IS 1893:2016 Part 1 is the Indian Standard (BIS) for criteria for earthquake resistant design of structures - general provisions and buildings. This part of IS 1893 provides the general principles and criteria for earthquake-resistant design of structures, with a specific focus on buildings. It outlines methodologies for determining seismic base shear using equivalent static and dynamic analysis, its distribution along the building height, and the evaluation of storey drift to ensure life safety during seismic events.
Provides general criteria for earthquake resistant design of buildings and structures, including seismic zoning, importance factors, and design procedures.
Zone factors, importance factor, response reduction R, time period formulas, design Ah and storey drift.
| Reference | Value | Clause |
|---|---|---|
| Seismic Zone II — zone factor Z | 0.10 | Cl. 6.4.2 (Table 3) |
| Seismic Zone III — Z | 0.16 | Cl. 6.4.2 (Table 3) |
| Seismic Zone IV — Z | 0.24 | Cl. 6.4.2 (Table 3) |
| Seismic Zone V — Z | 0.36 | Cl. 6.4.2 (Table 3) |
| Importance factor I — ordinary buildings | 1.0 | Cl. 7.2.3 (Table 8) |
| Importance factor I — important / community service | 1.2 | Cl. 7.2.3 (Table 8) |
| Importance factor I — emergency / hospital / lifeline | 1.5 | Cl. 7.2.3 (Table 8) |
| Response reduction R — OMRF (RC) | 3.0 | Cl. 7.2.6 (Table 9) |
| Response reduction R — SMRF (RC) | 5.0 | Cl. 7.2.6 (Table 9) |
| Response reduction R — RC shear wall building | 4.0 (ordinary) / 5.0 (ductile) | Cl. 7.2.6 (Table 9) |
| Response reduction R — steel SMF | 5.0 | Cl. 7.2.6 (Table 9) |
| Response reduction R — steel CBF / EBF | 4.0 / 5.0 | Cl. 7.2.6 (Table 9) |
| Time period Ta — RC moment frame | Ta = 0.075 h^0.75 | Cl. 7.6.2 (a) |
| Time period Ta — steel moment frame | Ta = 0.080 h^0.75 | Cl. 7.6.2 (b) |
| Time period Ta — all other (with infill) | Ta = 0.09 h / √d | Cl. 7.6.2 (c) |
| Sa/g — Type I (rocky/hard) plateau (0.10–0.40 s) | 2.50 | Cl. 6.4.2 (Fig. 2 / Eq.) |
| Sa/g — Type II (medium) plateau | 2.50 (0.10–0.55 s) | Cl. 6.4.2 (Fig. 2 / Eq.) |
| Sa/g — Type III (soft) plateau | 2.50 (0.10–0.67 s) | Cl. 6.4.2 (Fig. 2 / Eq.) |
| Design horizontal seismic coefficient Ah | Ah = (Z/2) · (Sa/g) · (I/R) | Cl. 6.4.2 |
| Min design base shear ratio (VB/W) — Zone V (low T, hard soil) | Use min Ah floor — refer Cl. 7.2.2 | Cl. 7.2.2 |
| Drift limit — storey | 0.004 × storey height (h_si) | Cl. 7.11.1 |
| Vertical seismic coefficient Av | (2/3) Ah | Cl. 6.4.5 |
| Damping ratio — RC / steel buildings (default) | 5 % / 2 % | Cl. 7.2.4 |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
IS 1893 Part 1:2016 governs earthquake resistant design of buildings and general structures in India. Every building above ground in Seismic Zone II (Z=0.10) through Zone V (Z=0.36) must apply this code for lateral load estimation — residential G+1 and above, commercial construction, hospitals, schools, and essentially all new construction.
IS 1893 establishes the *lateral force demand*. Detailing for ductile behaviour follows separate codes:
Per Clause 7 of IS 1893 Part 1:2016:
Most residential and commercial buildings up to G+15 in Zones III-IV qualify for Equivalent Static. Once you're above G+15 or in Zone V, plan for RSA from the start — structural software (STAAD, ETABS, SAP) handles it routinely.
Problem: 5-storey (G+4) RC residential building, total height h = 15 m, in Hyderabad (Zone II). Ordinary moment-resisting frame (OMRF). Medium soil (Type II). Estimate design base shear.
Step 1 — Zone factor from Annex E: Hyderabad = Zone II → Z = 0.10
Step 2 — Importance factor per Table 8: Residential (ordinary occupancy) → I = 1.0 (Would be 1.2 for hospital/school/fire-station, 1.5 for critical facilities like nuclear plant.)
Step 3 — Response reduction factor per Table 9: Ordinary RC MRF → R = 3.0 (For Special MRF with full IS 13920 ductile detailing, R = 5. Using R = 5 without the detailing is non-compliant.)
Step 4 — Fundamental period per Clause 7.6.2 for RC MRF without infills: T_a = 0.075 × h^0.75 = 0.075 × 15^0.75 = 0.57 s (With brick infills: T_a = 0.09 × h / √d_x where d_x is plan dimension along shake direction.)
