ارزيابي آزمايشگاهي يك نوع اتصال صلب پيشنهادي تير به ستون پيش‌ساخته‌ي بتني با المان رابط فولادي تحت اثر بارهاي رفت و برگشتي

Experimental Study on a Proposed Rigid Precast Connection of Beam to Column using a Steel Linkage Element under Cyclic Loading

در اين نوشتار، يك نوع اتصال صلب به منظور استفاده در سازه ‌هاي پيش‌ساخته ي بتني پيشنهاد شده است. در اين اتصال از يك المان فولادي رابط براي متصل‌كردن تير و ستون پيش‌ساخته استفاده شده است. اين المان، به دو صورت نمونه‌ي پيچي و جوشي پيشنهاد شده است. نمونه‌هاي مذكور در مقياس واقعي تحت آزمايش بارگذاري سيكليك قرار گرفته و نتايج آنها از لحاظ ميزان مقاومت، سختي، ظرفيت جذب انرژي، و شكل‌پذيري و همچنين نحوه‌ي پيدايش و گسترش ترك با نتايج حاصل ازآزمايش نمونه‌ي يكپارچه‌ي معمولي مقايسه شده است. نمونه‌ها تمامي ضوابط آيين‌نامه‌ي 01-1/1 ACI T را برآورده كرده‌اند و لذا قابليت به‌كارگيري در سيستم قاب خمشي پيش‌ساخته‌ي بتني را دارند. همچنين نوع و توزيع ترك‌ها و مكانيسم شكست نمونه‌ها دال بر رفتار شكل‌پذير آنهاست.

One way to construct reinforced concrete structures is by the use of precast technology. Precast structures have different advantages, such as high quality control, economical cost, speed implementation and appropriate seismic behavior. The quality of connection of precast elements to each other is one of the most important parameters in the behavior of a precast structure. Due to the absence of an appropriate precast rigid connection, precast concrete structures are mainly used as a simple frame with a simple connection of beam to column and cast-in-place shear wall. In this study, a reliable system for precast structures to connect beam to column is created and undertaken with steel linkage elements. The connection of steel linkage to a column is performed with bolts, and the beam to this steel linkage is performed with bolts or welding. This method enables creation of concrete structures with higher quality than cast-in-place structures through minimizing in-situ concreting, as well as maximizing the speed of construction and usage of ductile and exchangeable elements in sensible locations. During the last decades, a significant body of research has been conducted on connections in precast structures. The main variables in these studies are the executive details, as well as the location of beam-column connections. This paper presents the test results of a new rigid connection for precast concrete frames. In this connection, precast concrete beams and columns are connected to each other using a steel linkage element. Two types of bolted and welded connections are compared to monolithic specimens in terms of stiffness, strength, energy dissipation capacity and ductility factor. All specimens satisfied all three criteria of ACI T1.1-01, including; for no cycle, the relative energy dissipation ratio was not less than 12.5%, the secant stiffness from a drift ratio of -3.5% to a drift ratio of +3.5% was not less than 0.05 times the stiffness for the initial drift, and, finally, the ultimate strength recorded for the specimen was not lower than 75% maximum strength.