RELIABILITY OF TIMBER STRUCTURES EXPOSED TO FIRE

Until recently, the fire resistance of buildings was based on the ISO standard curve. ISO standard curve used by the current norm is too simple, unrealistic and lead to uneconomic situations with no guarantee of security proportional to the invested money. Unlike the fire design of the steel, concrete or composite structures, methods for fire design of timber structures have been greatly simplified. Generally, it is not necessary to check the reduction of strength in the residual section because each increase of temperature is considered small and it is ignored. Global fire safety concept of timber structures is presented according to the recommendations from Eurocode norms. Special attention was given to natural fire design with two different methods of parametric exposure which are given in EN1995-1-2.This paper presents reliability analysis of a glulam beam in a case of fire. The limit-state functions for maximum bending stress of glulam beam in fire conditions are formed. Reliability indexes are obtained from the limit state of the beam exposed to 30 min fire. Reliability index in the Eurocodes (reliability class RC2) compared to the calculated reliability indexes obtained by the methods of reduced strength and effective section were described

Testing composite wood and lightweight concrete girders

Opisuju se rezultati ispitivanja nosivosti i uporabljivosti spregnutih nosača drvo-lagani (EPS) beton. Predstavlja se novo, originalno kontinuirano sredstvo za sprezanje i utvrđuju se prednosti njegove primjene pri sprezanju laganog betona i drva u odnosu na diskretna sredstva za sprezanje. Budući da ni u jednoj zemlji ne postoji propisima određena metoda proračuna dana je pojednostavljena metoda proračuna kao prijedlog u okviru STEP/EUROFORTECH inicijative EU Comett programa.Results obtained by testing bearing capacity and usability of composite girders made of wood and light-weight concrete, are presented. A new and original method for obtaining composite action is presented and its advantages in ensuring composite action of lightweight concrete and wood, as related to discrete means for providing composite action, are determined. As no country has specified in appropriate regu-lations a mandatory calculation method, the author presents a simplified calculation method as a pro-posal within the framework of the STEP/EUROFORTECH initiative of the EU Comett Program

Testing composite wood and lightweight concrete girders

Opisuju se rezultati ispitivanja nosivosti i uporabljivosti spregnutih nosača drvo-lagani (EPS) beton. Predstavlja se novo, originalno kontinuirano sredstvo za sprezanje i utvrđuju se prednosti njegove primjene pri sprezanju laganog betona i drva u odnosu na diskretna sredstva za sprezanje. Budući da ni u jednoj zemlji ne postoji propisima određena metoda proračuna dana je pojednostavljena metoda proračuna kao prijedlog u okviru STEP/EUROFORTECH inicijative EU Comett programa.Results obtained by testing bearing capacity and usability of composite girders made of wood and light-weight concrete, are presented. A new and original method for obtaining composite action is presented and its advantages in ensuring composite action of lightweight concrete and wood, as related to discrete means for providing composite action, are determined. As no country has specified in appropriate regu-lations a mandatory calculation method, the author presents a simplified calculation method as a pro-posal within the framework of the STEP/EUROFORTECH initiative of the EU Comett Program

Expert system for checking efficiency of water management planning activities

U radu su prikazane osnove razvoja ekspertnog sustava za ocjenu uspješnosti planiranja u gospodarenju vodama prema modelu SPGV (savjetnik za planiranje u gospodarenju vodama). Primjena modela osigurava uspješnije planiranje u gospodarenju vodama. Može se primijeniti za ocjenu uspješnosti provođenja procesa planiranja tijekom izrade planske dokumentacije u području gospodarenja vodama, isto tako i za ocjenu već provedenog procesa planiranja odnosno gotovog planskog dokumenta.The development of an expert system for estimating efficiency in water management planning by using the WMPC model (Water Management Planning Consultant) is briefly presented in the paper. The model enables a highly advanced planning of water management activities. It can be used for estimating efficiency of planning during elaboration of planning documents relating to water management, and also for assessing a completed planning process, i.e. the final planning document

Identification of water surfaces on satellite photographs by neural network

U radu je opisana jedna od mogućnosti utvrđivanja obuhvata vodenih površina sa satelitskog snimka korištenjem neuralne mreže. Usporedba s ručnom klasifikacijom na ispitivanom području pokazalo je vrlo dobro slaganje rezultata. S obzirom na to da postoje otvorene mogućnosti daljnjih unapređenja većine elemenata te unapređenja ukupnog koncepta, autori su uvjereni da bi se mogli dobiti još bolji i pouzdaniji rezultati te bi svakako bilo uputno nastaviti istraživanja na tom planu.A possibility of using neural networks to determine the extent of water surfaces shown in satellite photographs, is described in the paper. Comparison with manual classification in the same area shows a very good correspondence of results. As there are ample possibilities for developing an overall concept and most of its elements, authors believe that current results could be improved and made more reliable and, consequently, that further investigations in this fields are highly warranted

