Testing and analysis of walls strengthened with FRP

U radu je opisana usporedba laboratorijskih i terenskih ispitivanja na posmik zidova ojačanih karbonskim (C) trakama i staklenim (G) mrežicama u polimerima s rezultatima proračunskih modela za zidove s FRP-om. Rezultati ispitivanja na zidovima od nove i stare pune opeke pokazali su povećanje posmične nosivosti i graničnog pomaka - najviše za horizontalne i horizontalno-vertikalne epoksidom zalijepljene trake te mrežice u modificiranom cementnom mortu, a najmanje za dijagonalne trake zbog odstupanja sa zida. ACI i CNR računski modeli pokazali su najbolje podudaranje s eksperimentima.Laboratory and in-situ shear tests of walls strengthened with Carbon FRP (Fiber Reinforced Polymer) strips and Glass FRP grid were compared to the results of different calculation models for masonry with FRP. Tests on new and old solid brick specimens showed an increase in shear strength and ultimate displacement. The best results were obtained with horizontally and horizontally-vertically epoxy-bonded strips and modified cement mortar grid configurations, worse with diagonal strips due to peeling failure. ACI and CNR calculation approaches showed the best agreement with experimental results

Effects of strengthening brick masonry walls with FRP

Področje raziskovanja doktorske disertacije je potresna odpornost zidanih stavb, ojačenih s FRP (fibre reinforced polymer - z vlakni armirani polimer) in FRM (fibre reinforced mortar - z vlakni armirana malta). V sklopu preiskav smo načrtovali in in-situ preskušali več sistemov ojačevanja starih opečnih zidov ter novih kamnitih zidovih v laboratoriju. Učinkovitost povezave zidovja in kompozitnih oblog pri strižni obremenitvi smo za vse sisteme dodatno preiskovali na manjših opečnih vzorcih v laboratoriju. Rezultati strižnih preiskav v ravnini zidov so pokazali, da je ojačevanje s horizontalnimi karbonskimi trakovi na epoksidnem lepilu ter stekleno mrežico v modificirani cementni malti, učinkovito, ojačitev z diagonalnimi karbonskimi trakovi pa manj. Preiskave strižnega stika so pripeljale do spoznanja, da je nujna kvalitetna priprava podlage in izvedba dobrega sidranja koncev trakov. Cilj izvedbe lastnih eksperimentalnih preiskav ter poglobljene študije tega znanstvenega področja je bil ovrednotenje obstoječih računskih modelov, izpeljava izboljšanega modela ter integracija tega v računalniški program za računanje potresne odpornosti zidanih stavb. Nelinearna potresna analiza stavbe z etažnim mehanizmom s programom SREMB, izvedena na osnovi novorazvitega računskega modela, kaže, da lahko za neojačano stavbo dobro določimo potresno odpornost, ki je v primerjavi z okvirnim mehanizmom TREMURI ravno za toliko višja, kot je izboljšan nov računski model. Dodatno lahko z novim računskim modelom s programom SREMB preračunamo tudi zgradbe, katerih zidovi so ojačeni s poljubnimi ojačitvami s FRP/FRM materiali - horizontalnimi, vertikalnimi, diagonalnimi in vsemi možnimi kombinacijami.The scope of doctoral dissertation is research of the seismic resistance of masonry buildings, reinforced with FRP (fiber reinforced polymer) and FRM (fiber reinforced mortar). Several systems for strengthening of old brick walls were tested in-situ and new stone walls in the laboratory. The efficiency of the bond of the brickwork and composite coverings at shear forces for all systems were further investigated in small clay samples in the laboratory. The results of in-plane shear tests have shown good performance of strengthening by horizontal reinforcing carbon strips and glass mesh in a modified cement mortar, however reinforcement with diagonal carbon strips was less effective. Investigations of shear contact on small brick samples with FRP/FRM cover led to the conclusion that for the efficient strengthening the good basis preparation and sound anchoring of the ends of the strips are necessary. The objective of the own experimental investigations and in-depth study of this scientific field was the evaluation of the existing calculation models and the integration of improved model in the software for computation of seismic resistance of masonry buildings. Nonlinear seismic analysis of the building performed based on newly developed computational model, shows that for the unreinforced building the earthquake resistance can be determined well, just as high as the TREMURI framework mechanism because the new calculation model has been improved. In addition, the new calculating model in SREMB can also be used to calculate buildings strengthened with FRP / FRM materials, horizontal, vertical, diagonal and all possible combinations