Constructional System of Cold Formed Light Steel Framing (LSF)

Cumhuriyet Üniversitesi Fen Fakültesi Cumhuriyet University Faculty of Science Fen Bilimleri Dergisi (CFD), Cilt:36, No: 3 Özel Sayı (2015) Science Journal (CSJ), Vol. 36, No: 3 Special Issue (2015) ISSN: 1300-1949 ISSN: 1300-1949 Constructional System of Cold Formed Light Steel Framing (LSF) Hadi AZIZIAN Young Researchers and Elite Club, Mahabad Branch, Islamic Azad University, Mahabad, Iran Received: 01.02.2015; Accepted: 05.05.2015 ______________________________________________________________________________________________ Abstract. Nowadays, various methods are used to strengthen structures against earthquake. One of the new methods which can be used in improving seismic behavior of structures is to use light steel framing. Lightweight steel framing system (LSF) is a structural system which is employed to implement buildings which are mostly low and medium rise buildings (at most 5 stories). This system which is very similar to wooden structures’ construction methods is constructed based on applying some constituents called Stud or Track. The main structure of the building is established from combining cold formed galvanized profiles. The purpose of the present study is to define, explain and apply lightweight steel framing as well as referring to required machineries and physical properties of the needed steel. In this regard, the requirements of design, execution, shell life, various stages of designing, foundation of building, internal and external coverings of ceiling and wall, electric installations, doors and windows are also discussed. Finally, advantages and disadvantages of lightweight steel framing systems are stated. The present project can be introduced as the most comprehensive and complete instruction for lightweight steel framing structural systems. Keywords: new steel structure system, lightweight steel framing, light steel framing (LSF) design and execution __________________________________________________________________ 1. INTRODUCTION Using the members of cold formed steel began from the 1850s but it was not widely used until the first dissipation of American association of iron in 1946. Today, due to appropriate quality of construction, high speed, and high resistance against earthquake, it is used in England, America, Australia, Canada, Japan, etc. these buildings consist of three main constituents including sections consisted of cold formed sheets for structure, plasterboard as internal covering, and acoustic and thermal insulation. These buildings as an independent structural system are mostly applied in mass construction of two-story buildings, small commercial buildings, industrial units, and one-story sport salons. It seems that this structural system of gravity load is also able to be combined with other structural systems such as structural reinforced concrete walls and can be applied to construct low rise buildings as mixed structural system. To construct cold formed sections, it is legal to use various shapes according to regulations related to these structures. The vertical components of this system act as column load bearing in gravity loads. Some of these members placed in the span of the structure’s lateral restraining. In addition to gravity load, this system undergoes forces derived from lateral loads and these members are introduced as stud in the system. The ceiling of this building’s structure consists of cold formed beam such that the distance of beams is determined with respect to load bearing capacity of the member and the dimensions of the ceiling covering parts which can be wooden or cement boards or reinforced concrete slab. Cold formed profiles have low resistance against fire and should be well protected. One of the causes of applying gypsumas internal covering of the system is to achieve this purpose. Thin wall steel sections are galvanized steel sheets which are shaped using cold rolling and roll forming in factory. Based on the regulation formulated for cold formed steel sections, the thickness of the base steel (the thickness of the steel without computing protective coverings) has been formulated between 0.455 mm to 3 mm. Producing and cutting this section in factory _____________ *Corresponding author. Email address: Special Issue: The Second National Conference on Applied Research in Science and Technology http://dergi.cumhuriyet.edu.tr/cumuscij ©2015 Faculty of Science, Cumhuriyet University AZIZIAN causes that producing sections is performed with appropriate and uniform quality in very high volume and speed. Close distance of these steel sections to each other creates load bearing walls which have appropriate resistance and rigidity against lateral loads due to wind and earthquake. Cold formed lightweight steel buildings are implemented through two general methods of stratified framing and continuous framing. In stratified framing method, the wall of the story is firstly implemented. Then, the ceiling, completing wall and ceiling framing, the wall of the upper story are implemented, respectively. In wall execution method, the walls are built and installed in several stories and then, the ceiling of the stories is implemented. 1.1. Applying Construction System of Lightweight Steel Framing (LSF) Construction system of lightweight steel framing (LSF) is used in various types of constructions such as villas, residential buildings, administrative buildings (up to two-story), hotels, hotel apartments, schools and universities, restaurants, residential and recreational camps, etc. For example, it can be referred to multi-unit buildings, small commercial offices and buildings, sport and educational buildings, industrial units, half-story construction within high height constructions, developing the number of stories on roof of existing buildings, pre-casted applied spaces such as WC in the form of Box System, reconstructing regions damaged due to natural disasters (earthquake, flood, tornado, etc.) in terms of permanent settling, temporary settling of victims of natural disasters (given to low speed and cost of construction), and constructing small and inexpensive housing. On the other hand, constructing new residential towns (in the frame of mass building) by considering cultural, economic and geographical points in design as well as designing towns based on the last scientific achievements given to predicting urban needs by considering development design, and new construction in small towns and villages (such as residential, educational, cultural, etc.) are of the applications of LSF’s construction system. In the following figure, a schematic of a building with LSF’s construction system has been presented. Figure 1. The schematic of a building with LSF’s construction system 1.2. Construction Machineries and Characteristics of Allowed Steels To construct buildings of LSF systems, simple machineries such as rail, pin firing guns, elevators, cut saws for steel and plasterboards are employed. Furth (...truncated)