Experimental Comparison of the Bearing Capacity of GFRP Beams and 50% Recycled GFRP Beams

This manuscript investigates the possibility of using recycled glass fiber-reinforced polymer for the production of load-bearing elements in construction. Due to the increasing use of GFRP in the world, an increasing amount of waste is generated. The main objective of this research is to expand the use of composite materials in construction and, in particular, to examine the possibilities of original and recycled GFRP. Firstly, the basic characteristics of two different but very similar materials were determined using standard testing samples. Subsequently, experimental beam models were tested as a four-point bending beam model. The beam models used in this experiment were made of two types of materials, glass fiber reinforced polymer (GFRP) and recycled glass fiber-reinforced polymer (RGFRP). The experiments were conducted until the failure of the beam models. The test results are presented in the form of a force/displacement diagram, and the confirmation of the experimental results is shown by means of a numerical model of the beam. Both materials exhibited a very good strength-to-weight ratio, rendering them a suitable choice of material for load-bearing beam elements. Finally, the justification for recycling and the comparison of original and recycled material are presented in a dimensionless diagram. The comparison of these two materials provides some good insights for future research into GFRP beams. Doi: 10.28991/CEJ-2022-08-12-017 Full Text: PD

EKSPERIMENTALNA ANALIZA ZAJEDNIČKOG DJELOVANJA SAVIJANJA, POSMIKA I TORZIJE DRVENIH NOSAČA

Wood is an anisotropic material, i.e., it is composed of fibres that correspond better to normal stresses in the longitudinal direction or in the direction of fibres and poorly to stresses perpendicular to the fibres and to the longitudinal shear stresses. In practical situations it is better to avoid these stresses, although that is often very difficult. Because of this, the analysis of different interactions between shear and normal stresses perpendicular to the fibres is necessary. In this paper an experimental analysis of interaction of stresses from torsion and bending caused by an eccentric shear force was performed. The results are compared in a simple and practical way with the calculated values and the values from a linear numerical model. The paper analysed shear stresses parallel to the fibres and normal stresses perpendicular to the fibres and the results are shown numerically and by a force/displacement diagrams.Drvo je anizotropan materijal, odnosno, sastoji se od skupa vlakana koja bolje podnose normalna naprezanja u svom uzdužnom pravcu ili pravcu vlakana, a slabije okomito na pravac vlakana te posmično u uzdužnom pravcu. U praktičnim slučajevima potrebno je izbjegavati pojavu ovih nepovoljnih naprezanja, iako je to u pravilu teško izvedivo. Iz tog razloga, neizbježne su analize interakcija između svih posmičnih te normalnih naprezanja. U radu je eksperimentalno analizirana interakcija naprezanja od torzije i savijanja kroz djelovanje ekscentričnom poprečnom silom, a rezultati su na jednostavan i praktičan način uspoređivani s računskim vrijednostima te vrijednostima dobivenim linearnim numeričkim modelom. Naglasak je stavljen na posmična naprezanja paralelno vlaknima i normalna naprezanja okomito na vlakna, a rezultati su prikazani tablicom i dijagramima sila/pomak

