Thesis Defense - Burak Talha Kılıç (MSCE)

Burak Talha Kılıç - M.Sc. Civil Engineering

Asst.Prof. Bülent Erkmen - Advisor

DETERMINATION OF EFFECTIVE BREADTH WIDTH OF STIFFENED

PLATE STRUCTURES BASED ON NONLINEAR FINITE ELEMENT ANALYSIS

Date: 21.08.2019

Time: 13:00

Location: AB1 511

Thesis Committee: 

Asst. Prof. Bülent Erkemen,  Özyeğin University

Asst. Prof. Yiğit Özçelik,  Özyeğin University

Asst.Prof. Onur Şeker, MEF University

Abstract

An economical and effective design of plates loaded by out-of-plane loads such as pressure or blast can be obtained by using stiffeners instead of increasing plate thickness. Therefore, stiffened steel plates are widely used in many different industries for different purposes and structures such as aerospace engineering for the resistance of wind pressure and marine structures for ship skeleton. Similarly, such steel wall systems are also widely used in petrochemical industry especially in offshore and onshore platforms as blast walls and blast-resistant steel structures as control rooms, office buildings, and living quarters in areas with a high risk of explosion, fire, or danger from toxic materials in the petrochemical industry.

For such steel wall structures ultimate strength capacity, wall stiffness, and the requirement for weld connection between the wall plate and stiffeners depend on effective breadth of the plate, which is the part or breadth of plate working with each stiffener as its flange. This breadth width is typically predicted based on plate nonlinear stress distribution occurring due to out-of-plane loading such as pressure, blast, wind etc. Although there are a number of studies for such cold formed plate systems, they are mainly focused on effective width concept, which is based on in-plane loading only.

In the first part of this study, nonlinear finite element models of stiffened plate structures subjected to uniform out-of-plane pressure loading were generated by using a general-purpose finite element program Abaqus CAE. The effective breadth of these wall systems was calculated using nonlinear stress distribution through plate thickness and along plate width to determine axial load carried by plate. The effective breadth width was calculated as the plate width needed to carry the same axial load but with uniform stress, which is equal to the maximum computed stress from the model, along the plate width. A parametric study was also conducted to determine the effects of walls design parameters such as spacing of stiffeners, plate thickness, type of stiffener as well as its aspect ratio on breadth width.

In the second part, effective breadth of the walls was investigated by using simple beam method. In this method, such structures were modeled as a simple beam because modeling and analyzing of these walls require a lot of computational time, high-performance computer, costly finite element software package as well as expert engineering judgment. For this purpose, prototype walls were created based on different yielding criteria of plates. At the same time, the prototype walls that have the same geometric and material properties were modeled as simple beams. The correlation between walls and simple beams were discussed by using support reaction per stiffener versus vertical displacement curve. This part investigates how close the behavior of different featuring walls can be modeled by simple beam method.

Bio

Burak Talha Kılıç was born in Üsküdar, İstanbul on May 19, 1994. He graduated from Rezan Has High School in 2012. He entered Özyeğin University in September 2012 and received BSc degree of Civil Engineering as a top-scoring student in June 2017. In September 2017, he entered Graduate School of Engineering at Özyeğin University in İstanbul. He mainly studied structural engineering especially stiffened plate structures and wrote his thesis under the supervision of Dr. Bülent Erkmen. During one and a half year at Özyeğin University, he worked as a teaching assistant. Currently, he has been working as a research assistant in Kırşehir Ahi Evran University.