Edo Wallner
2oo4/1
AR
Slika 1: Ojačitev natezne cone z lamelami iz steklenih vlaken (FRP).
Strengthening the bending zone with glass fibre lamellas (FRP).
Slika 5: Simulacija ojaèitve natezne cone z lamelami iz steklenih vlaken (FRP).
Simulation ofstrengthening the bending zone with glass fibre lamellas (FRP).
Slika 4: Dolepljenje lesa brez predkrivljenja.
Additional glued wood without pre-bending.
Slika 2: Simulacija lezenja lesa pri dolgotrajni obtežbi.
Simulation ofcreeping in wood under long-term loads.
Slika 5: Dolepljenje lesa s predkrivljenjem.
Additional glued wood with pre-bending.
AR
2oo4/1
Edo Wallner
OJAČITVE LESENIH NOSILCEV REINFORCEMENT OF WOODEN BEAMS
raziskava, research
povzetek
Načinov kako ojačamo lesene nosilce je več in so odvisni predvsem od trenutne situacije in možnosti. Lesen nosilec lahko ojačamo še pred montažo, lahko pa nosilec ojačujemo šele po tem, ko je nosilec že vgrajen in celo obremenjen.
Za simulacijo razvoja časovno odvisnih deformacij in napetosti v lesu smo izdelali računalniški program Scout, s katerim je mogoče simulirati dolepljenje lamel iz različnih materialov in celo tehnologijo predkrivljenja.
Pri materialih lahko simuliramo poljuben material, tudi take z nelinearnim odzivom vključno z lezenjem. V okviru raziskave smo naredili nekaj primerjalnih simulacij, ki smo jih uporabili za preverjanje programa. Numerični rezultati programa Scout in eksperimentalni podatki dosegljivi iz literature so se razmeroma dobro ujemali.
Dokazali smo, daje dolepljenje natezni lamel vsekakor koristno in, da s prednapenjanjem po tehnologiji predkrivljenja še dodatno povečamo učinek ojačitve. S tem smo dokazali, daje za enak učinek potrebno manj materiala.
summary
There are numerous methods used for strengthening wooden beams, depending on given circumstances and possibilities. Wooden beams can be strengthened before or after assembly, when the beam is already in place and under loads.
To stimulate the development of time-conditioned deformations and stress in wood we produced the computer programme Scout, which facilitates simulation of additional glued lamellas of various materials and even pre-bending technology.
When simulating materials we can specify any given material, even such with non-linear response, including creeping. In the research we conducted several comparative simulations, and used them to test the programme. Numerical results from the programme and experimental data gatheredfrom literature were relativelysimilar.
We proved that additional glued lamellas were beneficial against stretching and that pre-stressing done with the pre-bending technology actually enhanced the effect of strengthening. Therefore we proved that the same effect could be achievedwith less material.
doseženi cilji, namen in rezultati
Glavni cilj naše raziskave je bil preveritev možnosti ojačevanja nosilcev izdelanih iz lesa slovenskih iglavcev. Z namenom, da pocenimo raziskavo, smo upogibne obremenitve prostoležečih nosilcev simulirali s programom Scout. Rezultati analize so pokazali, da tako ojačani leseni prerezi dosežejo tudi 50% večjo upogibno odpornost. Uporaba iste kombinacije materialov in sistema predkrivljenja, s katerim dosežemo prednapetje armature, pa lahko doseže celo za 75% večjo upogibno odpornostnosilcev.
intentions, goals and results
The main research goal was to check possibilities for strengthening load-bearing wooden beams produced from domestic coniferous timber. To diminish research costs we simulated bending of simple beams with the programme Scout. Results of the analysis showed that wooden sections strengthened in the described manner increase bending resilience by more than 50 %. Use of the same combination of materials andpre-bending systems, which help in achievingpre-stressed reinforcement, can increase bending resilience of beams by more than 75 %.
problematika v arhitekturi, umestitev obravnavane teme v te tokove in njen pomen
V arhitekturi pogosto naletimo na primere, ko se namembnost objektov menja ali pa, daje obstoječa konstrukcija preslabotna inje potrebna rekonstrukcija, kjer lahko uporabimo prikazane principe. Prav tako lahko to znanje uporabimo tudi pri novogradnjah, kjer se zahteva minimalne prereze konstrukcijskih elementov.
architectural issues, positioning the topic in ongoing debate and its' significance
In architecture we often encounter cases where the use of buildings changes or where the structure is too weak and demands reconstruction and can thus implement the presented principles. Similarly the knowledge can be used even for new developments, in which minimal sections of structural elements are demanded.
ključne besede
konstrukcija, upogib, lesen lameliran lepljen nosilec, tehnologija predkrivljenja
key words
structure, bending, glued laminated wooden beam, technology of prebending