ANALIZA DEFORMACIJA VIŠESLOJNIH NOSAČA OD STAKLOPLASTIKE, NA RAZLIČITIM MJESTIMA KONCENTRIRANOG UNOSA OPTEREĆENJA

We analyzed the load and deformation in hollow beams made from multilayered glass-fiber-reinforced polymer, specifically assessing deformation under concentrated load. We performed nonlinear numerical analysis on beam with rectangular cross-sections with set dimensions and material properties. Beams with three different spans were analyzed, loaded with two concentrated forces at varying distances between applied force and supports. As the force was increased, we assessed the deformation near the supports. These results are shown in dimensionless diagrams, where the ratio of the applied and initial force correlates to the ratio of deformation near the support to deformation near the mid-span.U radu se analiziraju opterećenja i deformacije kod šupljih nosača od pločaste višeslojne stakloplastike te ukazuje na problem koncentriranih sila. Nelinearna numerička analiza je provedena na nosaču pravokutnog poprečnog presjeka s unaprijed odabranim dimenzijama i karakteristikama materijala. Analizirani su nosači s tri različita raspona, a svaki je opterećivan dvjema koncentriranim silama, gdje je varirana udaljenost sila od oslonaca. Za postepeno povećanje sile praćena je promjena vrijednosti deformacije nad osloncima. Rezultati su prikazani bezdimenzionalnim dijagramima, odnosno, za omjer pripadne sile s početnom silom prati se omjer deformacije nad ležajem i progiba u polovini raspona

NUMERIČKI MODEL LOKALNOG GNJEČENJA NOSAČA OD STAKLOPLASTIKE

This paper presents an analysis of the deformations in hollow cross-sectional beams made of multilayer glass fiber-reinforced polymer at force application positions. A non-linear numerical analysis is conducted on a beam with a rectangular cross-section and familiar dimensions and material characteristics. Three beams with different spans that are all loaded with two concentrated forces are analyzed, where the distance of the forces from the supports is varied. The kneading deformations at the vicinity, where the two concentrated forces are applied, are monitored with regard to force increase. The results are shown in dimensionless diagrams, wherein the ratio of the actual and initial forces is related to the ratio of deformations at the force application points and mid-span.U radu se analiziraju deformacije kod šupljih nosača od višeslojnog polimera ojačanog staklenim vlaknima (stakloplastika) na mjestima djelovanja koncentriranih sila. Nelinearna numerička analiza je provedena na nosaču pravokutnog poprečnog presjeka s unaprijed odabranim dimenzijama i karakteristikama materijala. Analizirani su nosači s tri različita raspona, a svaki je opterećivan dvjema koncentriranim silama, gdje je varirana udaljenost sila od oslonaca. Za postepeno povećanje sile praćena je promjena vrijednosti deformacije gnječenja na mjestima opterećenja. Rezultati su prikazani bezdimenzionalnim dijagramima, odnosno, za omjer pripadne sile s početnom silom prati se omjer deformacije na mjestu opterećenja i u polovini raspona

EKSPERIMENTALNA ANALIZA NOSIVOSTI POLIMERA DOBIVENOG IZ RECIKLIRANOG MATERIJALA

The subject of this paper is experimental testing of a polymer and definition of the idealised stress/strain diagram, from which the modulus of elasticity can be easily defined. The analysis was conducted on polymer straps made of ethylene polymer of high density (HDPE). In this case the polyethylene (PE) was produced almost entirely from recycled material and that defines its cost. PE generally has high density and very good mechanical characteristics and resistance to chemicals. As a material it is used in production of reservoirs and containers for various purposes. This paper is trying to define the basic characteristics of polymers by observing their tensile strength, to propose an idealised stress/strain diagram and to define the numerical values of the modulus of elasticity. Also the intention is to create a tool which would enable the definition of the stress / strain diagram for any similar material and broaden the application and use of such types of materials.Predmet ovog rada je ispitivanje nosivosti polimera dobivenog iz recikliranog materijala i definiranje idealiziranog dijagrama naprezanje/deformacija, iz kojeg se lako može definirati modul elastičnosti. Analiza je provedena pomoću polimernih traka koje su izrađene od polimera etilena visoke gustoće (HDPE). U ovom slučaju polietilen (PE) je dobiven, gotovo u cijelosti, od recikliranog materijala, što u konačnici uvjetuje i njegovu cijenu. U pravilu je visoke gustoće i ima vrlo dobre mehaničke karakteristike i otpornost prema kemikalijama. Kao materijal prisutan je u proizvodnji rezervoara te posuda raznih namjena. U ovom radu nastoje se definirati osnovne karakteristike polimera kao materijala kroz rasteznu čvrstoću te predložiti idealizirani radni dijagram. Namjera je također kako bi ovaj rad postao alat kojim bi se mogao definirati dijagram naprezanje/deformacija za bilo koji drugi sličan materijal te otvoriti mogućnosti širokog spektra primjene

