A family of new beam finite elements for geometrically and materially non-linear static analysis of reinforced concrete planar frames is derived, in which strain measures are the interpolated unknowns. The strain localization caused by the strain softening at cross-sections is resolved by the introduction of a ‘short constant-strain element’. Comparisons between numerical and experimental results on planar frames in pre- and post-critical states show both good accuracy and computational efficiency of the formulation.

COBISS.SI-ID: 2476385

This paper presents the linearized version of the geometrically exact three-dimensional beam theory of naturally curved and twisted beams. A new finite-element formulation for the linearized theory is proposed in which only the strain vectors need be interpolated. The linear form of the consistency condition is enforced to be satisfied at chosen points. An initially curved and twisted axis of the beam is assumed which requires a special consideration of the non-linearity of spatial rotations. The accuracy and the efficiency of the derived numerical algorithm is shown via numerical examples.

COBISS.SI-ID: 3169889

A new finite-element, finite-displacement slip formulation is presented for the non-linear analysis of two-layer composite planar frames with an interlayer slip. Non-linear, time-dependent material models for the layers, and a non-linear relationship between the slip and the shear traction at the interface are assumed. The finite element is prefectly suited for practical calculations.

COBISS.SI-ID: 2475873

In practical problems the parameters of distribution can only be estimated from random samples. Hence the characteristic value is by itself a random variable. The estimates of characteristic values are strongly dependent on the distribution of a random variable. We derive the analytical solution for the characteristic value determination from random samples of normal and lognormal random variables. The results are confirmed by computer simulations. The approach is applied to the data set from bending strengths of finger jointed wooden beams.

COBISS.SI-ID: 3588449

The paper discusses the use of the ultrasonic wave transmission method in estimating the initial setting time of cement paste. Different parameters of cement paste were analysed, including water/cement ratio, type of cement, curing temperature, cement fineness, and some clinker compositions. The initial setting time of an arbitrary cement paste was found to be very accurately estimated as the time of the first inflection point on the ultrasonic pulse velocity curve, or as the time when the ultrasonic pulse velocity is close to the ultrasonic pulse velocity in water.

COBISS.SI-ID: 4294497