Analiza ponašanja grupe elastičnih moždanika kod spregnutih nosača od čelika i betona

Abstract

Diskontinualni podužni smičući spoj ostvaren grupama moždanika jejednostavno i široko rasprostranjeno rešenje za sprezanje čeličnih nosača i montažniharmiranobetonskih ploča. Ovaj rad analizira mogućnost primene grupa moždanika saredukovanim rastojanjima između susednih moždanika u grupi. Osnovni cilj rada je dase istraži mogućnost smanjenja rastojanja između susednih moždanika u grupi u odnosuna minimalno propisana rastojanja. Smanjenje rastojanja između moždanika u grupi idimenzija grupe, omogućava izvođenje manjeg otvora u armiranobetonskoj montažnojploči potrebnog za smeštaj moždanika. Prikazano je sopstveno eksperimentalnoistraživanje nosivosti grupa moždanika, sprovedeno na Građevinskom fakultetuUniverziteta u Beogradu. Eksperimentalnim istraživanjem analizirana je mogućnostprimene grupe moždanika kod spregnutih greda u zgradarstvu. Ispitana je nosivost,deformabilnost i ponašanje, podužnog smičućeg spoja ostvarenog grupama moždanika.Glavni parametri analizirani u radu su: raspored moždanika u grupi, orijentacija grupemoždanika u odnosu na pravac podužne sile smicanja i međusobno rastojanjemoždanika. Istraživanjem je obuhvaćeno pet različitih dispozicija grupa od četirielastična moždanika sa glavom, kod kojih su međusobna rastojanja manja od minimalnopropisanih rastojanja u Evrokodu 4. Cilj istraživanja je i da se utvrdi kako smanjenjeminimalnih propisanih rastojanja između moždanika utiče na ponašanje, odnosnonosivost, duktilnost i ukupne deformacije podužnog smičućeg spoja. Korišćenimaterijali, polazne pretpostavke i postupak ispitivanja su u skladu sa Evrokodom 4.Metodom konačnih elemenata simulirano je eksperimentalno istraživanje a kalibrisannumerički model sa eksperimentom je poslužio za izvođenje zaključaka o ponašanjuveze ostvarene grupom moždanika sa glavom. Uočeni su i definisani modeli loma kojise mogu javiti u podužnim smičućim spojevima, formiranim grupama moždanika. Nauočenim modelima loma definisana su granična stanja nosivosti grupe moždanika.ivPomoću numeričkih modela urađena je i parametarska analiza koja je obuhvatilarazličite prečnike i grupe moždanika...

Discontinuous shear connection with groups of headed studs is simple andwidespread solution for connection between steel beam and precast concrete element.This thesis analyzes the possible applications of headed studs group with reduceddistances between adjacent headed studs in the group. The main objective of this studywas to investigate the possibility of reducing the spacing between adjacent headed studsin the group compared to the minimum required in Eurocode 4. Reducing the distancebetween the headed studs in the group and the dimensions of the group, would allowconstruction of a smaller hole in the reinforced concrete precast plate needed toaccommodate the headed studs. The paper presents the results of the experimentalresearch conducted on push-out tests at the Faculty of Civil Engineering at theUniversity of Belgrade. Throughout the experiment there has been analyzed thepossibility of using the headed studs group in composite beams for buildings. Thecapacity, deformability and behavior of shear connection with grouped headed studswas investigated (analyzed). A shape of group arrangement along with its orientation tothe applied load and distance between the studs were variables considered. The studyincludes five different groups of four headed studs, with the distance between headedstuds less than the minimum distances required in Eurocode 4. The aim of the researchis to determine how the reduce of the minimum required distance between the headedstuds affects to the behavior, shear capacity, ductility and total longitudinal sheardeformation of the shear connection. The materials, initial assumptions and test set upare in accordance with Eurocode 4. The FEM model is used to simulate the experiment.Calibrated FEM models with push-out tests were used to draw conclusions about thebehavior of shear connection with group of headed studs. The fracture models whichcan occur in longitudinal shear connection with headed studs group were identified anddefined in the paper. Ultimate limit state for headed stud group based on the fracturemodels is defined. Parametric analysis, which included a models with differentdiameters of headed studs and layout of groups were performed by numerical models.viBased on the results, the recommendations were derived for determining the shearcapacity of the headed studs group, when the distance between studs is less thanrequired by Code. The reduction coefficient was suggested to determine the shearcapacity of the headed studs group. Derived recommendations can be applied to shearconnections in composite steel-concrete beams applied in buildings...