Nonlinear time-history earthquake analysis for steel frames.

Area of Science:

• Structural Engineering
• Earthquake Engineering
• Computational Mechanics

Background:

• Nonlinear time-history analysis is crucial for seismic design of steel structures.
• Existing methods can be computationally intensive and complex.
• Accurate simulation of plastic behavior and second-order effects is essential.

Purpose of the Study:

• To develop a simple, efficient, and accurate method for nonlinear time-history analysis of spatial steel frames.
• To introduce a novel fiber plastic hinge approach for dynamic analysis.
• To validate the proposed method against established techniques and commercial software.

Main Methods:

• A new fiber plastic hinge method simulating one element per member.
• Incorporation of stability functions and geometric stiffness matrix for second-order effects.
• Consideration of residual stresses and shear deformation effects.
• Application of Newmark integration with Newton-Raphson iteration for solving nonlinear dynamic equations.

Main Results:

• The fiber plastic hinge method accurately captures the dynamic behavior of steel frames.
• The method is computationally efficient, minimizing time and resources.
• The proposed software (DAAD) demonstrates accuracy and reliability comparable to commercial FEA packages.
• Second-order effects and residual stresses are effectively modeled.

Conclusions:

• The proposed fiber plastic hinge method provides a robust and efficient solution for seismic analysis of steel frames.
• The DAAD software is a reliable tool for structural engineers.
• Future improvements could focus on performance-based design and analysis applications.