THE INFLUENCE OF EXCENTRICITY ON INNER FORCES IN TRUSSES

U radu je analiziran utjecaj ekscentriciteta kod rešetkastih nosača na unutarnje sile u štapovima. Analiza je provedena na konkretnom ravninskom rešetkastom nosaču s unaprijed odabranim dimenzijama nosača. Pretpostavka je da su štapovi ispune potpuno upeti u pojaseve kao i gravitacijski tip opterećenja. Usvojena je kombinacija zbroja vlastite težine i pokretnog opterećenja, koncentriranih u čvorovima gornjeg pojasa. Ekscentriciteti su zadavani u donjem pojasu, zatim gornjem pojasu te u oba pojasa. Vrijednosti ekscentriciteta su zadane kao omjer skraćenja štapa ispune i njegove duljine. Iz proračunom dobivenih rezultata, za kombinaciju opterećenja (stalno + promjenjivo), praćene su promjene vrijednosti momenta i uzdužnih sila na mjestima najvećih tlačnih sila, a to su: tlačni štap pojasa na sredini rešetke te tlačni štap ispune u prvom polju.This paper analyses the influence of eccentricity on inner forces in the elements of a truss grider. A specific planar truss with predefined dimensions was analysed. It’s assumed that web elements are equally rigidly connected to the chords and that the loads are gravitational. The load combination of self weight and one live load is used. Eccentricity is applied first in the lower chord, then in the upper chord and finally in both chords. Eccentricities are calculated as the ratio of the shortened length and the total length of the web element. From the results of the analysis, for the used load combination (self weight + live load) the changes in bending moments and axial forces were observed in the places of maximal compressive axial forces, that is the compressive top cord in the middle of the span and the compressive web element in the first field

NUMERICAL MODEL FOR LOCAL KNEADING OF GLASS FIBER-REINFORCED BEAM

This paper presents an analysis of the deformations in hollow cross-sectional beams made of multilayer glass fiber-reinforced polymer at force application positions. A non-linear numerical analysis is conducted on a beam with a rectangular cross-section and familiar dimensions and material characteristics. Three beams with different spans that are all loaded with two concentrated forces are analyzed, where the distance of the forces from the supports is varied. The kneading deformations at the vicinity, where the two concentrated forces are applied, are monitored with regard to force increase. The results are shown in dimensionless diagrams, wherein the ratio of the actual and initial forces is related to the ratio of deformations at the force application points and mid-span

Experimental analysis of the strength of a polymer produced from recycled material

Predmet ovog rada je ispitivanje nosivosti polimera dobivenog iz recikliranog materijala i definiranje idealiziranog dijagrama naprezanje/deformacija, iz kojeg se lako može definirati modul elastičnosti. Analiza je provedena pomoću polimernih traka koje su izrađene od polimera etilena visoke gustoće (HDPE). U ovom slučaju polietilen (PE) je dobiven, gotovo u cijelosti, od recikliranog materijala, što u konačnici uvjetuje i njegovu cijenu. U pravilu je visoke gustoće i ima vrlo dobre mehaničke karakteristike i otpornost prema kemikalijama. Kao materijal prisutan je u proizvodnji rezervoara te posuda raznih namjena. U ovom radu nastoje se definirati osnovne karakteristike polimera kao materijala kroz rasteznu čvrstoću te predložiti idealizirani radni dijagram. Namjera je također kako bi ovaj rad postao alat kojim bi se mogao definirati dijagram naprezanje/deformacija za bilo koji drugi sličan materijal te otvoriti mogućnosti širokog spektra primjene.The subject of this paper is experimental testing of a polymer and definition of the idealised stress/strain diagram, from which the modulus of elasticity can be easily defined. The analysis was conducted on polymer straps made of ethylene polymer of high density (HDPE). In this case the polyethylene (PE) was produced almost entirely from recycled material and that defines its cost. PE generally has high density and very good mechanical characteristics and resistance to chemicals. As a material it is used in production of reservoirs and containers for various purposes. This paper is trying to define the basic characteristics of polymers by observing their tensile strength, to propose an idealised stress/strain diagram and to define the numerical values of the modulus of elasticity. Also the intention is to create a tool which would enable the definition of the stress / strain diagram for any similar material and broaden the application and use of such types of materials

