This paper presents some numerical studies carried out in order to investigate the performance of a bolted extended end-plate beam-to-column connection subjected to combined bending moment and axial force. This investigation utilizes nonlinear finite element modeling techniques using ABAQUS, considering both geometric and material nonlinearities. The aim of the study is to analyze the influence of various levels of axial force, tension or compression, on connection characteristics: moment-rotation curve, connection strength, connection stiffness, distribution of stresses in the connection components, connection failure mode. This study is based on a sensitivity analysis of this type of connection, subjected to bending and axial force, to the variation of some geometric or structural parameters of joint. The performed investigations have shown that axial forces influences the moment resistance of the connection, but its initial stiffness does not change significantly under an additional axial force in the beam.

End-plate connections with preloaded high strength bolts represent a convenient, fast and accurate solution for beam-to-column joints. The behavior of framework joints build up with this type of connection are sensitive dependent on geometrical and material characteristics of the elements connected. This paper presents results of parametric analyses on the behavior of a bolted extended end-plate connection using finite element modeling program Abaqus. This connection was experimentally tested in the Laboratory of Faculty of Civil Engineering from Cluj-Napoca and the results are briefly reviewed in this paper. The numerical model of the studied connection was described in detail in [1] and provides data for this parametric study.

This paper presents an experimental investigation of a statically monotonic loaded extended end-plate connection, with preloaded high strength bolts, that was carried out at Laboratory of Faculty of Civil Engineering from Cluj-Napoca. A finite element model using the software package Abaqus [1] was developed in parallel. In order to calibrate the numerical model, the results were analyzed on the basis of moment-rotation curves, stress distribution state and the failure mode of connection. Then, a study was conducted on the numerical model by using a high strength steel (HSS) and changing the stiffness and strength characteristics of some elements. Validation of the numerical modeling was performed against the experimental results and it can be seen that good agreements exist in general.

Beam-to-column end-plate bolted connections are usually used as moment-resistant connections in steel framed structures. For this joint type, the deformability is governed by the deformation capacity of the column flange and end-plate under tension and elongation of the bolts. All these elements around the beam tension flange form the tension region of the joint, which can be modeled by means of equivalent T-stubs. In this paper a beam-to-column end-plate bolted connection is substituted with a T-stub of appropriate effective length and it is analyzed using the commercially available finite element software ABAQUS. The performance of the model is validated by comparing the behavior of the T-stub from the numerical simulation with the behavior of the connection as a whole. The moment-rotation curve of the T-stub obtained from the numerical simulation is compared with the behavior of the whole extended end-plate connection, obtained by numerical simulation, experimental tests and analytical approach.

The improvement of the electronic systems of computation made the use of the finite element method (FEM) possible in the current research and design activity. In the field of the design steel frames, the finite element analysis (FEA) of the joints offers the possibility to simulate their real behavior at low costs and in a relatively short period of time compared with the experimental tests. This paper presents the analysis with finite elements of a steel joint with end plate and prestressed bolts, using the ABAQUS finite element software code. The results obtained after the numerical simulation were compared with the experimental data in order to validate the model.

In Technical University of Cluj Laboratory, several tests according to ECCS loading procedure were carried out. The tested specimens were composite columns of fully encased type subject to a variable transverse load at one end while keeping a constant value of the axial compression force into them. The complex evolution of the hysteretic cyclic curves representing the transverse force versus the associated displacement up to a pronounced deterioration of the column bases leads to a simplified analytical characterization for the loss of resistance and the reduction of stiffness. The analytical work was made at INSA Rennes, under the coordination of prof. Jean-Marie Aribert. A possible approach to investigate better the column seismic performances is illustrated in the last part going from a basic experimental research to a theoretical interpretation in terms of q factor of inverted pendulum structures (one-storey frame) for which the dissipative zones are located in the composite columns.

The modeling by the finite element method of a beam to column steel connection with end plate and prestressed bolts was made in order to perform investigations on the M versus theta joint characteristic. Ls-Dyna explicit nonlinear solver was used to perform the analysis. An efficient solution for the prestressed bolts simulation was obtained. The influence of the static and dynamic frictional coefficients, acting on the contact interfaces between the joint components, can be studied as well, by using the derived finite element model.