Seismic Analysis Tool

Professional tool for earthquake engineering and seismic design based on ASCE 7-16 standards.

Base Shear
Response Spectrum
Equivalent Lateral
Time History

Seismic Parameters

kN
Total seismic weight of building
seconds
First mode period of vibration
Ductility factor (Steel MRF: 8, Concrete: 5, Masonry: 2.5)
g
Design spectral response acceleration

Building Characteristics

Amplification due to soil conditions
Factor for vertical distribution of forces
Typical: Steel 0.02, Concrete 0.05

Response Spectrum Parameters

g
Short period spectral acceleration
g
1-second period spectral acceleration
s
Long period transition period
Site coefficient at 0.2s period
Site coefficient at 1.0s period
Damping for spectrum construction
s
Maximum period for spectrum

Equivalent Lateral Force Parameters

kN
Seismic response coefficient
m
Exponent for vertical distribution (1.0-2.0)
Factor for overturning moment calculation
%
Allowable story drift ratio

Time History Analysis Parameters

s
Analysis time step
s
Analysis duration
Record scaling factor
Damping for time history analysis

Understanding Seismic Design

Seismic analysis is essential for designing structures that can withstand earthquake forces. The analysis considers ground motion, soil conditions, and structural characteristics.

Key Insight: Effective seismic design balances strength, ductility, and energy dissipation to protect life safety during earthquakes.

Analysis Methods

Equivalent Lateral Force (ELF)

Simplified method using static forces equivalent to earthquake effects:

V = Cs × W

Where Cs is seismic coefficient and W is building weight.

Response Spectrum Analysis

Dynamic analysis using design spectrum:

Sa = f(T, ξ, Ss, S1)

Where T is period, ξ is damping, Ss and S1 are spectral accelerations.

Time History Analysis

Direct integration of equations of motion using actual or synthetic records:

mü + cẋ + kx = -müg

Most accurate but computationally intensive method.

Modal Analysis

Analysis using structure's vibration modes:

ΦTMΦü + ΦTCΦẋ + ΦTKΦx = -ΦTg

Efficient for linear elastic analysis.

Design Spectra Parameters

Parameter Description Typical Values
Ss Short period spectral acceleration 0.5g - 3.0g
S1 1-second spectral acceleration 0.2g - 1.5g
TL Long period transition 4s - 16s
Fa Site coefficient (0.2s) 0.8 - 2.5
Fv Site coefficient (1.0s) 0.8 - 3.5
SDS Design spectral acceleration (short period) 0.33g - 2.0g
SD1 Design spectral acceleration (1s period) 0.13g - 1.0g

Design Considerations

  • Ductility: Design for inelastic deformation capacity
  • Regularity: Avoid torsional irregularities and discontinuities
  • Redundancy: Provide multiple load paths for force redistribution
  • Continuity: Ensure continuous load paths from roof to foundation
  • Soil-Structure Interaction: Account for foundation flexibility
  • Nonstructural Components: Design attachments and contents for seismic forces