Interaction research into connection between threaded steel rod and glulam

Abstract

The article discusses the main methods for steel threaded rods pasted into timber. Single – threaded steel rod carrying capacity glued onto glulam (timber cross section – 100 x 100 mm, threaded rod – M12 and M16) has been experimentally determined. Behaviour based on the experimental results of two different methods for pasting rods into timber has been summarized: the first threaded steel rod was glued into 4 mm bigger diameter hole while the second – rod chased into 2 mm smaller diameter hole. The conducted experiment used 800 mm length glulam beams; threaded steel rods were glued to both ends of specimens (equal theoretical carrying capacity). The experiment in the tension of both ends was carried out. The obtained results were compared with theoretical expressions submitted in EC 5 – 1 – 1:2005 and STR 2.05.07:2005. The main dependences of geometrical parameters and carrying capacity have been provided. The main collapse forms of specimens and manufacturing defects having influence on the final carrying capacity and behaviour of the joint have been observed. Using the first method, a failure in the pasted rod occurs suddenly when timber splits along the fibre; in the second case, a failure is plastic when timber is compressed under thread. Additional experiments must be carried out using the first technology increasing the class of the strength of the pasted rod as under the maximum length of paste, in all cases, failure in the pasted rod occurred when a steel bar cracked. Along with an increase in the diameter of the rod, the dispersion of the results of the affixed slender part is increasing. Maximum variation in the results of applying the first method is 10%, whereas the second method of attaching makes 50%. Compared to the first method of attaching, the results of theoretical bearing capacity indicate that tests have an adequate margin which is equal to or is more than 2,0. A comparison of the second method of attaching results to theoretical bearing capacity makes clear that the experimental results of the tests have too low safety factor and in some cases are less than 1.0. This is due to the fact that the counting of attaching technology in some cases must be based on local compressed timber strength. The experimental study of two different methods for attaching steel bars reveals that the first method can be used in design practice considering both documents STR 2.05.07:2005 and EC 5-1-1:2005. The second method of attaching must be developed to ensure smooth rod surface coating adhesive. Attaching the second method should also be created in the exact form corresponding to the disintegration of the calculation model.

Article in Lithuanian.

Jungties tarp įklijuoto plieninio sriegtojo strypo ir medienos elgsenos tyrimas

Santrauka. Straipsnyje aptariami pagrindiniai plieninių sriegtųjų strypų įklijavimo medienoje metodai. Eksperimentais nustatytos pavienių plieninių sriegtųjų strypų (M12 ir M16), įklijuotų medienoje, jungčių laikomosios galios. Apibendrinta dviejų skirtingų įklijavimo metodų (pirmasis – strypas įklijuojamas į 4 mm didesnio skersmens kiaurymę; antrasis – strypas įsriegiamas į 2 mm mažesnio nei strypas skersmens kiaurymę) elgsena remiantis eksperimentinių tyrimų rezultatais. Pagrindiniam eksperimentui naudoti klijuotosios medienos elementai (skerspjūvio matmenys – 100×100, ilgis – 800 mm), kurių galuose lygiagrečiai su medienos pluoštu buvo įklijuoti sriegtieji plieniniai strypai. Atliktas abipusis tempimo bandymas apkrovą perduodant strypams. Eksperimentinių tyrimų rezultatai lyginami su teorinės laikomosios galios skaičiavimais, atliktais pagal Lietuvos ir Europos medinių konstrukcijų projektavimo normų taisykles. Pateiktos jungties laikomosios galios ir geometrinių parametrų priklausomybės. Aptartos pagrindinės bandinių suirimo formos ir gamybos netikslumai, turėję įtakos jungties laikomajai galiai.

Reikšminiai žodžiai: medienoje įklijuoti strypai, įtempių pasiskirstymas medienoje, medienos jungtis.

First Published Online: 16 May 2013

Keyword : glued-in rod, wood, timber joint, test method