Composite materials based on wood and polymers

U proteklih nekoliko godina, stvaraju se novi materijali na osnovi drva i polimera – drvoplastika (Wood Plastic Composites - WPC). Drvoplastika se definira kao kompozitni materijal koji sadrži drvo (u bilo kojem obliku) i termoplastične polimere ili termostabilne polimere. U radu se prikazuje povijesni pregled uporabe drvoplastike, struktura i način proizvodnje, tipični elementi od kompozitnih materijala, fizikalna i mehanička svojstva, te prednosti i mane ovog materijala.New materials based on wood and polymers or woodplastics (Wood Plastic Composites - WPC), have been developed over the past several years. The woodplastics is defined as a composite material which contains wood (in any form) and thermoplastic or thermostable polymers. The authors present a historic overview of the use of woodplastics, its structure and production method, typical elements of these composite materials, their physical and mechanical properties, and advantages and shortcomings of this material

Classification of timber

Opisuje se trenutno stanje razredbe drvene građe u nas u odnosu na prilagodbe sustavu klasifikacije prema EN 338. Istaknuto je da rezultati brojnih ispitivanja drvene građe provedenih u nas pokazuju da su vrijednosti nekih mehaničkih svojstava ispitane građe veće od onih prema EN 338 s odgovarajućim modulom elastičnosti. Razmatra se i prijedlog za poboljšanje koji se može primijeniti u prijelaznom razdoblju, a zasnovan je na upotrebi neuralne mreže kao pomoćne tehnike.The current classification of timber in our country is described in the light of approximation to the classification system according to EN 338. It is emphasised that results obtained by numerous timber tests conducted in our country show that the values of some mechanical properties of tested timber are higher when compared to those based on EN 338, for the similar modulus of elasticity. The proposal is given for improvement that can be applied in transition period, based on the use of neural network as an accessory technique

Composite materials based on wood and polymers

U proteklih nekoliko godina, stvaraju se novi materijali na osnovi drva i polimera – drvoplastika (Wood Plastic Composites - WPC). Drvoplastika se definira kao kompozitni materijal koji sadrži drvo (u bilo kojem obliku) i termoplastične polimere ili termostabilne polimere. U radu se prikazuje povijesni pregled uporabe drvoplastike, struktura i način proizvodnje, tipični elementi od kompozitnih materijala, fizikalna i mehanička svojstva, te prednosti i mane ovog materijala.New materials based on wood and polymers or woodplastics (Wood Plastic Composites - WPC), have been developed over the past several years. The woodplastics is defined as a composite material which contains wood (in any form) and thermoplastic or thermostable polymers. The authors present a historic overview of the use of woodplastics, its structure and production method, typical elements of these composite materials, their physical and mechanical properties, and advantages and shortcomings of this material

The behavior of the cyclic loaded joint in the corner of a timber frame made of glued-in rods

Prilikom projektiranja konstrukcija u potresnim područjima, često se zahtijeva rješenje kojim se postiže povećanje krutosti i nosivosti na seizmička opterećenja uz minimalno povećanje mase konstrukcije. Trenutna istraživanja Sveučilišta u Zagrebu, koja se obavljaju u suradnji sa Sveučilištem u Ljubljani, razvijaju posebnu vrstu visokoduktilnog hibridnog panela sastavljenog od drvenog okvira s ispunom od nosivog lameliranog stakla, koji, pored nosivosti i krutosti, nudi i visoki stupanj disipacije potresne energije. Iako seizmičko ponašanje ovog konstruktivnog elementa značajno ovisi o dimenzijama pojedinih segmenata panela, kao i fizikalnim karakteristikama materijala, sama nosivost pak, ponajviše je definirana ponašanjem spoja prečke i stupa okvira. Prethodnim istraživanjima određen je optimalni način spajanja – ulijepljenom šipkom. U radu su predstavljena daljnja istraživanja, provedena u sklopu HRZZ projekta VETROLIGNUM. Ispitani su ciklički opterećeni uzorci s različitim promjerima šipki i mjestima upinjanja elemenata stupa te su predstavljeni rezultati i dan kritički osvrt.During the design of structures in seismic areas, solution which provides increase of rigidity and seismic capacity with minimal increase of structural mass is often required. Current research at the University of Zagreb, performed in cooperation with the University of Ljubljana, is leading to the development of high-ductility hybrid panel made of timber frame with laminated glass infill, which, in addition to strength and stiffness, is also characterized by high level of seismic energy dissipation. Although seismic behavior of this element significantly depends on dimensions of individual panel segments, as well as on material physical characteristics, bearing capacity is predominantly defined by behavior of girder-column joint. Previous research has determined the optimal type of joint – with glued-in rod. Further research, done under CSF project VETROLIGNUM, is presented in paper. Samples with different rod diameters as well as with different position of column fixed restraint were tested under cyclic loading. Results are presented and discussed

Classification of timber

Opisuje se trenutno stanje razredbe drvene građe u nas u odnosu na prilagodbe sustavu klasifikacije prema EN 338. Istaknuto je da rezultati brojnih ispitivanja drvene građe provedenih u nas pokazuju da su vrijednosti nekih mehaničkih svojstava ispitane građe veće od onih prema EN 338 s odgovarajućim modulom elastičnosti. Razmatra se i prijedlog za poboljšanje koji se može primijeniti u prijelaznom razdoblju, a zasnovan je na upotrebi neuralne mreže kao pomoćne tehnike.The current classification of timber in our country is described in the light of approximation to the classification system according to EN 338. It is emphasised that results obtained by numerous timber tests conducted in our country show that the values of some mechanical properties of tested timber are higher when compared to those based on EN 338, for the similar modulus of elasticity. The proposal is given for improvement that can be applied in transition period, based on the use of neural network as an accessory technique