Experimental Verification of Pre-Stressed Beams

2014 ◽  
Vol 1054 ◽  
pp. 116-121
Author(s):  
Jan Tichý ◽  
Renata Cvancigerová
Keyword(s):  
Czech Republic ◽  
High Performance ◽  
Applied Research ◽  
High Performance Concrete ◽  
Specific Production ◽  
Ultra High Performance Concrete ◽  
The Czech Republic ◽  
Manufacturing Facility

The paper is a follow-up to previous presentations regarding the experience with ultra-high-performance (UHPC) concrete in the Czech Republic. It will present specific production and testing of pre-stressed beams in the company Skanska a.s. In 2013, the manufacturing facility of the company Skanska a.s. in Štětí, the Prefa plant, produced several series of pre-stressed beams made of ultra-high-performance concrete. The last series of pre-stressed beams was kept in a storage facility in Štětí over winter. In February 2014, destructive tests were carried out on two of the beams in the Štětí facility directly. Another two beams are used for monitoring the long-term changes under continuous load. A description of the tests and their results will be published in the paper. At the same time, a number of accompanying tests were carried out in the Klokner Institute of ČVUT in Prague. The results of these tests will also be mentioned in this paper. The experience and results have been achieved thanks to the grant project no. TA01010269 “Applied research of ultra-high-performance concrete (UHPC) for precast units of structures” subsidized by the Technology Agency of the Czech Republic.

Construction of the First Footbridge Made of UHPC in the Czech Republic

2015 ◽  
Vol 1106 ◽  
pp. 8-13 ◽  
Author(s):  
Petr Koukolík ◽  
Jan L. Vítek ◽  
Robert Brož ◽  
Robert Coufal ◽  
Milan Kalný ◽  
...  
Keyword(s):  
Czech Republic ◽  
Experimental Verification ◽  
High Performance ◽  
High Performance Concrete ◽  
Structural Elements ◽  
Ultra High Performance Concrete ◽  
The Czech Republic ◽  
Material Parameters ◽  
Load Carrying ◽  
Utility Vehicle

Footbridge over the Labe River in Celakovice is a cable stayed structure with the main span 156 m long. It is designed for pedestrians, cyclists and also a light utility vehicle may pass over the footbridge. Until now, the footbridge has a record span of the cable stayed structure in the Czech Republic. The ultra high performance concrete (UHPC) was first applied for the load carrying structure on the footbridge at the Czech Republic. The pylons are made of steel and the stays are made of locked coil strands. Since no obligatory codes were available for the design of structures made of UHPC, the extensive experimental verification of material parameters and structural elements was necessary.

Volumetric Changes of the UHPC Matrix and its Determination

2016 ◽  
Vol 827 ◽  
pp. 215-218 ◽  
Author(s):  
David Čítek ◽  
Milan Rydval ◽  
Jiří Kolísko
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
Experimental Tests ◽  
Structure Design ◽  
Ultra High Performance Concrete ◽  
Fine Grained ◽  
Durability Properties ◽  
Shrinkage And Creep

Research in the Ultra-High Performance Concrete applications field is very important. Current experiences shows that the structure design should be optimize due to relatively new fine-grained cement-based Hi-Tech material with excellent mechanical and durability properties. It is not sure if some of the volumetric changes like creep or shrinkage has or has not an impact on an advantage for the construction and for the structure design. The effect of the shrinkage and creep of common used concretes are well known and well described at publications but the effect of volumetric changes of the UHPC is mostly unknown because of the fact that some of experimental tests are long term and the development of UHPC is still in its basics. A lot of works are focused on a basic mechanical properties and durability tests.

scholarly journals Study of legislative and administrative obstacles to SMEs business in the Czech Republic and Slovakia

2020 ◽  
Vol 11 (4) ◽  
pp. 689-719
Author(s):  
Beata Gavurova ◽  
Jaroslav Belas ◽  
Yuriy Bilan ◽  
Jakub Horak
Keyword(s):  
Czech Republic ◽  
Value Added ◽  
Business Environment ◽  
The Czech Republic ◽  
Advanced Economies ◽  
Stable Conditions ◽  
The Eu ◽  
Administrative Obstacles

Research background: SMEs represent an integral part of the economy environment in a majority of the countries all over the world. They signify the most efficient, progressive, and important part of the advanced economies. The long-term effort of the EU countries, as well as other advanced economies is to create quality and stable conditions for their development in order to be able to respond to all the possible changes in the business environment that is being changed to more and more comprehensive in the recent time. Purpose of the article: The objective of the contribution is to examine administrative and legislative obstacles to SMEs business in the Czech Republic and Slovakia and the quantification of the differences in perceiving legislative and administrative obstacles to business by entrepreneurs in both countries. Methods: A questionnaire survey was conducted within SMEs in the Czech Republic and Slovakia in 2019. The research sample included 641 SMEs, 312 from the Czech Republic and 329 from Slovakia. We focused on 5 dimensions related to legislative and administrative obstacles to SMEs business within which selected statements were examined. Contingency tables were used to analyze the ratios of the examined variables. Findings & Value added: The differences detected in both countries in the respondents´ perception and assessment are evidence of the changes in the business environment of both countries, giving rise to the questions about the extent to which the legislative and administrative obstacles, as well as the obstacles related to law enforcement and bureaucracy are acceptable and by which groups of entrepreneurs. The results of the research provide valuable findings for the creators of regional and national policies, and represent a valuable basis for the creation of the concepts focused on the SMEs´ development in both countries.  The results of the study also support the implementation of follow-up research in this area that will reveal other determinants affecting the development of SMEs. They also create a valuable platform for the construction of national and international benchmarking indicators in this area and the implementation of comparative analyses. This will also support the methodological area necessary for a creation of high-quality concepts and strategies.

