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This paper presents the results of research conducted within R&D project. The primary goal was to apply the current state of the art technology in aluminium to a timber-based frames, but also to improve the energy performance of the building envelope and create environmentally friendly product, which physical, structural and aesthetic performances are equal to or even better than equivalent aluminium systems. The developed TimberCW is an innovative structurally glazed curtain wall system entirely comprised of laminated timber profiles incorporated in a fully prefabricated unitised curtain wall design, where glass panes are bonded by the structural silicone to timber frames. While most current timber curtain wall systems are stick designs, combined with aluminium elements, this new concept introduces timber split mullions and entirely eliminates aluminium structural members, whilst maintaining high weathertightness performance. In order to retain thin cross sections, as they are common for aluminium design, specialised corner connections in timber frame and stainless-steel bracketry has been developed and laboratory tested. Comparative energy efficiency analysis and condensation risk assessment of the TimberCW vs fully unitised aluminium systems of identical overall geometry and structural performance are presented. Full scale laboratory testing has been undertaken and certification obtained, proving the TimberCW concept suitable for project application.

The roof of the Zagreb Cathedral, dating from the general reconstruction in 1890-ties, withstood the 2020 earthquake in Croatia with remarkably good resilience. However, the restructuration project after the quake initiated extensive activities on the condition survey and consideration of possible measures for ensuring the future longevity, structural stability, and seismic resistance of the structure. The assessment encompassed the determination of wood species, anatomical structure, hygrotechnical conditions, as well as physical, mechanical, and biological properties of wood and load-bearing capacity of timber. It was demonstrated that visual grading and density measurements on drill cores proved adequately chosen main inputs for determining mechanical properties. The (quasi) nondestructive testing (NDT) - stress-wave, screw withdrawal and resistance drilling - proved useful additional methods yet fully effective only in combination with microscopic evidence on cores. A newly developed method of fairly invasive but completely re- constructive sample withdrawal of 50×50×800 mm beams yielded the MOEstat and standard test values on small clear samples (bending, MOEstat, shear ǁ and compression ǁ). NDT tests and small clear samples varied in conformity and measurement uncertainty but usefully complemented the main results and indicated the required corrections in mechanical classification. Special attention was paid to the detailed survey and analysis of timber joints and the consequent stability of the structure in the future. Dead loads, snow loads, and wind loads were considered in structural analysis models. Also, the history of seismic responses was also analysed. Such analyses form a sound base for the technical design of reinforcements as well as necessary repair and reconstruction measures of the roof structure.

Hrastovina predstavlja izuzetno vrijedno turopoljsko prirodno bogatstvo, a njezina uporaba za gradnju je pogotovo važna zbog izvrsnih mehaničkih svojstava i visoke postojanosti prema vremenskim djelovanjima i biološkoj razgradnji, što osigurava dugotrajnost drvenih građevina ili dijelova njihovih konstrukcija. Kakogod, i ovako visoka trajnost zahtijeva tehnički nadzor i mjere održavanja, pogotovo na građevinama koje predstavljaju spomeničku baštinu. Pristup ocjeni stanja povijesnog drva je specifičan kako po metodologiji, tako i po interpretaciji rezultata, jer o njemu ovisi projektiranje nosivosti i funkcionalnosti klasičnih drvenih konstrukcija. Primjeri analize stanja krovišta baroknih crkava u nekim turopoljskim mjestima demonstriraju osnovne korake u ocjeni stanja povijenoga drva: identifikaciju vrste drva, mjerenje fizičkih i mehaničkih svojstava drva radi izračuna nosivosti elemenata, analizu biološke razgradnje i iskaz zaostalog nosivog presjeka elemenata, te ocjenu geometrijske pravilnosti i tehničke ispravnosti konstrukcije i pojedinih spojeva. Odabrani rezultati trebaju prikazati s kojom se brigom i predviđenim zahvatima obnove proučava stanje hrastovih krovnih konstrukcija u postupcima potresne obnove nakon 2020. godine.