Određivanje modula elastičnosti stakloplastike

The subject of this paper is to determine the idealised stress-strain diagram (primal curve) as well as a numerical expression of a straight line and a parabolic curve for glass fibre reinforced polymers (GFRP). The intention is to create a tool, by which one could define the stress-strain diagram for any given glass fibre based on tensile strength. GFRP is a material that is increasingly being used in structures. Because of that we need to know some of its basic characteristics or of other similar composite materials, so as to be able to calculate these structures. This paper presents the modulus of elasticity determined by testing glass fibre reinforced polymer samples and a proposition of an idealised stress-strain diagram as well as a numerical determination of the modulus.Predmet ovog rada je određivanje idealiziranog dijagrama naprezanje-deformacija (primarna krivulja) te brojčana definicija pravca i krivulje drugog reda za stakloplastiku (GFRP). Namjera je, također, da ovaj rad postane alat kojim bi se mogao definirati dijagram naprezanje-deformacija za bilo koju drugu stakloplastiku na osnovu rastezne čvrstoće. Stakloplastika je materijal koji je ušao u širu primjenu u graditeljstvu, što zahtjeva i poznavanje određenih karakteristika same stakloplastike ili sličnih kompozitnih materijala, kako bismo mogli proračunati te konstrukcije. U ovom radu dan je modul elastičnosti za stakloplastiku određen ispitivanjima te prijedlog idealiziranog radnog dijagrama stakloplastike i računskog određivanja modula elastičnosti

Experimental analysis of combined action of bending, shear and torsion on timber beams

Drvo je anizotropan materijal, odnosno, sastoji se od skupa vlakana koja bolje podnose normalna naprezanja u svom uzdužnom pravcu ili pravcu vlakana, a slabije okomito na pravac vlakana te posmično u uzdužnom pravcu. U praktičnim slučajevima potrebno je izbjegavati pojavu ovih nepovoljnih naprezanja, iako je to u pravilu teško izvedivo. Iz tog razloga, neizbježne su analize interakcija između svih posmičnih te normalnih naprezanja. U radu je eksperimentalno analizirana interakcija naprezanja od torzije i savijanja kroz djelovanje ekscentričnom poprečnom silom, a rezultati su na jednostavan i praktičan način uspoređivani s računskim vrijednostima te vrijednostima dobivenim linearnim numeričkim modelom. Naglasak je stavljen na posmična naprezanja paralelno vlaknima i normalna naprezanja okomito na vlakna, a rezultati su prikazani tablicom i dijagramima sila/pomak.Wood is an anisotropic material, i.e., it is composed of fibres that correspond better to normal stresses in the longitudinal direction or in the direction of fibres and poorly to stresses perpendicular to the fibres and to the longitudinal shear stresses. In practical situations it is better to avoid these stresses, although that is often very difficult. Because of this, the analysis of different interactions between shear and normal stresses perpendicular to the fibres is necessary. In this paper an experimental analysis of interaction of stresses from torsion and bending caused by an eccentric shear force was performed. The results are compared in a simple and practical way with the calculated values and the values from a linear numerical model. The paper analysed shear stresses parallel to the fibres and normal stresses perpendicular to the fibres and the results are shown numerically and by a force/displacement diagrams