The present paper of a series deals with the experimental characterisation of tensile splitting strength and compressive behaviour of different structural concrete containing different volume of steel fibre reinforcement (0 V%, 0.5 V%, 1.0 V%, 75 kg/m3, 150 kg/m3) and different configuration of steel fibres (crimped, hooked-end). Tensile splitting tests were carried out on standard cylinder (∅ = 150 mm, l = 300 mm) specimens (so-called Brazilian test) considering random fibre orientation. Since the fibre orientation may significantly affect the tensile behaviour test series were also performed on cross-section (100 mm × 100 mm) of steel fibre reinforced concrete beams (100 mm × 100 mm × 240 mm) sawn out of steel fibre reinforced slab elements. Taken as a whole behaviour of steel fibre reinforced concrete was examined in tension taking into consideration different experimental parameters such as fibre content, type of fibres, fibre configuration, fibre orientation, size of specimens (size effect) and concrete mixture.
The present paper of a series deals with the experimental characterisation of compressive strength and compressive behaviour (stress-strain relationship) of different structural concrete containing different volume of steel fibre reinforcement (0 V%, 0.5V%, 1.0V%, 75 kg/m3, 150 kg/m3) and different configuration of steel fibres (crimped, hooked-end). Compressive tests were carried out on standard cube (150 mm × 150 mm × 150 mm) and cylinder (Ø = 150 mm, l = 300 mm) specimens considering random fibre orientation. Since the fibre orientation may significantly affect the compressive behaviour, test series were also performed on cylinders (Ø = 70 mm, l = 100 mm) drilled out of fibre reinforced concrete beams and prisms (100 mm × 100 mm × 240 mm) sawn out of steel fibre reinforced deep beams. Throughout the tests stress-strain relationships were registered on the standard cube and cylinder specimens as well. In conclusion, behaviour of steel fibre reinforced concrete was examined in compression taking into consideration different experimental parameters such as fibre content, type of fibres, fibre configuration, fibre orientation, size of specimens (size effect) and concrete mixture.
The present paper of a series deals with the experimental characterisation of flexural toughness properties of structural concrete containing different volume of hooked-end steel fibre reinforcement (75 kg/m3, 150 kg/m3). Third-point flexural tests were carried out on steel fibre reinforced concrete beams having a cross-section of 80 mm × 85 mm with the span of 765 mm, hence the shear span to depth ratio was 3. Beams were sawn out of steel fibre reinforced slab elements (see Part I) in order to take into consideration the introduced privilege fibre orientation (I and II) and the position of the beam (Ba-a, Ba-b, Ba-c) before sawing (see Part I). Flexural toughness properties were determined considering different standard specifications, namely the method of the ASTM (American Standards for Testing Materials), the process of the JSCE (Japan Society of Civil Engineering), and the final proposal of Banthia and Trottier for the post cracking strength. Consequently, behaviour of steel fibre reinforced concrete was examined in bending taking into consideration different experimental parameters such as fibre content, concrete mix proportions, fibre orientation, positions of test specimens in the formwork, while experimental constants were the size of specimens, the type of fibre used and the test set-up and test arrangement.
Authors:Smith Sundar, Mohini Sain, and Kristiina Oksman
cellulose long fibers (CLF)-based PLA composites prior to fiberorientation. Thermal analysis techniques such as thermo gravimetric analysis (TG), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) were used to characterize the
The papers of the series deal with experimental characterisation of mechanical as well as structural properties of different steel fibre reinforced concretes that can be used for several structural applications. An extensive experimental programme (six years) has been developed to investigate the effect of steel fibre reinforcement on the mechanical performance and structural behaviour of concrete specimens. Specimens and test methods were selected to be able to detect realistic behaviour of the material, representing clear effect on the structural performance. Material compositions, test methods, type of test specimens will be detailed in the presented paper (Part I).
