BLOG BRIDGE INSIGHT

## Do you know about the methods of Seismic Analysis and their application in midas Civil?

Seismic analysis is needed to investigate the response of a structure to earthquakes and design the structures accordingly. Several types of methods may be used for the seismic analysis of bridges such as static seismic method, response spectrum method, pushover analysis, and time history analysis. Midas Civil software provides all these sophisticated techniques to be used in an intuitive way which can accelerate the seismic design of bridges manyfold.

Through this eBook, we will learn about various concepts of seismic analysis of bridges and how we can implement the same in Midas Civil. Furthermore, some important considerations and practical aspects of modeling are discussed regarding the seismic analysis of curved bridges and cable bridges.

Key Points

1. What is Seismic Analysis?
- Seismic Design Process
Most of the structures need to be designed for earthquake or seismic events by performing
seismic analysis which could be a simple static seismic load or a dynamic analysis in which
ground acceleration is applied to the structure and the response is captured.

2. Key Concepts/Methods of Seiemic Analysis

02-1. Equivalent Static Seismic Force Method
02-2. Modal Analysis
02-3. Response Spectrum Analysis

* Seismic Load by Response Spectrum Analysis
Step1. Setup Eigenvalue analysis
Step2. Define the Response Spectrum function based on the code
Step3. Select the method used to combine the results for different mode

02-4. Pushover Analysis
- Pushover Global Control
- Pushover Hinge Properties and Assignment

02-5. Time History Analysis
- Modal Method
- Direct Integration method

3. Application in midas Civil
- 03-1. Curved Bridges
- 03-2. Cable Bridges
- Axial Stiffness of Cable - Ernst equation
- Geometric Stiffness of Cable

Seismic analysis is crucial to investigate the response of a structure to earthquakes and design
the structures accordingly. Different methods of analysis can be adopted to assess the seismic
behavior starting from a basic linear static method to rather comprehensive and sophisticated
techniques like pushover analysis and non-linear time history analysis which are briefly
discussed in this article. The application of various seismic methods using FEM Software(midas
Civil) is also described. In general, the designer can adapt the seismic method for a given
structure using code guidelines to ensure safe design while maintaining the cost savings.