N E P A L N A T I O N A L B U I L D I N G C O D E

1 105:2077 N E P A L N A T I O N A L B U I L D I N G C O D E NBC: 105: 2020 ( ) SEISMIC DESIGN OF BUILDINGS IN NEPAL , , i Contents 1 Title, Scope, Definitions and Notations .. 1 Title .. 1 Scope .. 1 Definitions .. 1 Notations .. 5 Units .. 8 2 General 9 PERFORMANCE REQUIREMENTS AND VERIFICATION .. 9 Life 9 Damage Limitation .. 9 VERIFICATION: .. 9 GENERAL GUIDELINES FOR ARRANGEMENT OF BUILDING STRUCTURAL SYSTEMS.

2 11 Structural simplicity .. 11 Uniformity, symmetry and redundancy .. 11 Adequate resistance and stiffness .. 12 Diaphragm action .. 12 Adequate foundation .. 13 RESPONSE TO EARTHQUAKE GROUND MOTION .. 13 Ground Motion .. 13 Response of Structure .. 13 Soil-structure Interaction .. 14 CAPACITY DESIGN .. 14 Potential Plastic Zones .. 14 Level of Detailing .. 14 Over strength Actions .. 14 ii BASIC ASSUMPTIONS .. 14 3 Scope of Analysis .. 16 STRUCTURAL ANALYSIS METHODS .. 16 APPLICABILITY OF ANALYSIS METHODS .. 16 Equivalent Static Method (ESM).

3 16 Modal Response Spectrum Method (MRSM) .. 16 Elastic Time History Analysis .. 17 Non-linear Methods .. 17 APPLICATION OF SEISMIC 17 EFFECTIVE STIFFNESS OF CRACKED SECTIONS .. 17 DESIGN METHODS .. 18 LOAD COMBINATIONS FOR LIMIT STATE METHOD .. 18 Load Combinations for Parallel Systems .. 18 Load Combinations for Non- Parallel Systems .. 18 4 Seismic Hazard .. 19 ELASTIC SITE SPECTRA FOR HORIZONTAL LOADING .. 19 Elastic site spectra .. 19 Spectral Shape Factor, Ch (T) .. 19 Site Subsoil Category .. 21 Seismic Zoning Factor (Z).

4 23 Importance Classes and Importance Factor (I) .. 26 ELASTIC SITE SPECTRA FOR SERVICEABILITY LIMIT STATE .. 26 ELASTIC SITE SPECTRA FOR VERTICAL LOADING .. 27 5 Dynamic Characteristics of Structures .. 28 PERIODS OF VIBRATION .. 28 Rayleigh Method .. 28 Empirical Equations .. 28 iii Amplification of Approximate Period .. 29 SEISMIC WEIGHT .. 29 DUCTILITY FACTOR .. 29 Ultimate limit state .. 29 Serviceability limit state .. 30 OVERSTRENGTH FACTOR .. 30 Ultimate limit state .. 30 Serviceability limit state .. 30 STRUCTURAL IRREGULARITY.

5 31 Vertical Irregularity .. 31 Plan Irregularity .. 32 DRIFTS AND DISPLACEMENTS .. 34 Determination of Design Horizontal Deflections .. 34 Building Separations .. 34 Inter-Story Deflections .. 35 ACCIDENTAL ECCENTRICITY .. 35 6 Equivalent Static Method .. 36 HORIZONTAL BASE SHEAR COEFFICIENT .. 36 Ultimate Limit State .. 36 Serviceability Limit State .. 36 HORIZONTAL SEISMIC BASE SHEAR .. 36 VERTICAL DISTRIBUTION OF SEISMIC 37 POINTS OF APPLICATION OF EQUIVALENT STATIC FORCES .. 37 7 Modal Response Spectrum Method.

6 38 ULTIMATE LIMIT STATE .. 38 CALCULATION OF BASE SHEAR FORCE FOR EACH MODE .. 38 NUMBER OF MODES TO BE CONSIDERED .. 39 iv COMBINATION OF MODAL EFFECTS .. 39 SCALE FACTOR FOR DESIGN VALUES OF THE COMBINED RESPONSE .. 39 8 Elastic Time History Analysis .. 40 Structural Modeling Requirements .. 40 Ground Motions .. 40 Evaluation of response quantities .. 40 9 Non-linear Static and Dynamic Analysis .. 42 GENERAL .. 42 NON-LINEAR STATIC 42 Modeling and Analysis .. 42 Load pattern .. 42 Control node .. 42 Capacity curve.

7 42 Target displacement .. 42 NON-LINEAR TIME HISTORY ANALYSIS .. 43 Structural Modeling Requirements .. 43 Ground Motions .. 44 Evaluation of response quantities .. 45 10 Parts and Components .. 47 GENERAL .. 47 SERVICE CUT-OFFS .. 47 DESIGN SEISMIC FORCE .. 47 Component Amplification Factor .. 48 Component Ductility Factor .. 48 Component Importance Factor .. 49 OTHER REQUIREMENTS .. 49 v ANNEX A: DESIGN AND DETAILING OF reinforced concrete STRUCTURES FOR EARTHQUAKE LOADS .. 51 1 General .. 51 Definitions .. 51 Notations.

8 52 Units .. 55 2 Materials .. 56 Grade of Material .. 56 Expected Material Strength .. 56 3 Location of Plastic Hinges .. 57 4 moment Resisting Frames .. 58 58 Dimensional Limits .. 58 Longitudinal Reinforcement .. 58 Transverse Reinforcement .. 58 61 Dimensional Limits .. 62 Longitudinal Reinforcement .. 62 Transverse Reinforcement .. 62 Special Confining Reinforcement .. 65 BEAM-COLUMN JOINTS .. 68 Design of Beam-Column Joint for Distortional 68 Anchorage of Beam Longitudinal bars .. 70 Development Length of Straight Deformed bars in 72 Column-Beam moment Capacity Ratio.

9 72 Splicing of bars .. 72 Lap Splices .. 72 vi 5 SHEAR WALLS .. 74 General Requirements .. 74 Design for Shear Force .. 74 Boundary 76 Design for Axial Force and Bending moment .. 76 Coupling Beams .. 77 Openings in Walls .. 77 Construction Joints .. 78 Anchorage of Longitudinal Bars .. 79 Splicing of Bars .. 79 ANNEX B: DESIGN AND DETAILING OF STEEL STRUCTURES FOR EARTHQUAKE LOADS .. 80 1 General .. 80 Definitions .. 80 Notations .. 83 Units .. 84 2 Materials .. 85 Grade of Material .. 85 Expected Material Strength.

10 85 Section Requirements .. 85 3 Connections .. 86 Bolted and Welded connections .. 86 Column Splices .. 86 Column Bases .. 87 4 Location of Plastic Hinges .. 88 5 moment Resisting Frames .. 89 89 vii 89 Beam to Column Connections .. 89 Column-Beam moment Capacity Ratio .. 91 6 Frames with Concentric 92 Concentric Braces .. 92 Slenderness ratio .. 92 Placement of braces .. 92 Built-up Member braces .. 92 Brace Connection .. 93 Beams and Columns .. 93 7 Frames with Eccentric Braces .. 94 Seismic Links .. 94 Link Section Limitations.