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The purpose of this study is to numerically model the rigid pavement resting on two-parameter soil and to examine its modal parameters.

This study is carried out using a one-dimensional beam element with three rotational and three translational degrees of freedom based on the finite element method. MATLAB programming is used to perform the free vibration analysis of the rigid pavement.

Cyclic frequency and their corresponding mode shapes were determined. It has been investigated how cyclic frequency changes as a result of variations in the thickness, span length of pavement, shear modulus, modulus of subgrade, different boundary conditions and element discretization. Thickness of the pavement and span length has greater effect on the cyclic frequency. Maximum increase of 29.7% is found on increasing the thickness, whereas the cyclic frequency decreases by 63.49% on increasing span length of pavement.

The pavement's free vibration is the sole subject of the current investigation. This study limits for the preliminary design phase of rigid pavements, where a complete three-dimensional finite element analysis is unnecessary. The current approach can be extended to future research using a different method, such as finite element grilling technique, mesh-free technique on reinforced concrete pavements or jointed concrete pavements.

The finite element approach adopted in this paper involves six degrees of freedom for each node. Furthermore, to the best of the authors’ knowledge, no prior study has done seven separate parametric investigations on the modal analysis of rigid pavement resting on two-parameter soil.

The paper aims to deal with the enhancement of a simplified method for the design of concrete columns subject to fire toward applications on circular and tubular cross-sections. The original zone method, developed by Hertz as a plastic design method, has been extended by Achenbach for the use as a nonlinear method. This proposed extended zone method (EZM) is verified by checking the theoretical background and is successfully validated by the recalculation of laboratory tests.

The zone method assumes a reduction of a cross-section by a “damaged” zone. The remaining area is modeled with the constant, temperature-dependent material properties. The equations for the calculation of the damaged zone to model the loss of cross-section resistance or stiffness are derived. The proposed equations are validated by the recalculation of laboratory test and compared to the results of the advanced method (AM).

It can be shown that the EZM is suitable for the check of the fire resistance of circular concrete columns and leads to a safe and economic design. The method provides a suitable alternative to more sophisticated AM. The further extension toward tubular spun columns is discussed und is the object of the ongoing research.

Presented enhancement extends the range of applications of the EZMs toward circular and tubular cross sections, which has previously not been examined.