Cable-Stayed Footbridge with UHPC Segmental Deck

2014 ◽  
Vol 629-630 ◽  
pp. 64-70 ◽  
Author(s):  
Milan Kalný ◽  
Vaclav Kvasnička ◽  
Jan Komanec ◽  
Jan L. Vítek ◽  
Robert Broz ◽  
...  
Keyword(s):  
Life Cycle Cost ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Light Weight ◽  
Ultra High Performance Concrete ◽  
Ongoing Research ◽  
The Czech Republic ◽  
The Public ◽  
Design And Implementation

Ongoing research and development of ultra-high performance concrete (UHPC) in the Czech Republic has been utilized in design and implementation of light-weight segmental deck of the cable-stayed footbridge over the Labe River in Celakovice with main span of 156 m. Detailing, design issues, construction method and efficiency of using UHPC on this large span lightweight bridge is described in the paper. The superstructure of the Celakovice footbridge was completed in the December 2013 and the bridge was opened for the public in April 2014. Main advantages of this project is not only low maintenance and reasonable life cycle cost but also favourable tender price which was achieved by the contractor Metrostav a.s. due to combination of high-strength modern materials steel and UHPC.

Development on the Corrosion of Steel Fiber and Prevention in the Ultra-High Performance Concrete (UHPC)

2021 ◽  
Vol 1036 ◽  
pp. 358-370
Author(s):  
Zhen Wen Guo ◽  
Xin Zhi Duan ◽  
Qiang Wang ◽  
Si Jia Wang ◽  
Xiao Lu Guo
Keyword(s):  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Chloride Ions ◽  
Control Methods ◽  
Ultra High Performance Concrete ◽  
Hybrid Fibers ◽  
Steel Bar ◽  
Corrosion Of Steel

Chloride ions, water, and oxygen could cause the corrosion of steel fiber in the aggressive environment. The corrosion of steel fiber in UHPC is a long-term process and the rate is very slow. As one of the important components of ultra-high performance concrete (UHPC), the corrosion of steel fiber is the result of multiple factors. The characteristics of steel fiber corrosion in UHPC, the factors influencing the corrosion of steel fiber in UHPC (including nanomaterials, curing condition and crack width), and effects of steel fiber corrosion on the UHPC performance (including mechanical properties, matrix rehydration and corrosion of steel bar), are emphatically elaborated. And the control methods of steel fiber corrosion in UHPC are briefly introduced, i.e. hybrid fibers and stainless steel fibers.

scholarly journals Utilizing Iron Ore Tailing as Cementitious Material for Eco-Friendly Design of Ultra-High Performance Concrete (UHPC)

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1829
Author(s):  
Gang Ling ◽  
Zhonghe Shui ◽  
Xu Gao ◽  
Tao Sun ◽  
Rui Yu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Carbon Emission ◽  
Iron Ore ◽  
High Performance Concrete ◽  
Cementitious Material ◽  
Early Age ◽  
Ultra High Performance Concrete ◽  
Iron Ore Tailing

In this research, iron ore tailing (IOT) is utilized as the cementitious material to develop an eco-friendly ultra-high performance concrete (UHPC). The UHPC mix is obtained according to the modified Andreasen and Andersen (MAA) packing model, and the applied dosage of IOT is 10%, 20%, and 30% (by weight), respectively. The calculated packing density of different mixtures is consistent with each other. Afterwards, the fresh and hardened performance of UHPC mixtures with IOT are evaluated. The results demonstrate that the workability of designed UHPC mixtures is increased with the incorporation of IOT. The heat flow at an early age of designed UHPC with IOT is attenuated, the compressive strength and auto shrinkage at an early age are consequently reduced. The addition of IOT promotes the development of long-term compressive strength and optimization of the pore structure, thus the durability of designed UHPC is still guaranteed. In addition, the ecological estimate results show that the utilization of IOT for the UHPC design can reduce the carbon emission significantly.

Design of an Experimental Arch Pedestrian Bridge Made of UHPC

2016 ◽  
Author(s):  
Petr Tej ◽  
Petr Kněž ◽  
Jan Mourek
Keyword(s):  
Shell Structure ◽  
High Performance ◽  
High Performance Concrete ◽  
Total Width ◽  
Bridge Structure ◽  
Ultra High Performance Concrete ◽  
Pedestrian Bridge ◽  
Computer Analyses ◽  
Term Monitoring

This paper presents the design of an experimental arch pedestrian bridge made of ultra-high performance concrete (UHPC). The structure is designed as a permanent single-span bridge. The span of the bridge structure is 10.00 m, the total width of shell structure is 0.03 m, and the clearance width of the bridge is 1.50 m. The main structure of the bridge is one prefabricated arch shell structure made of UHPC with dispersed steel fibers without conventional reinforcement. Simultaneously with the designing of the bridge, computer analyses were created in which optimization of the material and geometric parameters of the structure were carried out. The presentation on the conference will contain also production and assembly of the pedestrian bridge. The presentation will include also long-term monitoring of the specimen of the shell structure in 1:1 scale and finally experimentally obtained load bearing capacity of the specimen. Production and testing of the bridge is scheduled for July 2016.

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