Furthermore, compressive strength (Part II), stress-strain relationship (Part II), splitting strength (Part III) and toughness (Part IV) will also be discussed. In the light of the motivation to determine the structural performances of 1D concrete structural element affected by steel fibre reinforcement, bending and shear behaviour (Part V) as well as serviceability state (Part VI) of steel fibre reinforced concrete beams will be analysed. Since normal force — prestressing force — can affectively be used to improve the structural performances of RC element flexural tests were carried out on prestressed pretensioned steel fibre reinforced concrete beams (Part VII). Moreover, focusing on the in-plane state of stresses for 2D structures, behaviour of steel fibre reinforced concrete deep beams in shear and steel fibre reinforced concrete slabs (Part VIII) in bending will be explained. Finally, based on the wide range of the experimental and analytical studies on the presented field, a new material model for the 1D uniaxial behaviour (Part IX) and its possible extension to the 3D case (Part X) will be described hereafter. All papers will put emphasis on the short literature review of the last four decades.
A sensitive method to characterize the thermomechanical behaviour of fiber reinforced composites is the dynamic mechanical
thermoanalysis (DMTA) method. A Round-Robin-test with five different institutes was conducted to determine the role of the
fiber orientation, processing conditions, test apparatus, the mode of loading, and the matrix materials on the determination
of the glass transition temperature (Tg). The result shows that the DMTA is a suitable method to analyze Tg of long fiber composites. However, some major problems have to be taken into consideration:
- A direct comparison of results from different DMTA-systems is not possible
- The real temperatures in the specimens deviate from the temperatures displayed by the DMTA measuring system
- There is no clear and common evaluation method for the glass transition temperature.
Authors:Alaa Al-Fatlawi, Károly Jármai, and György Kovács
symmetrical concerning to the mid-plane of the sandwich structure. Every skin face-sheet composed of 4-layers. The fiberorientation in the face-sheets is having cross ply (0°, 90°) and angle ply ±45°. Table III includes the mechanical properties of the
Mind az acél, mind a szintetikus szálerősítésű betonok elterjedése és használata az iparban folyamatosan igényli a számítási módszerek fejlesztését. Az egységnyi keresztmetszeten áthaladó szálak darabszáma egy fontos paraméter: egyrészt jól jellemzi a szálak hatékonyságát, másrészt a próbatest eltört keresztmetszetén levő szálak megszámolásával a szálak elkeveredésének egyenletességét vizsgálhatjuk vagy az eredmények szórását csökkenthetjük. A legtöbb anyagmodell kiinduló paramétere ezért az egységnyi keresztmetszeten áthaladó szálak darabszáma.
A szálerősítésű betonban elhelyezkedő szálaknál feltételezzük az egyenletes, homogén elkeveredést és a véletlenszerű orientációt. Ez az orientáció azonban a zsaluzat közelében megváltozik, a szálak részben irányítottá válnak, ami hatással van az egységnyi keresztmetszeten áthaladó szálak darabszámára is. Ezen darabszámok megállapítása már a szálerősítésű beton kezdeti vizsgálatakor is foglalkoztatta a kutatókat, ennek megállapítására elméleti, szemi-empirikus és empirikus képletek egyaránt léteznek az irodalomban. Jelen cikkben az orientáció változását vizsgálom a zsaluzat közelében és különbséget teszek merev (acél) és hajlékony (szintetikus) szálak között. A keresztmetszeten áthaladó szálak darabszámára mutatok be olyan számítási módszereket, amelyek a zsaluhatást és a szálak merevségét is figyelembe tudják venni.
by applying a BFGS quasi-Newton optimization procedure. Strong et al. [ 16 ] and Davis et al. [ 17 ] considered the fiberorientation influence on radiation heat transfer in their models.
There are generally two ways for measuring radiative
/solid conduction. Woo et al. [ 4 ] presented a more complicated heat transfer model of fibrous assemblies by considering fiberorientation and anisotropy, and the model is proved to be more accurate. However, the model contains so many parameters, which are complex