Particular Rules for Design and Detailing

Beams require carefully detailed longitudinal and transverse reinforcement to transfer loads to supports while resisting internal forces. Minimum and maximum reinforcement areas ensure ductile behavior without reinforcement congestion. Reinforcement must be adequately anchored at supports and properly curtailed in spans to match bending moment distribution. Detailing rules specify bar spacing, cover, and bundled bar provisions to ensure proper concrete encasement and facilitate construction. Indirect support conditions (beam-on-beam) require special consideration for load transfer through reinforcement ties.

Shear reinforcement design employs a truss model accounting for concrete compression struts and transverse reinforcement tension members. The strut angle θ must be limited (cot θ = 1.0 to 2.5) to balance shear resistance with reinforcement requirements. Members without shear reinforcement are limited to concrete strength capacity. Where shear reinforcement is required, vertical or inclined stirrups provide tension resistance, with spacing controlled to prevent concrete strut failure. Reduced shear force applies for loads applied near supports, acknowledging reduced shear transfer capacity in these regions.

One-way and two-way solid slabs require flexural reinforcement distributed across their width per load distribution. Minimum and maximum reinforcement percentages apply to prevent brittle failure and control cracking. Secondary transverse reinforcement provides distribution and torsional resistance. Flat slabs with columns require concentrated reinforcement over column regions to resist concentrated loads and punching shear. Edge reinforcement prevents corner lifting at unsupported edges. Shear reinforcement becomes necessary for thicker slabs where shear stress exceeds concrete capacity, typically provided by links in two perimeters within control perimeter.

Columns require longitudinal reinforcement arranged symmetrically to resist bending and axial loads. Minimum reinforcement (0.4-1% depending on concrete strength) ensures ductility, while maximum reinforcement (6-10%) prevents congestion. Transverse reinforcement (links/hoops) provides lateral support to longitudinal bars and enhances concrete confinement. Spacing of transverse reinforcement is limited to smaller of 15 diameters of longitudinal bars or 400 mm to maintain reinforcement effectiveness. Walls require vertical and horizontal reinforcement distributed through the wall thickness to resist bending, shear, and potential cracking from shrinkage and temperature effects.

Adequate anchorage of reinforcement is fundamental to structural safety, ensuring bar forces are transferred into concrete through bond stress. Basic anchorage length depends on concrete strength, bar size, and bond characteristics. Design anchorage length adds allowance for unfavorable conditions and geometric constraints. Lap length for overlapping bars is calculated from basic length, accounting for transverse reinforcement in lap zone. Mechanical devices (couplers, welded plates) provide alternatives to traditional laps, particularly valuable in congested regions where lap space is limited. Rules differentiate tension and compression anchorage given their different bond mechanisms.

Adequate concrete cover protects reinforcement from corrosion and ensures fire resistance. Minimum cover (cmin) varies by environmental exposure class and member exposure duration. Nominal cover adds tolerance allowance (ΔCdev) to account for construction variations. For exposed surfaces, increased cover provides protection from weathering. Quality assurance procedures can reduce tolerance allowance, enabling thinner nominal covers with justified quality control. Cover requirements reflect principles in EN 206-1 durability specifications and integration with structural detailing to optimize cover placement.