Multiplicative Decomposition Based FDEM Model for Membrane Structures

A finite strain large displacement model for membrane structures based on the combined finite-discrete element method (FDEM) has been developed. The model is implemented in the open source FDEM package - Yfdem. The paper also presents benchmark tests and numerical results

Reliability of steel structures in case of fire

Na primjeru čelične krovne konstrukcije sportske dvorane „Spaladium“ u Splitu prikazan je novi način proračuna nosive konstrukcije na djelovanje požara u velikim zatvorenim prostorima sukladno Eurokodu. Modelom zona dobiveni su odnosi temperatura-vrijeme u zatvorenom prostoru i to za dvije požarne situacije: požar na borilištu i požar na tribinama. Na temelju krivulja temperatura-vrijeme u nosivim elementima čelične konstrukcije analizirana je pouzdanosti krovne konstrukcije.A new method for analyzing fire resistance of load bearing structures in big indoor spaces, based on Eurocode, is presented through case study of the steel roof structure of the Spaladium Sports Hall. The temperature-time relationships for indoor space are obtained by the zone model, and this for two fire situations: fire in the arena, and fire on the grandstand. The reliability of the roof structure is analyzed based on temperature-time curves in load-bearing elements of the steel structure

A New Algorithm for Dynamic Analysis of Thin Plates in the Combined Finite-Discrete Element Method

This paper presents a new numerical algorithm for a dynamic analysis of thin plate structures based on the combined finite-discrete element method (FDEM). A nonlinear analysis of thin plates subjected to static or dynamic load has been provided. The model uses 3-noded triangular finite elements and is implemented in the open source FDEM package - Yfdem. The performance of the new model on simple benchmark tests is presented

Reference wind velocity - influence of averaging period

Prikazani su rezultati analize promjenjivosti brzine vjetra na meteorološkoj postaji Novalja u razdoblju 1995.-1999. Posebno je ispitana korelacija brzina vjetra osrednjenih u 10-minutnim i satnim intervalima, te je predložena metodologija objedinjavanja svih raspoloživih podataka mjerenja smjera i brzine vjetra neovisno o intervalu osrednjavanja. Analiza strujanja pokazala je da turbulentna komponenta brzine vjetra nije dobro reprezentirana 10-minutnim srednjacima brzine.Results obtained by analyzing variability of wind velocity at the Novalja weather station in the 1995 - 1999 period are presented. The correlation between wind velocity values averaged in 10-minute and hourly intervals is analyzed, and a methodology for unifying all available information for measuring direction and velocity of wind is proposed, regardless of the averaging interval. The analysis of currents has shown that turbulent component of the wind velocity is not well represented by 10-minute average velocity periods

Fire safety of steel structures

Prikazana je analiza djelovanja različitih slučajeva realnog požara za skladišnu halu. Primjenom modela zona za različita požarna opterećenja dobivene su temperaturne krivulje u funkciji vremena, koje su uzete kao djelovanje na nosivu čeličnu konstrukciju. Na temelju dobivenih temperaturnih krivulja modelirano je provođenje topline kroz osnovni materijal konstrukcije, te je utvrđen stupanj njene sigurnosti. Istraživanja se provode u okviru NAD-a (National Application Document).The analysis of various cases or real fire impact on a warehouse is presented. Temperature curves were obtained as a function of time by means of the zone model established for different fire loads. These curves were then used as actions influencing the load bearing steel structure. Based on such temperature curves, the passage of heat through the basic material of the structure was modeled, and the safety level of the structure was determined. These studies are conducted in the scope of the NAD (National Application Document)

Reference wind velocity - influence of averaging period

Prikazani su rezultati analize promjenjivosti brzine vjetra na meteorološkoj postaji Novalja u razdoblju 1995.-1999. Posebno je ispitana korelacija brzina vjetra osrednjenih u 10-minutnim i satnim intervalima, te je predložena metodologija objedinjavanja svih raspoloživih podataka mjerenja smjera i brzine vjetra neovisno o intervalu osrednjavanja. Analiza strujanja pokazala je da turbulentna komponenta brzine vjetra nije dobro reprezentirana 10-minutnim srednjacima brzine.Results obtained by analyzing variability of wind velocity at the Novalja weather station in the 1995 - 1999 period are presented. The correlation between wind velocity values averaged in 10-minute and hourly intervals is analyzed, and a methodology for unifying all available information for measuring direction and velocity of wind is proposed, regardless of the averaging interval. The analysis of currents has shown that turbulent component of the wind velocity is not well represented by 10-minute average velocity periods

Reduction of Postfire Properties of High-Strength Concrete

This paper presents an experimental study of behaviour of high-strength concrete at high temperature. Reduction of the mechanical properties of concrete was determined starting from the period when the concrete specimens were heated to the maximum temperature and cooled down to ambient temperature and the additional 96 hours after the initial cooling of the specimens. The study includes determination of compressive strength, dynamic and secant modulus of elasticity, and stress-strain curves of concrete specimens when exposed to temperature level up to 600°C. The study results were compared with those obtained from other studies, EN 1994-1-2 and EN 1992-1-2. Tests point to the fact that compressive strength of concrete continues to reduce rapidly 96 hours after cooling of the specimens to ambient temperature; therefore indicating that the mechanical properties of concrete have substantial reduction after being exposed to high temperature. The study of the dynamic and secant modulus of elasticity shows that both of the properties are reduced but remain constant during the period of 96 hours after cooling. The level of postfire reduction of compressive strength of the analyzed concrete is substantial and could significantly affect the postfire load bearing capacity of a structure

Multiplicative Decomposition Based FDEM Model for Membrane Structures

A finite strain large displacement model for membrane structures based on the combined finite-discrete element method (FDEM) has been developed. The model is implemented in the open source FDEM package - Yfdem. The paper also presents benchmark tests and numerical results

Degradation of mechanical properties of high-strength concrete after exposure to fire

Prikazani su rezultati eksperimentalnog određivanja preostalih mehaničkih svojstava betona velike čvrstoće nakon požara. Ispitivano je: tlačna i vlačna čvrstoća te tangentni i sekantni modul elastičnosti. Ispitivanja su se provodila zagrijavanjem betonskih uzoraka na ciljanu visoku temperaturu. Osim mehaničkih svojstava betona prikazana su i preostala svojstva nakon hlađenja uzoraka. Rezultati su uspoređivani s vrijednostima navedenih svojstava danih u EN1992-1-2 i EN1994-1-2.The results obtained by experimental determination of residual mechanical properties of high-strength concrete after fire exposure are presented. The following properties are analyzed: compressive strength and tensile strength, and the tangent and secant moduli of elasticity. The testing is conducted by heating concrete samples to a high target temperature. In addition to mechanical properties of concrete, other properties registered after sample cooling are also presented. The results are compared with corresponding properties given in EN1992-1-2 and EN1994-1-2