Step 5 — Spectral acceleration Sa/g from Figure 2 for Type II soil (medium), T_a = 0.57 s: Sa/g ≈ 2.5 (between 0.55 and 4.0 s, flat region)
Step 6 — Design horizontal acceleration coefficient per Clause 6.4.2: A_h = (Z/2) × (I/R) × (Sa/g) = (0.10/2) × (1.0/3) × 2.5 = 0.0417
Step 7 — Design base shear per Clause 7.5.3: V_B = A_h × W, where W = seismic weight per Clause 7.3 (DL + imposed-load-per-7.3.2) For W ≈ 12,000 kN (typical 5-storey RC building of ~2000 m² plan): V_B = 0.0417 × 12,000 = 500 kN at base
Step 8 — Distribute to floors per Clause 7.7.1: F_i = V_B × (W_i × h_i²) / Σ(W_j × h_j²)
Step 9 — Check storey drift per Clause 7.11.1: drift ratio ≤ 0.004 under factored loads (not unfactored). For h = 15 m, max drift = 60 mm across all storeys — tight limit that many ordinary frames fail at lower levels.
1. Wrong zone for the actual project site. Some engineers use the "nearest major city" zone when the project is in a border district that falls in a different zone. Always use Annex E (or the IS 1893 Part 1 zone map at Figure 1) for the exact district or tehsil.
2. Missing the importance factor. Schools, hospitals, fire stations, public assembly buildings → I = 1.2 minimum per Table 8. Critical facilities (nuclear, LNG) → I = 1.5. Using I = 1.0 for a school is non-compliant and professionally risky.
3. Wrong response reduction factor. R = 5 applies only to Special Moment-Resisting Frames — which requires full IS 13920 ductile detailing (135° hooks, confining hoops at d/4 in plastic hinge zones, column splice only in middle half, strong-column-weak-beam check). Using R = 5 without IS 13920 compliance is unconservative by ~40%. For ordinary detailing, use R = 3.
4. Ignoring storey drift check. Storey drift ratio must be ≤ 0.004 under factored loads per Clause 7.11.1. Limits are tight — many designs pass member strength checks but fail drift at lower storeys where axial loads are highest.
5. Assuming rigid diaphragm for irregular plans. Plans with aspect ratio > 3:1 or significant L/T shape offsets should check whether the rigid diaphragm assumption is valid (Clause 6.3.2). Use semi-rigid or flexible diaphragm for highly irregular layouts; rigid diaphragm over-stiffens some frames and under-stiffens others.
IS 1893 Part 1:2016 superseded the 2002 edition with major revisions — tighter response reduction factors, explicit drift limits under factored loads, more stringent requirements for irregular buildings, and clearer guidance on soft-storey detection. Many mid-rise buildings designed per IS 1893:2002 would fail today's IS 1893:2016 drift check at lower storeys.
For design review or peer review, always verify which edition your structural consultant used. Some consultants are slow to update reference libraries. BIS has issued amendments (A1 in 2018, A2 in 2022 clarifying response spectrum for deep soil sites); check for current amendments before design freeze.
For seismic-critical projects (hospitals in Zone IV/V, schools designated as shelters, buildings above 60 m in Zone V), the 2016 edition is still more conservative than many international equivalents — but supplement with site-specific response spectrum analysis where the seismo-tectonic setting warrants (near active fault lines, soft-soil basins like Delhi-Meerut plains or coastal sediment zones).
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Seismic Zone Factor (Z) / MCEr PGA equivalent | Z = 0.36 for Zone V (highest seismic zone) | Mapped Ss and S1 values up to ~2.0g and 0.8g (MCEr spectral acceleration for short and 1-second period respectively), which can translate to PGA up to ~0.5g or more in high seismic regions. | ASCE 7-16 |
| Soil Classification Types | Type I (Rock/Hard), Type II (Medium), Type III (Soft) | Site Class A (Hard Rock) to F (Special Soils) | ASCE 7-16 |
| Response Reduction Factor (R) for Special RC Moment Resisting Frame (SMRF) | R = 5 | R = 8 for Special Reinforced Concrete Moment Frames | ASCE 7-16 |
| Importance Factor (I / Ie) for Essential Facilities (e.g., Hospitals) | I = 1.5 | Ie = 1.5 | ASCE 7-16 |
| Minimum Cumulative Mass Participation for Dynamic Analysis | At least 90% of the total seismic mass | At least 90% of the total seismic mass | ASCE 7-16 / EN 1998-1:2004 |
| Basic value of Factor for site amplification (similar to Fa, Fv) | Varies based on soil type and time period (e.g. constant 2.5 for T between 0.1 and Ta for Type II soil) | Site Coefficient Fa (short periods) and Fv (long periods), varying with Site Class and mapped spectral accelerations | ASCE 7-16 |