# Study on Shear Performance of Short Bol Interface in ECC-Steel Bridge Deck Composite Structure
## 1 Introduction  
The orthotropic steel bridge deck has become one of the forms used in large- and medium-span steel bridges around the world due to its advantages of being lightweight, its large spanning capacity and its comfortable driving performance [1; 2; 3]. The orthotropic steel bridge deck pavement is very different from general pavement. The wheel load stress on the steel bridge deck pavement's structure is more concentrated; moreover, it is different from the fixed mode of the pavement superstructure under compression and the lower structure under tension. Due to the influence of transverse ribs, longitudinal ribs, etc., under the action of vehicle loads, load effects such as negative bending moment, interface shear stress and interface slip will appear at the corresponding position of the upper part of the bridge deck pavement structure [4; 5; 6]. Therefore, the ability of a cement-based bridge deck to resist bending deformation or bending tensile stress is extremely important. Engineered Cemertitious Composites (ECC) are a new type of polyvinyl alcohol, fiber-reinforced, cementitious composite with high ductility, high toughness and good crack control performance [7; 8; 9; 10]. It was originally proposed by Professor [PERSON] of the University of Michigan in 1992 [11]. About 50% of the cement can be replaced by mining wastes such as coal gauge powder and silica fume, which strengthens the key mechanical performance indicators for concrete materials and is conducive to energy saving and ecological environment protection [11; 12]. In addition, ECC materials havegood ductility and self-healing ability. Under an external load, the structure is always in the elastic stage within the stress bearing-range of ECC and can gradually recover to its original state after the external load is removed, while the ECC concrete layer directly bears the vehicle load and plays the role of dispersing it and preventing seepage. It is therefore beneficial to solve the problems of the steel bridge panel pavement structure cracking and the corrosion of steel bridge panel [13; 14]. The steel-concrete composite structure makes full use of the tensile properties of steel and the compressive properties of concrete, has excellent mechanical properties and has been widely used in bridge construction [15; 16; 17]. Because of its super ductility and good deformation performance, ECC is applied to steel bridge decks to form a steel-ECC composite structure. Under the condition of equal absolute stress values, the fatigue life of ECC far exceeds that of ordinary concrete, which can effectively improve the fatigue resistance of orthotropic steel bridge decks [18; 19; 20; 21]. Studs are used as shear connectors to connect the steel bridge deck and ECC bridge deck pavement as a whole to ensure that the steel and concrete work together, and it is necessary to study it. Engineering examples show that the application of ECC to the pavement of steel bridge decks will achieve a fatigue life of ordinary concrete with a thinner thickness [22]. In order to match the thinner pavement, short studs are needed as shear members to participate in the interface shear resistance. In the 1950s, [PERSON] and [PERSON] systematically studied the shear performance of stud connectors by using push-out experiments and proposed an empirical formula for the critical bearing capacity of studs [23; 24]. The length-to-diameter ratio is above four. In 2004, the Mihara Ohashi Bridge in Hokkaido, Japan, successfully applied 40 mm-thick ECC to replace half of the pavement layer [25]. Since the ECC layer is thin and has superior performance, studs with a length-to-diameter ratio of less than four are used as shear elements. The team of [PERSON] studied the shear performance of short studs in ultra-high-performance concrete (UHPC) and proposed a practical empirical formula, as well as a formula for calculating the shear capacity of the medium and short stud load-slip full curves of UHPC [26].