An Applicability of Proposed FE Analysis Method and Power Model

Initially, to assess an applicability of the proposed FE analysis method for simulating moment – rotation behavior of top – and seat-angle connections, numerical analyses for three connection models were performed and those numerical results together with those obtained using Kishi-Chen’s three – parameter power model (1990) were compared with the experimental ones. The results of the first

FE analysis ———— Power model о Experiment

Fig. 5. Comparison of M — 0r curves among FE analysis, power model and experiment.

two experiments (A1 and A2) reported by Azizinamini et al. (1985) and the other Test 3 reported by Harper (1990) were used for the comparisons. Following those experiments, a prescribed pretension force (40% of ultimate strength of bolt) was considered for all bolts of the connection. The com­parisons of M — 0r curves among analytical and experimental results are shown in Figure 5. It is observed that the curves obtained from FE analysis and power model prediction equation are almost similar to the experimental ones in the linear elastic and early plastic ranges. However, maximum moments from FE analysis for connection models A1 and A2, and from power model for all the three cases are smaller than those from test data. The differences among those three results in the plastic region may be caused by the following reasons:

(1) In the power model, angles are treated as perfectly elasto-plastic material and bolts are assumed to be perfectly rigid body, and the locations where plastic-hinges are formed in angles are logically fixed;

(2) There are some differences between the material properties used in FE analysis and those of test specimens.

(3) There may be experimental errors.

Even though analytical results differ a little from experimental ones, it is supposed that the proposed FE analysis method can be applied to more precisely investigate nonlinear connection behavior of top – and seat-angle connections considering pretension force introduced in bolts. In addition, it is also reasonable to conclude that the power model has a potential to predict M — 9r curves of top – and seat-angle connections satisfactorily.