Mladen Bulić

The Guidelines for Modelling the Preloading Bolts in the Structural Connection Using Finite Element Methods

The aim of this paper is the development of the two different numerical techniques for the preloading of bolts by the finite element method using the software Abaqus Standard. Furthermore, this paper gave detailed guidelines for modelling contact, method for solving the numerical error problems such as numerical singularity error and negative eigenvalues due to rigid body motion or the problem of the extensive elongation of bolts after pretension which is occurring during the analysis. The behaviour of bolted joints depending on the two different approaches of pretension was shown on the example of an extended end-plate bolted beam-to-column connection under the monotonic loading. The behaviour of beam-to-column connection was shown in the form and moment-rotation ( - ) curves and validated by experimental test. Advantages and disadvantages of pretension techniques, as well as the speed of numerical models, were also presented in this paper.

Nonlinear seismic analysis of steel frame with semi-rigid joints

U radu je prikazana nelinearna seizmicka analiza celicnog okvira bez dijagonala, pri cemu je uzeto u obzir stvarno ponasanje realnih djelomicno krutih prikljucaka na nacin da je za odabrani prikljucak prethodno provedena numericka simulacija. Rezultat toga je dijagram odnosa momenta savijanja i rotacije prikljucka, koji je aproksimiran kao trilinearan, i ukljucen u seizmicku analizu primjenom nelinearne staticke metode N2. Određeni su apsolutni i relativni pomaci okvira te izvrsena usporedba dobivenih rezultata s rezultatima za celicni okvir s apsolutno krutim prikljuccima.

ČELIČNI PLOŠNI ELEMENTI OPTEREĆENI U SVOJOJ RAVNINI: FAKTORI IZBOČIVANJA

The aim of this paper is to present the way how the values of buckling factor are derived, which are provided as a ready-made numerical values in the existing literature on steel structures and European standards for steel structures. In this paper the stability of steel plate elements loaded in their plane is presented in the way how this problem is solved in mechanics. The general theory of stability of plates is given and the equation of buckling of plate elements is derived. The elastic critical buckling stress for plate cr  is explained as well as the plate buckling factor  k for arbitrary boundary conditions, arbitrary distribution of external loading on the plate and arbitrary relationship between length and width of the plate. In addition the values of buckling factor for various boundary conditions and arbitrary relationship between length and width of the plate are presented using the diagrams in the literature. Finally, an example of a plate element calculated analytically and computed using specialized software package EBPlate [11], which is based on the European standard EN 1993-1-5 [3], is presented.