Zdeněk Sokol

Component Method for Historical Timber Joints

Timber structures represent one of the most important ancient engineering works spanning over considerable distances. They involve not only an evidence of structural knowledge and creativity of their makers but also a good deal of structural beauty, Figure 1.

Temperature of connections during fire on steel framed building

To study the global structural and thermal behaviour of buildings in fire, a research project was conducted including a fullscale test on a three storey steel frame building at Mittal Steel Ostrava before demolition. The main goal of the experiment was to verify the method for predicting joint temperatures and to improve it for the cooling phase. The fire compartment extending over a floor area of 24 m2 was built on the second floor. The fire load was 140 kg/m2 of wood and the ventilation was limited to an opening of 1,400 × 1,970 mm. This paper presents the time-temperature curves showing the development of the fire in the compartment and in the primary and secondary beams and its header plate connections. Comparisons are made between the test results and the temperatures predicted by the structural Eurocodes. The sensitivity of the connection behaviour to the estimated temperatures and associated degradation in material properties during the fire is demonstrated.

Stiffness of cover plate connections with slotted holes

Abstract This paper describes the prediction of stiffness of bolted cover plate connections with slots perpendicular to the acting force. The work is based on three sets of tests: experiments on connections with more bolt rows and different bolt forming technology performed at the CRIF laboratory in Liege, experiments with long slots completed at the Laboratory of Technical University Nottingham, and experiments with components carried out at the Czech Technical University in Prague. The work shows the application of the component method to the prediction of stiffness of the cover plate connections. The component bolt/plate in bearing is evaluated. Special attention is paid to the modelling of the bolt force distribution for different bolt tolerances.

Numerical Design Model of Joints

This article compares two approaches to design of endplate joints of steel structures: the component method and finite element method. Component method is nowadays the most commonly used method for the design of joints. This analytical method is simple and reliable for the design of commonly used joints. However, this method is hardly applicable to the design of complex joints. For this reason, it is expected to create a numerical model using finite element method for the design of such complex joints.

Connections of Trapezoidal Sheets under Fire

This paper describes two different experiments on connections of trapezoidal sheets under elevated temperatures. The first experiments were tensile tests carried out on four sets of tests with screwed connections under ambient and elevated temperatures. One diameter of self-drilling screws and three different thicknesses of trapezoidal sheets were used. The applied screws were without washers, or with sealed or steel washers. The second experiment was performed in a laboratory furnace to check the catenary action of a thin-walled trapezoidal sheet. The basic theory tested in this experiment was that in the first phase of the fire the sheet behaves as a simply supported beam, while in the second phase the load bearing is transferred by a tension membrane. These experiments will be used to develop a design model of connections at high temperatures. High fire resistance of the trapezoidal sheet, dependent on suitable design of the screwed connection to the bearing structure, was confirmed. The experiment with the simple beam also confirmed catenary action.

Modelling of Joints of Sandwiches Panels

The lightweight sandwiches panels are produced by a modern and environmental controlled technology. A typical sandwich panel consist of two covering steel sheets, generally made of the trapezoidal or light profiled steel sheets, and of a weak lightweight core. The increasing use of lightweight sandwiches panels in industrial and civil buildings requires the development of suitable methods for analysis. The response of single panel as well as behaviour of whole structure is influenced by joints between sandwiches panels and framework. The stiffening effect of the cladding panels on the structural behaviour of the structure, the stress skin procedure, with the respect to the connections was evaluated in [3] to observe the behaviour under the seismic loading. The published analysis [1] neglects stress distribution between the both metal faces. Only inner sheet is assumed to carry the applied loads and the bearing capacity of the connection, see [2].