Petr Tej

Design of an Experimental Prestressed Vierendeel Pedestrian Bridge Made of UHPC

This paper presents the design of an experimental prestressed Vierendeel pedestrian bridge made of ultra-high performance concrete (UHPC). The structure is designed as a permanent single-span bridge with an intermediate deck. The span of the bridge structure is 61.38 m, the total width is 6.68 m, and the clearance width of the bridge is 5.30 m. The main structure of the bridge consists of two prestressed Vierendeel beams made of UHPC with dispersed steel fibres . The main beams are composed of prefabricated parts, subsequently prestressed.

Design of an Experimental Prestressed Arch Pedestrian Bridge Made of UHPC

This paper presents the design of an experimental prestressed arch pedestrian bridge made of ultra-high performance concrete (UHPC). The structure is designed as a permanent single-span bridge with an intermediate deck. The span of the bridge structure is 58.5 m, the total width is 5.1 m, and the clearance width of the bridge is 4.5 m. The main structure of the bridge consists of two prestressed beams made of UHPC with dispersed steel fibers. The main beams are composed of prefabricated parts, subsequently prestressed.

Long-Term Monitoring of a Composite Steel-Concrete Bridge on the Prague Ring Road

The composite steel-concrete bridge across the “Slavičí údolí” on the Prague ring exposed to extreme traffic is selected for present traffic flow monitoring. The response of the bridge to the traffic loads is monitored using strain gauges. The record of voltage is converted to the amount of relative deformation, respectively stress in the bottom flange of steel I beam of the bridge. In parallel with the measurements, the computer slab - wall model based on finite element method is developed. The computer model is used for comparison of calculated and measured stresses and deflections in the flanges and to determine the natural frequencies of the examined bridge structure. Calibrated measurements are used for three-year monitoring of the effects of road traffic on bridge facilitating national decision in the National Annex to EN 1991-2.

Degradation of Laminated Glass as Result of Increased Temperature

The degradation of laminated glass as a result of increased temperature has become one of the important problem of reconstructions and designs of new glass structures, for instance high-rise buildings that are exposed to the impacts of an intensive heating caused e. g. by sunshine. The temperatures during heating can reach very high values, commonly from 60 to 70 °C. The effect of heating was simulated using the thermal chamber where the glass panes with the size of 120 x 1100 mm were heated. The deformation course under the increase of temperature was continually monitored by a measuring unit. In total six types of foils joining particular layers of glass were examined. In this paper the experimentally gained results are compared with a numeric computer analysis and the particular kinds of interlayers are evaluated using the loss of shear interaction.

Prefabrication of the Thin-Walled U-Profile UHPFRC Footbridge

This article presents a mix design, preparation and production of thin-walled footbridge made from UHPFRC. Optimization of UHPFRC matrix and parameters of this material leads to the design of very thin structures. In this case an experimental pedestrian bridge was designed and prepared. Single-span bridge with span of 10 m and the clear width of 1.50 m with the total thickness of shell structure 30 - 45 mm was cast as a prefabricated element in one piece. Self-compacting character of UHPFRC with high flowability allows the production of the final structure. Extensive research was done before production of footbridge. Two versions of large scale mock-ups were casted and tested. According to the complexity of whole experiment a casting technology and production of formwork were tested and optimized many times. Experimental reached data were compared with extensive numerical analysis and the final design of structure and UHPFRC matrix were optimized in many details.

Assessment of structural condition of steel bridge in Brandýs nad Orlicí

This paper deals with structural condition assessment of historical steel through arch bridge in Brandýs nad Orlici. Structure was dynamically tested to obtain mode shapes and eigenfrequencies on non-loaded structure and to estimate logarithmic damping decrement after traffic loading. Material properties were verified. Calculation model was created to validate its statical and dynamical behaviour. Article focuses on comparison of calculated results and properties of real structure upon excitation.

Experimental and Theoretical Analysis of I-Pillars of Noise Barriers Made of Prestressed Steel Fiber Concrete, Prestressed Concrete and Reinforced Concrete with Footings Length of 600 mm

This paper deals with the experimental testing and theoretical analysis of the flexural load-bearing capacity of I-shaped pillars in noise barriers made of reinforced concrete, prestressed concrete and prestressed steel fiber reinforced concrete. The pillars were loaded as a cantilever under a flexural load, which corresponds to their actual loading when the effect of wind on the panels of the noise barrier is taken into account. For the purpose of the present research, three specimens of I-pillars were tested. The results of the experimental loading tests, as well as the calculated results and the comparison between them, are herein presented.

Tensile Test and Analysis of the Geometry of Kevlar/Epoxy Composites

This paper is concerned with the analysis of geometric composites, whose reinforcement was made of plain weave fabric with different geometries. They were determined following the basic parameters of the textiles e.g. crimp length, crimp amplitude, thickness of the woven fabric, dimensions of the cross-sectional tow (tow width, tow height) and crimp angle. The number of fibers in the warp and tow strands and number of layers in the composites were also determined. These composites comprised of the same materials were subjected to a standard tensile test, according to DIN EN ISO 14 129. The mechanical properties of the composite as a whole were determined by tensile test.

Assessment of Reliability and Overall Life-Time of the Turbo Generator in the Kamýk Power Station

This paper presents the results of measurement of the stress and the theoretical analysis of the steel structure of the Kaplan turbo generator in the Kamýk power station in the Czech Republic. Based on the number of load cycles and the finding of the maximum stress range of critical details of the most loaded part, the lower star, the residual lifetime of the turbo generator was determined.

Numerical Analysis of Damage of Precast Reinforced Concrete Structural System Caused by the Effects of Temperature Changes

This paper deals with the numerical analysis of damage to a precast reinforced concrete structural system caused by the effects of temperature changes. Specifically, the analysis aims to examine the failures in the contact place between the TT panel of the roof structure and the girder. A computer model was created based on the actual construction of the occurring disorders. Temperature changes, which act on the structure, were identified by measurements taken over a long period. The structure was modeled using GiD 11 software and calculated using the ATENA WIN program. The results of the numerical analysis and the manifestations of damage to the actual construction were mutually compared.