مطالعه تجربی و عددی بر رفتار مکانیکی اتصالات فولادی با مقاومت بالا
Abstract
1- Introduction
2- Experimental program
3- Finite element analysis
4- Experimental and finite element analysis results
5- Parametric analysis
6- Theoretical analysis of EC3
7- Conclusions
References
Abstract
Based on static tensile test of 20 Q460D high-strength steel bolted connection joints, influences of high-strength steel material strength and bolt arrangement pattern on bearing capacity and deformation of connections were analyzed. According to differences of end distance, edge distance, and pitch between bolts, finite element modeling, theoretical calculation, and test results were compared, a quantitative analysis was carried out for mechanical property of high-strength steel bolted connections, and applicability of relevant standards was investigated. The study showed that bearing capacity and deformation of specimens for Q460D high-strength steel increased as pitch increased when bolts were under transversal arrangement. Influence of increased edge and end distance on bearing capacity of the connection was minimal after standard value of the structure was reached. Stress nephogram obtained from numerical analysis and plastic region presented symmetrical distribution with two holes bearing balanced stress, fitted curve points were dispersedly distributed, and margin of theoretically calculated value was large when EC3 standard was used. When bolts were under longitudinal arrangement, bearing capacity of the specimens only presented a linearly increasing trend as pitch increased, two holes bore unbalanced stress in stress distribution, stress borne by bolt hole at end part and its deformation were both large, and bearing capacities of end and middle bolts calculated according to the EC3 standard were relatively accurate. This study can provide a theoretical basis for design and connection structure of Q460D high-strength steel bolted connection joints.
Introduction
With the improvement of steel production technology and maturation of corresponding welding materials and connection technology, novel high-strength steel materials have been successfully applied in many buildings globally and favorable social and economic benefits have been achieved [1–4]. Since the late 1960s, partial scholars have carried out a few experimental studies on high-strength steel bolted connections, mainly analyzed influences of bolt pitch and high-strength steel material properties on bearing capacity of connection joints, and discussed the applicability of existing design methods to high-strength steel bolted connection. Wallaert and Fisher [5,6] studied influences, such as bolt pretension, shearing plane position, contact surface roughness, bolt grade, and diameter on shear resistance. Zeynali et al. [7] analyzed influences of different material properties, number of bolts, amount of frictional coefficient and the type of connections on load-bearing properties of bolted connection. Pavlina [8] estimated yield and tensile strength of steel materials according to steel hardness measurement. Dusicka et al. [9] studied influences of different plate thicknesses and hole diameters on bearing capacity of bolted connection. Moze and Beg [10–12] conducted a test on high-strength steel bolted connections and proposed a correction formula. They also believed that the EC3 standard was very conservative; that is, a high steel grade leads to significant strength loss. Sterling [13] carried out static tensile test of eight groups of bolted butt connection and analyzed influences of bolt pitch and length of bolted connection on bearing capacity and deformation performance of the connection. Shi et al. [14] tested shear resistance of high-strength bolted-pressure-bearing connection joint and analyzed influences of plate thickness, end distance, and tensile strength. They also discussed load-bearing features of short- and long-joint connections. Kim and Kuwamura [15,16] analyzed influences of plate thickness, edge and end distance etc. parametric on the bearing deformation capacity and failure modes by finite element. Puthli and Fleischer [17] analyzed influences of bolt pitch,edge and end distance on load-bearing properties of bolted connection and proposed suggestions for parameter values.