquefied gases Failure mechanisms to be regarded in the design of structures for storing refrigerated liquefied gases Concrete material properties under cryogenic conditions Verification of serviceability (SLS) ofrc and PC structures Requirements Design criteria Stress limitation Tensile stresses in the concrete Limit state of decompression Compressive stresses in the concrete Steel stresses Limit state of cracking Requirements Design criteria versus cracking Limitation of crack width Calculation of crack width in reinforced concrete members Calculation of crack width in prestressed concrete members Control of cracking without calculation Limit states of deformation General Deformations due to bending with or without axial force Vibrations General Vibrational behaviour Verification of serviceability limit state by numerical simulation Fracture mechanicsbased models Tension stiffeningbased models Verification of safety and serviceability of FRC structures Classification Design principles Verification of safety (ULS) Bending and/or axial compression in linear members Shear in beams Torsion in beams Walls Slabs 194 Volume 2 XV

5 uncracked Volume Verification of serviceability (SLS) Stress limitation Crack width in members with conventional reinforcement Minimum reinforcement for crack control Verification of limit states associated with durability General Carbonation induced corrosion concrete Probabilistic safety format Partial safety factor format Deemedtosatisfy design Avoidanceofdeterioration design Chloride induced corrosion uncracked concrete Probabilistic safety format Partial safety factor format Deemedtosatisfy design Avoidanceofdeterioration design Influence of cracks upon reinforcement corrosion Risk of depassivation with respect to prestressed steel Freeze/thaw attack Probabilistic safety format Partial safety factor format Deemedtosatisfy approach Avoidanceofdeterioration method Chemical attack Acid attack Sulphate attack Alkaliaggregate reactions Probabilistic safety format Partial safety factor format Deemedtosatisfy approach Avoidanceofdeterioration approach Delayed ettringite formation Probabilistic safety format Partial safety factor format Deemedtosatisfy approach Avoidanceofdeterioration approach Verification of robustness General Specific methods to improve robustness by structural measures Robustness by creating an alternative loading path Capacity design Verification of sustainability Impact on environment General Verification Impact on society General Verification 227 xvi 2

6 structural Volume 7.11 Verifications assisted by numerical simulations Purpose Methods of numerical simulation Numerical model Finite element method Material models Validation of numerical models Safety formats for nonlinear analysis General Probabilistic method Global resistance methods Partial factor method Resistance parameter identification 7.12 Verification assisted by testing Scope Definition Aims of verification assisted by testing Requirements Planning Calculation modellimit states Information on basic variables Number of specimens Scale effects Actions Origin of specimens Testing conditions and measurements Basic and nominal variables Actions Deformation Laboratoiy report behaviour Statistical analysis of test results Estimation of the unknown coefficients D Characteristic value Verification procedure Design values Verification 7.13 Detailing Basic principles Positioning ofreinforcement General Cover of reinforcement Minimum bar spacing Forms and bends Anchorage Lapped joints Deviations and curvatures Prestressed structures Anchorage of prestressing wires and strands Bearings and joints xvii

7 prestressing Volume Structural members Unreinforced structural members Beams and Tbeams Slabs Compression members Special aspects of precast concrete elements and composite structural members General Bearings Mortar joints Loop connections Transverse stresses in the anchorage zone of prestressed tendons Verification of anchorages in concrete Construction General Execution management Assumptions Documentation Quality management Reinforcing steel works Transportation and storage Identification Cutting and bending Welding Joints Assembly and placing of the reinforcement Construction documents reinforcement Prestressing works General Packaging, transportation, storage and handling ofmaterials and components Prestressing works for posttensioning tendons Installation of tendons Tensioning operations Grouting of prestressing ducts Prestressing works for pretensioning tendons Installation of tendons Tensioning operations Sealing Replacement of tendons Construction documents Falsework and formwork Concreting Specification of concrete Placing and compaction Curing Execution with precast concrete elements Geometrical tolerances 298 xviii 2

8 9 Conservation General Conservation strategies and tactics General Strategy using proactive conservation measures Condition based conservation Time dependent conservation Strategy using reactive conservation measures Situations where conservation measures are not feasible Conservation management Throughlife conservation process Conservation Plan Condition survey Condition survey and monitoring activities Locations for surveys and monitoring activities Tools and techniques for surveys and monitoring Gathering data for Condition Control purposes General flow of condition survey process Condition assessment Identification of deterioration mechanisms and prediction of damage Identification of deterioration mechanism Factors influencing deterioration Determination of deterioration level and rate Condition evaluation and decisionmaking General Threshold levels for deterioration of material and/or structural performance Judgment criteria Selection of interventions Interventions Maintenance interventions Preventative interventions Remedial interventions Rebuild, reconstruction and replacement Strengthening or upgrading interventions Other activities and measures Execution of interventions Recording Dismantlement General Preparing dismantlement General Consequence class of the structure Structural analysis for dismantlement Investigation of potential contamination Waste disposal concept Preparation report Safety and health provisions 331 Volume 2 xix