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INVERSE MODEL FOR PULLOUT DETERMINATION OF STEEL FIBERS


Kožar, Ivica; Torić Malić, Neira; Rukavina, Tea
INVERSE MODEL FOR PULLOUT DETERMINATION OF STEEL FIBERS // Connections between Steel and Concrete, Proceedings / Sharma, Akanshu ; Hofmann, Jan (ur.).
Stuttgart: University of Stuttgart, 2017. str. 1248-1257


Naslov
INVERSE MODEL FOR PULLOUT DETERMINATION OF STEEL FIBERS

Autori
Kožar, Ivica ; Torić Malić, Neira ; Rukavina, Tea

Vrsta, podvrsta i kategorija rada
Poglavlja u knjigama, znanstveni

Knjiga
Connections between Steel and Concrete, Proceedings

Urednik/ci
Sharma, Akanshu ; Hofmann, Jan

Izdavač
University of Stuttgart

Grad
Stuttgart

Godina
2017

Raspon stranica
1248-1257

ISBN
978-3-945773-06-2

Ključne riječi
Fiber reinforced concrete ; samples ; measurements ; stochastic inverse model ; Levenberg – Marquardt procedure

Sažetak
Fiber reinforced concrete (FRC) is a material with increasing application in civil engineering. Here it is assumed that material consists of a great number of rather small fibers embedded the concrete matrix. It would be advantageous to predict mechanical properties of FRC using nondestructive testing ; unfortunately, many testing methods for concrete are not applicable to FRC. In addition, design methods for FRC are either inaccurate or complicated. In three-point bending tests of FRC prisms, it has been observed that fiber reinforcement does not break but simply pulls out during specimen failure. Following that observation, this work is based on an assumption that the main components of a simple and rather accurate FRC model are mechanical properties of the concrete matrix and fiber pullout force. Properties of a concrete matrix could be determined from measurements on samples taken during concrete production and fiber pullout force could be measured on samples with individual fibers embedded into concrete. However, there is no clear relationship between measurements on individual samples of concrete matrix with a single fiber and properties of the produced FRC. This work presents an inverse model for FRC that establishes a relation between parameters measured on individual material samples and properties of a structure made of the composite material. However, deterministic relationship is clearly not possible since only a single beam specimen of 60 cm could easily contain over 100000 fibers. Our inverse model assumes that probability density function of individual fiber properties is known and that global sample load – displacement curve is obtained from the experiment. Thus, each fiber is stochastically characterized and accordingly parameterized. A relationship between fiber parameters and global load – displacement response, the so-called forward model, is established. From the forward model, based on Levenberg – Marquardt procedure, the inverse model is formulated and successfully applied.

Izvorni jezik
Engleski

Znanstvena područja
Građevinarstvo



POVEZANOST RADA


Projekt / tema
HRZZ-IP-2013-11-9068 - Višeskalni model betona s identifikacijom parametara (Ivica Kožar, )

Ustanove
Građevinski fakultet, Rijeka