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ON THE EFFECTS OF CIRCULAR BOLT PATTERNS ON THE ...

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CHAPTER 5<br />

5. DEVELOPMENT <strong>OF</strong> HYSTERESIS MA<strong>THE</strong>MATICAL MODELS<br />

5.1 Introduction<br />

The details of the finite element models used for validation of the numerical models were presented in<br />

the previous chapter. In this chapter, the test matrix used and the results of finite element analysis<br />

obtained from this parametric study are discussed. To simulate the tri-linear moment-rotation hysteresis<br />

behavior of the connection observed during testing, four parameters are required. These parameters are<br />

selected as the moment capacity of the connection at yield (My), the initial stiffness of the connection (E),<br />

the post yielding stiffness of the connection (Et), and the maximum rotation of the end-plate at the fracture<br />

of the bolt (θf). These parameters can be used to calculate the value of the moment capacity of the<br />

connection at fracture (Mf), and the rotation of the end-plate at yield (θy). These parameters for the<br />

models with circular and square bolt pattern are presented and compared in this chapter. Finally, non-<br />

linear regression was used to develop questions for parameters defining connections hysteresis moment-<br />

rotation behavior.<br />

5.2 Selection Of Test Cases<br />

The focus of this study is to understand the behavior of the extended end-plate connections with<br />

circular bolt pattern and compare their behavior with the behavior of the connections with traditional<br />

square bolt pattern. To achieve this goal, parametric studies were conducted on one hundred and eighty<br />

two models with circular and square bolt pattern configurations and the results were compared. The<br />

values of the bolt-diameter, end-plate thickness, and beam sizes were varied in order to investigate the<br />

effect of each component on the connection performance. The values of bolt-diameter, bd, used were<br />

1 2<br />

, 5 8<br />

, 3 4<br />

, 1, 11 8<br />

and 1 1 4<br />

in (127, 159, 190, 254, 285, and 317 mm), while the thickness values<br />

of the end-plate, tp, were 1 2<br />

, 5 8<br />

, 3 4<br />

, 1, 11 8<br />

,1 1 4<br />

, and 1 1 <br />

2<br />

in (127, 159, 190, 100, 285, 317,<br />

and 381 mm). The test matrix was modified several time throughout the research to eliminate the<br />

66

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