Heat treated wood (HTW) is successfully applied for floorings due to its better moisture resistance, increased dimensional stability, and uniform colour change to darker, brownish colours. The aim of this work was to define the hygroscopic range and equilibrium moisture content at ambient conditions of heat treated wood of two wood species – ash and beech. Material was treated at two temperature levels, 190 and 210 °C, and the properties were compared with native wood. The reduction in dimensional changes is expressed by volumetric shrinking and Anti Shrink Efficiency (ASE). Additionally, parquet elements were made out of such HTW, oil-impregnated and waxed, and subsequently tested for water vapour and liquid water permeability. Shrinking gradients of HTW were not reduced in comparison with native beech wood, but the absolute reduction in water uptake resulted in cca 50 % lower EMC values and up to cca 60 % improved ASE values. Surface treatment further improved the hygroscopic properties of HTW.

Hardness and density of the wood are considered to be among the most important technical properties of wood flooring. There are standardized methods for determining specified properties, but in factory conditions they are rarely used. The reason is that they require expensive specialized equipment, a large number of test samples, trained staff, and they are relatively long lasting. For these reasons, there was a need for simpler, faster and less expensive method to determine the above mentioned properties of wood. This paper explores the possibility of substitution of the standard methods for determining Brinell hardness with the method of the relative size of the impression (RSI), and also the possibility of substitution of standard test methods for determine wood density (ISO 3131: 1975) with method of measuring the mass of floor elements whose volume is known. The aim of the research is finding a scientifically based, simpler, faster and cheaper ways of determining the aforementioned properties of wood. Innovative methods have proven to be very simple and useful with satisfactory results for practical use.

U radu je dan pregled izlaganja i komentari sa skupa o drvnim premazima "Enhancing Service Life" održanom 2006. godine u Pragu.

Posljednjih godina intenzivno se radi na razvoju metoda poboljšanja svojstava i trajnosti drva i sustava prevlaka-drvo. Svojstva drva poput dimenzionalne stabilnosti, vodoodbojnosti, otpornosti prema biološkoj razgradnji te otpornosti prema ultraljubičastoj i vidljivoj svjetlosti, pa čak i mehanička svojstva drva mogu se poboljš ati modifikacijskim (toplinskim i kemijskim) postupcima. Nadalje, uvođenjem novih materijala za površinsku obradu s nanočesticama može se povećati vodoodbojnost, a dodatno i otpornost prema ultraljubičastom zračenju. Postupci toplinske modifikacije i acetilacija u inozemstvu se već komercijalno primjenjuju, dok se djelotvornost ostalih pokusnih postupaka, kao što je obrada površine nano premazima, tek treba potvrditi u praktičnoj primjeni. Zbog poboljšanih svojstava drvo ostaje konkurentan materijal u graditeljstvu, posebno za drvena pročelja, ograde, prozore i vrata, vrtni namještaj, ali i kao materijal za podove i namještaj u interijeru.

Investigations of the weathering of wood very often involved observations of structural changes using SEM (Scanning Electron Microscopy) analysis. Microscopic observations can not quantify the degradation process and are not sensitive enough in detecting changes during early stages of photodegradation (unlike colour measurements and spectrophotometry). However, SEM technique can be combined with the thin strip method, where highly accurate and reliable tensile strength measurements on microtomed surface sections are corroborated by microscopic evidence about the consequences of photo-induced surface degradation.

Wood in exterior conditions undergoes a series of chemical and physical changes that impair its aesthetic appeal and durability. The cladding of the houses is a particularly challenging application means because of the high aesthetic, thermal, other physical and technical demands over a long period of decades, sometimes centuries in use. In order to keep the functional properties of wood unchanged in a long service life, a variety of protective measures may be employed. Physical protection is marked as the most important way to keep the harmful effects of ultraviolet light and precipitation away. Design detail of wood products in facades, as well as their assembly means, are considered from the viewpoint of their durability. Chemical protection should generally be avoided, i.e. restricted to a small number of cases when it simply can not be avoided, but surface finishing plays a major aesthetic and technical role in designing and maintaining the wooden facades.