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Kmitání mostů pod vysokorychlostními vlaky
Frýba, Ladislav
Teoretický model vysvětluje dynamické chování železničních mostů zatížených vysokorychlostními vlaky. Metoda integrálních transformací parciální diferenciální rovnice dá průhyby, napětí a svislá zrychlení nosníku v uzavřeném tvaru. Numerická studie poskytuje přehled o vlivu jednotlivých parametrů.
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DELIVERABLE D9.6 Small sample testing
Cikrle, P. ; Drdácký, Miloš ; Lesák, Jaroslav ; Slížková, Zuzana ; Válek, Jan ; Vavřík, Daniel ; Zíma, Pavel
A number of in-situ tests for mechanical material properties is readily available but there were developed improved methodologies which met the requirements and specifics of this project. It the case of historic masonry there was necessary to deal with a common additional problem, which is the testing of non-standards samples. This was for example a problem of testing of historic bedding mortars or renders, where a typical width of sample is around 10 mm. It comes along with the general need for small ů micro samples with regards to the protection of historic masonry where a minimum intervention is always required. Mechanical properties in bending were tested on non-standard mortar samples which were supplemented symmetrically on both ends with two 'prostheses'. According to the results of the tests comparing the flexural strength of pure mortar beams with the strength ascertained on prosthesized identical material the influence of prosthesization is negligible. Testing of stone samples involved comparison of the compressive and split tensile strength of specimens of standard dimensions and specimens of smaller dimensions
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DELIVERABLE D9.5 Damaged Masonry
Drdácký, Miloš ; Lesák, Jaroslav ; Urushadze, Shota ; Válek, Jan
Several masonry trial wallets were prepared for the testing. The specimens were mounted into a special testing rig which enabled simultaneous uniform compression and cyclic horizontal loading on the top of the tested specimen. There were four hydraulic jacks generating the vertical load which was transmitted to the wall by eight ties and a steel 'hatö on the top of the wall. Horizontal displacement (force) on the top of the wall was introduced from servo-hydraulic MTS actuator of 250 kN capacity. Experimental part involved testing of brick walls for determination of crack pattern development under various combined loadings and testing of brick, sandstone and marly lime stone walls for crack and damage determination by application of NDT methods. Four approaches have been studied and evaluated: i) sonic wave propagation, ii) stress wave propagation, iii) crack pattern development, iv) modal analysis in which also a case study has been accompanied with a related pilot shaking table test of a one leaf masonry model.
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Koncept sensitivity - Nástroj pro konstituční modelování materiálu výsypek hnědouhelných dolů
Mašín, David
An original approach to constitutive modelling of double-porosity materials is presented in the paper. The approach is based on the parallel in the mechanical behaviour of these materials and sensitive clays. After summary of the framework for the behaviour of natural clays (Cotecchia a Chandler, 2000) a new simple constitutive model based on the Modified Cam-Clay model, which allows for modelling of the degradation of the intergranular porosity, is proposed. Finally, its application to the double-porosity materials is discussed.
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