Element description

The axially equilibrated displacement-based element (DB/ae) is a distributed plasticity displacement-based element in which axial equilibrium is strictly verifiedalong the element length. The assumed transversal displacement field ensures a linear curvature profile, which is used to simulate the effect of tension shift in RC members subjected to lateral loading.

Corresponding documentation

Journal article:

Axially equilibrated displacement-based beam element for simulating the cyclic inelastic behaviour of RC members, Earthquake Engineering and Structural Dynamics, 2017.

It contains the motivation, mathematical background and validation of the proposed finite element.

Conference paper:

Axially equilibrated displacement-based beam element: implementation in Opensees and application to dynamic analysis of Structures, COMPDYN, Rhodos, 2017.

It outlines the implementation of the finite element in the OPENSEES platform.

Application examples

The tcl files required to run the application examples of Section 3 of the paper "Axially equilibrated displacement-based beam element: implementation in Opensees and application to dynamic analysis of structures" are provided in the following:

Static Analysis: run MAIN_push and MAIN_Cyclic for pushover and reversed cyclic analysis

Dynamic Analysis: run MAIN_dyn for dynamic analysis

Element source code

Header file .h

Source file .cpp

The element is an adaptation of the existing DispBeamColumn2d class element. The modifications regard the "update" and the "getBasicStiff" methods. Two new methods are added which are:

1. "getAxialStrainIncrement": perform auxiliary computations and returns the axial strain incrementsat the integration points;

2. "getSectionalAxialForceUnbalance": perform auxiliary computations and returns the unbalance in the axial forces at the integration points.

Download of the opensees.exe containing the new element

Downolad the executable here (64-bit version, built for a Windows machine)

Citation

D. Tarquini, J.P. Almeida, K Beyer (2017) "Axially equilibrated displacement-based beam element for simulating the cyclic inelastic behaviour of RC members", Earthquake Engineering and Structural Dynamics; 46:1471–1492, doi:10.1002/eqe.2865