Behaviour of built-up stainless steel members subjected to axial compression

[J.D. Dobrić]

PDF/A (230 listova)

Građevinarstvo-Čelične konstrukcije / Civil and Structural Engineering-Steel Structures

Iako je 2013. godine obeležena stogodišnjica pronalaska nerđajućeg čelika, njegova značajnija primena u građevinarstvu započinje tek početkom ovog veka. Austenitni nerđajući čelik odlikuje niz specifičnosti koje opravdavaju njegovu primenu u konstrukcijama posebne namene: postojanost i visoka otpornost na dejstvo korozije, značajan kapacitet plastifikacije i izražena duktilnost, poboljšanje svojstava materijala uticajem hladne deformacije, postojanost na visokim i niskim temperaturama, superiornost površinskog izgleda bez zaštitnih premaza, neškodljivost po okolinu. Najveći ograničavajući faktor za njegovu masovniju primenu je visoka jedinična cena, ali i nepotpunost tehničke regulative koja, još uvek, ne sagledava na odgovarajući način specifičnosti ovog materijala. Cilj istraživanja koje je prikazano u ovoj doktorskoj disertaciji je omogućavanje šire primene nerđajućeg čelika u konvencionalnim konstrukcijama kroz detaljnu analizu ponašanja centrično pritisnutih, hladnooblikovanih elemenata višedelnog preseka. Osnovni materijal primenjen u okviru istraživanja je nerđajući čelik austenitne mikrostrukture sa oznakom 1.4301. Predmet istraživanja su višedelni elementi formirani od dva C profila koji su međusobno direktno povezani šavovima ili zavrtnjevima. Eksperimentalnim ispitivanjem su obuhvaćene skoro sve osobenosti u ponašanju pritisnutih elemenata: ispitana su mehanička svojstva materijala, sagledan nivo asimetrije i anizotropije materijala, sagledan uticaj hladnog oblikovanja na poboljšanje mehaničkih svojstava materijala, utvrđen kapacitet nosivosti poprečnog preseka, izmerene početne geometrijske imperfekcije i određena nosivost elemenata na fleksiono izvijanje oko nematerijalne ose. Napredni numerički modeli na bazi metode konačnih elemenata su napravljeni da simuliraju ispitivanje pri fleksionom izvijanju a kalibrisani su na osnovu eksperimentalnih rezultata. Korištena je kvazi-statička analiza primenom eksplicitnog dinamičkog solvera softverskog paketa Abaqus. Ovako kalibrisani modeli na bazi MKE korišćeni su dalje za parametarsku analizu...

Although the centenary of the invention of stainless steel was celebrated in 2013, its more significant implementation in construction industry was not established until the beginning of this century. Austenitic stainless steel is characterized by a number of features which justify its use in construction for special purposes: durability and corrosion endurance, high plastification capacity and ductility, improved characteristics of materials when subjected to deformation, resistance to high and low temperatures, superior surface appearance without protective coating, environmental safety. The main limiting factor for its wider application is the high unit price, as well as the incompleteness of technical regulations which are not taking into account properly all the specifics of this material. The purpose of the research presented in this doctoral dissertation is to enable wider application of stainless steel in conventional structures through detailed analysis of the behaviour of cold-formed built-up compression members. The base material used in this research is austenitic stainless steel grade 1.4301. Object research are built-up members composed of two C sections in contact, connected by weld or bolts. Experimental works included all the major behaviour characteristics of the compression member: mechanical properties of the material were measured, the level of asymmetry and material anisotropy was assessed, as well as the effects of the process of cold forming on improvement of the mechanical properties of the materials. Initial geometric imperfections, ultimate resistance of cross-section, ultimate resistance members to the flexural buckling around intangible axis, were also considered in experimental works. Advanced numerical models based on the finite element method were built to simulate behaviour under flexural buckling and they were calibrated with respect to the experiment data. Quasi-static analysis with the explicit dynamic solver software package Abaqus was engaged for the buckling analysis...

austenitni nerđajući čelik, višedelan presek, samostalni elemenat, geometrijska imperfekcija, zaostali napon, nosivost preseka, nosivost elementa, fleksiono izvijanje

austenitic stainless steel, built-up member, chord (single member), geometric imperfection, residual stresses, resistance of the cross-section, resistance of a member, flexural buckling

624

Кonstruktivni elementi

Tekst