Investigating determination of ultimate strength and coefficient of behavior of lightweight concrete shear wall with LSF cold rolled steel frames using ANSYS software

Dissertation for Master's degree

Abstract:

Coping with external forces, including earthquakes, is one of the most important missions of civil engineers. To achieve this goal, the light metal frame system, which has advantages such as the possibility of industrial production, prefabability and lightness, can be considered as a suitable alternative to traditional systems. Shear wall panels consisting of cold rolled steel frame and cover bolted to it are one of the most common lateral bearing systems in these structures. Seismic performance of structures requires an analytical method which is a finite element method along with non-linear analysis, however, in line with this, appropriate shear walls should be used to restrain the forces. In this thesis, the shear wall panels of our frames were analyzed with the help of lightweight concrete (Lica and concrete foam) instead of steel sheets or sheet metal and by Ansys finite element software, which was evaluated on samples with a scale of 120 x 240 cm. Different thicknesses of shear walls were analyzed and their lateral performance was investigated by applying wheel loading on six walls. The main focus of this thesis is on the maximum lateral bearing capacity and the maximum ultimate resistance of the walls and the rational estimation of the coefficient of behavior (R) of the frames with shear wall bracing and also how they fail. For this purpose, six CFS frames with a sheet thickness of one millimeter were filled with concrete in the model software and the modeled frames were filled with concrete and leveled up to the edge of the frames with a thickness of one centimeter. Specimens were drawn under a specific lateral cyclic loading regime based on ASTM E2126-07 (38) method B for each applied curved wall. Then the parameters were calculated. Finally, the R factor was evaluated, and then the laboratory results were compared with the results of the software in the sampled state with concrete, as well as the software results of the walls with concrete with the software results of the walls with sheets.

Key words: shear wall panels, nonlinear analysis, cold-formed steel, light concrete, Lycafoam concrete

Chapter 1

General

Introduction

Mankind's urgent need to design and build buildings 1- Fast implementation 2- Resistant to lateral forces such as earthquakes 3- Light in structure and materials and executive materials 4- Ability to withstand high tension and safe behavior coefficient 5- The use of residential structures with multiple floors made us research this issue. In common buildings, despite the advanced design, the structure usually has poor performance in Iran, which means that the actual behavior of the structure during service is completely different from what was designed. Therefore, careful monitoring of the execution quality and compliance with the calculated details is absolutely necessary. Therefore, the prefabricated buildings in the factory will behave properly during service due to quality control and production according to the calculation plans. Meanwhile, LSF light steel frames with factory-made quality and simple, reliable, strong and fast connections are of particular importance. Also, the country's increasing need for more infrastructure in terms of housing, education, health facilities, treatment, welfare, industrial and commercial facilities, which is mainly caused by the increase in population and development, requires the use of new methods in building construction. In these methods, in addition to reducing the construction time, by saving on the consumption of traditional construction materials, the cost of construction is also reduced while maintaining the desired quality. In order to achieve the above goals, the rapid construction system was designed with comprehensive technical and economic studies in which the facilities and conditions in different parts of the country were considered, and it is introduced as a rapid construction system. (Hatami and Rahmani, 1389; Falah and Vatani Eskoi, 1382).

Shear walls are one of the main members and resistant to lateral loads, especially earthquakes, which are widely used in short and medium-rise metal buildings. Each panel of a shear wall can be made of a steel frame with a cold steel cross-section, where the poles and columns of the frame are connected by self-tapping screws or rivets. The use of composite frames with light concrete and cold-rolled light steel to increase the level of lateral shear resistance is very important in the reliability of the structure and increasing the number of floors.. The use of composite frames with light concrete and cold-rolled light steel to increase the lateral shear resistance can be very important in the reliability of the structure and increase the number of floors, which we will discuss in this thesis (AISI.) [1]. 1-1 History 1-1-1 History and reasons for using LSF systems CFS started in 1850 in England and America by using it in the manufacture of car accessories, but it was not used in building construction until the First World War. From 1930 onwards, LSF steel parts were used in commercial and industrial buildings, but due to the cheapness of wood, it could not compete economically with it as a common housing system. Since 1990, the increase in the price of wood and the emergence of environmental problems in the construction industry caused the LSF construction system, which is built using galvanized CFS steel parts, to be used for the construction of residential units. This construction system has been able to receive multi-storey construction certificates in different countries and has carried out extensive activities in this field, especially in Parand and Tirana, in Iran (Vathoqi Far and Adel Peror, 1386; Hatami et al., 1388).

The use of LSF construction system for housing construction started in Australia after World War II. If before that, housing construction was mainly done using wooden frame. Following the construction developments in America, there were also developments in this country, the main of which was the application of this system in Australia. This system was able to grow significantly in the construction industry of Australia due to its high speed and resistance. And now the best roll form machines in the world are in the monopoly of that country. In Sweden, wood was the most common building material, but due to the decrease in the average life of trees since the 1990s, the builders tried to replace the LSF system in that country. Currently, in the Netherlands, the LSF system plays a major role in the construction of residential structures and schools. In 1989, the Netherlands Building Research Foundation SBR investigated the potential of using the LSF system for house construction, and the results of the investigation revealed that the use of this construction system leads to easier design and environmental benefits, but it is a little more expensive than wooden structures. In France, in recent years, the style of this system has been limited in place of steel and concrete systems. In Korea, brick and concrete were the main construction materials until 1996, and in-situ concrete systems were used in high-rise buildings until February 1996, POSCO started the LSF system for the first time in the city of Phuong by building 700 two- to five-story villas.

In 1995, Davies et al. investigated the use of thin-walled steel in short and medium-sized modular buildings. In 1996, Surte et al. investigated the dynamic performance of shear walls in light steel frames. In the same year, Davies et al. have investigated the shear behavior of compression joints in light steel frame structures. In 1997, Driver et al. investigated the seismic behavior in steel shear walls. In 1998, Pi and Kinney have investigated the shear strength in steel compression joints. In the same year, Lennon et al compared a number of mechanical connections in cold rolled steel. In the same year, Algali et al analyzed the behavior of thin steel shear walls. In 1999, Lawson investigated modular construction using a light steel frame. In 2000, Lubel et al. investigated the performance of unstiffened shear walls under intermittent loading. In 2004, Dubina investigated the performance of shear panels of cold-rolled master walls under uniform and intermittent loading. In the same year, Tian et al. investigated the breaking strength and hardness of cold-rolled steel wall frames. In 2005, Pasteur and Rodrigues modeled the residual shear walls with cross-shaped braces in thin walls of structures. In the same year, Elkharat and Rogers developed a light steel frame laboratory model reinforced by bracing walls. In 2006, Volkovich and Johanson have investigated the traditional design model in walls with single-layer and double-layer expanding gypsum panels that are resistant to fire. In the same year, Gore Gluski has presented a simple method for calculating the U-Valvoder index of light frames