Jindřich Čech

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.

Impact of Increased Temperature on Cohesiveness of Textile Glass Reinforcement with UHPC Matrix

The contribution is focused on research results of thin elements with UHPC matrix reinforced by textile glass reinforcement. A set of three test samples with size of 1100 x 120 x 20 mm were produced in laboratories of the Klokner Institute. Using accompanying tests the material characteristics of the concrete matrix and the textile glass reinforcement were determined. This reinforcement is modified by a protective epoxy surface layer, co called coating. The reason of the coating is to prevent a formation and a development of corrosive processes on the reinforcement texture. The samples were tested at four-point bend test in a thermal chamber. The thermal chamber is a space where it is possible to gradually regulate the temperature up to 75 °C under a constant value of a loading. In the course of the temperature increasing is using a measuring unit measured mainly bend in the middle of the span in time and the course of an inner and outer temperature. The impact of the increased temperature on the cohesiveness of the non-conventional reinforcement and the UHPC matrix is evaluated from the monitored data.

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.

Computer Nonlinear Analysis of the Formation and Development of Cracks in a Travertine Stone Pavement Exposed to Bending Stress Caused by a Single Load

This paper focuses on a computer nonlinear analysis of the formation and development of cracks in a travertine stone pavement. The causes of cracking in the upper travertine layer of the tested multi-layer floor are modeled and investigated by a computer nonlinear static analysis. The paper illustrates the setting of material characteristics of the stone in the design of the material model according to the performed destructive and non-destructive laboratory tests.

Computer Nonlinear Analysis of the Formation and Development of Cracks in a Reinforced Concrete Slab Loaded by a Planar Uniform Load

The paper focuses on a computer nonlinear analysis of the formation and development of cracks in a concrete slab exposed to a uniform continuous load on the lower surface. The analysis is based on an actual example of the formation and development of cracks in a basement slab exposed to ground water buoyancy.

Loading Tests of Experimental Models of an Integral Bridge Loaded by the Effects of Water Pressure during Floods

This paper presents an experimental and computer analysis of an integral bridge structure exposed to a load caused by the horizontal pressure of water during floods. The paper focuses on the residual load-bearing capacity of an integral bridge structure that was able to withstand the effects of flooding. Three models of integral bridges built to a scale of 1:5 were made for the purpose of testing. The frames have a span of 2.6 m, the thickness of the supports is 0.2 m, and the thickness of the deck in the middle is 0.125 m. The frames are loaded by horizontal forces representing the water pressure during floods. Each frame is securely anchored at the base and is gradually loaded by two horizontal forces situated in the corners of the frame. Loading is interrupted when cracks of 0.3 mm appear. Subsequently, the frame is loaded by a pair of vertical forces acting on the top surface of the frame, up to the load-bearing capacity. This procedure was established in order to find the residual load-bearing capacity of an integral bridge that managed to withstand the effects of flooding. . The paper includes a set of computer simulations.

Prestressed I-Beams of 12 m Span Made of Ultra-High Performance Concrete for Construction of Railway Bridges

This paper focuses on research of prestressed I-beams made of ultra-high performance concrete (UHPC), which are designed to be structural elements in small and medium span railway bridges. Prestressed concrete I-beams are designed with ten prestressing cables in the bottom flange. The prestressed beams are laid close together in the actual structure, with panels inserted between them. The entire structure will subsequently become monolithic. At the present time, I-beams made of rolled steel are commonly used as structural elements in this type of structure. The advantage of these types of structures lies in their having low construction height. This paper presents a computer and experimental analysis of loading of UHPC prestressed I-beams. For the purpose of the experiments, three specimens of 12 m span were made. The specimens were subsequently tested in the laboratory in four-point bending tests. The paper presents the process and results of the experiments. Simultaneously with the experiments, computer analyses were created in which optimization of the material and geometric parameters of the beams were carried out. The paper demonstrates the correspondence of the experimental and computer-simulated load test results.

Prestressed I-Beams Made of Ultra-High Performance Concrete for Construction of Railway Bridges

This paper focuses on research into prestressed I-beams made of ultra-high-performance concrete, which are designed to be structural elements in small and medium span railway bridges. Prestressed concrete I-beams are designed with ten prestressing cables in the bottom flange. The prestressed beams are laid close together in the actual structure with panels inserted between them. The entire structure will subsequently become monolithic. At the present time, I-beams made of rolled steel are commonly used as structural elements in this type of structure. The advantage of these types of structures lies in their having a low construction height. This paper presents a computer and experimental analysis of the loading of UHPC prestressed I-beams. For the purpose of the experiments, several specimens of 7 m span were made. The specimens were subsequently tested in the laboratory in four-point bending tests. The paper presents the process and results of the experiments. Simultaneously with the experiments, computer analyses were created in which optimization of the material and geometric parameters of the beams were carried out. The paper demonstrates the correspondence of the experimental and computer-simulated load test results.