The new app "Eurocode 8 Pushover" is now available on Google Play. You can download it by following the link below:
The purpose of this app is to facilitate the implementation of the procedure described in Annex B of Eurocode 8, Part 1. This procedure is used to assess the so-called "target displacement". The estimation of this displacement is necessary after performing a nonlinear static analysis with lateral loading (pushover analysis) to assess the state of the structure for a given seismic action.
The figure above shows how the app looks like. The input data on the first screen include:
number of stories
ground acceleration (unit “g”)
Ground Type (from A to E)
spectrum type (Type 1 or 2)
pushover curve (units "mm" and "kN", more on that later).
The number of stories determines the number of dynamic degrees of freedom. The ground acceleration should be expressed as a function of acceleration of gravity, g, and together with the ground type and spectrum type it is used to construct the elastic response spectrum based on Eurocode 8 (2004 version).
One of the most critical steps is the correct input of the pushover results. It is necessary to pay attention to the units: "mm" for the roof displacement and "kN" for the base shear. You can copy the data directly from email or a spreadsheet app such as Google Sheets or Microsoft Excel.
The easiest way to copy the pushover data is to have them on a spreadsheet app. From there, you can copy the data and they will be automatically recognized in the correct format by the app:
If you don't have the pushover data on your Android device, you can send them over email (after copying them from a spreadsheet program). In general, it is sufficient to have the data formatted as a list in which the first item is displacement at first step, the second item is force at first step, third item is displacement at second step, fourth item is force at second step and so on. For example:
0 0
10 100
20 200
50 400
or:
0 0 10 100 20 200 50 400
are both valid.
After copying the pushover results, the next step is to paste the data by tapping the button "Paste pushover data". If successful, you should see the following message. To close the message, tap outside the popup area.
If you tap "next", you will see a table in which you need to input the mass for each degree of freedom and the normalized displacement, assuming that the displacement at roof level is equal to 1 unit.
By tapping "Calculate!" you will see the results if all input is correct. The results are shown graphically (as shown below). You will see the pushover curve and its bilinearization (by the way, this is a good opportunity to check your input). Below that, you will see the target displacement estimated graphically on the equivalent single degree of freedom system. If you are interested in detailed results, you can purchase the full version of the app.
As with any other Structural Engineering app, you must understand the theory behind the app before using it. Some resources that can serve as a starting point are listed below in the Bibliography section. [1, 2].
If you have comments and suggestions, feel free to contact us.
BIBLIOGRAPHY
[1] Fajfar P. A Nonlinear Analysis Method for Performance‐Based Seismic Design. Earthq Spectra 2000;16:573–92. doi:10.1193/1.1586128.
[2] CEN. EN 1998-1. Eurocode 8: Design of structures for earthquake resistance - Part 1: General rules, seismic actions and rules for buildings. 2004.