# An Investigation on Base Metal Block Shear Strength of Ferritic Stainless Steel Welded Connection
## 1 Introduction  
As a structural material of buildings or infrastructure, stainless steel has important characteristics such as corrosion resistance, durability, fire resistance, and aesthetics compared to carbon steel. Therefore, the use of stainless steel as nonstructural members of interior and exterior materials, as well as structural members of buildings at home and abroad, has been increasing recently. Structural design specifications for cold-formed stainless steel were established in the United States (American Society of Civil Engineers, ASCE) [1], Europe (Eurocode 3, EC 3 part 1-4) [2], Japan (Stainless Steel Building Association of Japan, SSBA) [3], and Australia/New Zealand (AS/NZS 4673) [4]. However, in Korea, stainless steel has not been designated as a structural steel material in the Korean Building Code (KBC) up to now [5]. Moreover, the structural design standards for stainless steel structural members are not yet available. In Korea, recently, many researchers have performed studies on structural behaviors, such as fracture mode and ultimate strength of bolted and welded connections of thin-walled (cold-formed) stainless steel plates through experimental and analytical methods [6; 7; 8; 9]. Since ferritic stainless steel among various types of stainless steels does not contain smaller amounts of alloying elements such as molybdenum, nickel, titanium, and niobium, the material cost is lower than austenitic and duplex stainless steels, and its demand for use as interior and exterior materials and structural materials of general buildings, which are not harshly corrosive environmentssuch as coastal areas and chemical plants, is increasing [10]. Additionally, it usually possesses better deep drawability and resistance to stress corrosion cracking. However, ferritic stainless steel has lower ductility than austenitic stainless steel and contains a large amount of carbon (C), which causes embrittlement (brittle fracture) of the heat affected zone (HAZ) and poor weldability than austenitic stainless steel. Ferritic stainless steels are hardened by cold working and not hardened (strengthened) by quenching, and develop minimum hardness and maximum ductility, impact toughness, and corrosion resistance in the annealed and quenched condition [11]. With the development of welding technology for ferritic stainless steel, recently, all of the ferritic types are considered weldable with the majority of the welding processes except for the free machining grade (AISI **430F**, which contains high sulphur content). ASCE specifies that Type 430 stainless steel shall not be used for welded connections due to deterioration of corrosion resistance and toughness. Thus far, there have been few studies on the structural behaviors of ferritic stainless steel welded connections. As a series of the block shear strength estimation for stainless steel welded connection, experimental and analytical studies have been performed on the structural behavior of the base metal and weld metal fracture of welded connections made of austenitic stainless steel STS304 (ASTM 304 type) [12] and STS304L (ASTM 304L type) [13]. The predicted block shear strength according to the current design equations of KBC, AISC, and EC3. Moreover, the proposed equations of previous studies on carbon steel welded connections by [PERSON] [14] and [PERSON] [15] were compared with the experimental and analytical results. However, these research projects did not include the consideration of welded connections with ferritic stainless steel, which has different material properties such as yield stress, tensile strength, yield ratio, elongation, etc. [16]. [PERSON] and [PERSON] have studied block shear behavior of bolted connections and proposed the block shear equation considering a limiting shear tearout stress of 0.6 \(Fu\) on each effective shear area and shear failure plane to be midway between the gross and the net shear planes [17].