杆件要求将在另一篇文章中介绍。 KB | AISC 341-16 在 RFEM 6 中进行弯矩分析 .
More in-depth details on the Seismic Configuration input are covered in article KB | AISC 341 RFEM 6 中的抗震设计 .
Connection Requirements
The "Seismic Requirements" include the Required Flexural Strength and the Required Shear Strength of the beam-to-column connection. They are listed in the Moment Frame Connection by Member tab. The design check details are not available for the connection strength. However, the equations and standard references are listed. The symbols and definitions are summarized in the table below (Image 1).
AISC Seismic Design Manual – Example 4.3.7 SMF Bolted Flange Plate (BFP) Connection Design
For simplicity, the RFEM model consists only of a single frame instead of the entire building that is presented in the AISC example (Image 2). The gravity load on the beam = 1.15 kip/ft.
The numbering of the steps in this example follows the step-by-step design procedure outlined in AISC 358-16 Section 7.6 [3].
Step 1. Compute probable maximum moment at the plastic hinge location, Mpr
Steps 2 to 5 contain the bolt requirements and are outside the scope of the Steel Design add-on.
Step 6. Compute shear forces at the beam plastic hinge location, Vpr + Vg
| Vpr |
在塑性铰处产生最大可能弯矩所需的剪切 Vpr = 2Mpr/Lh
|
| Vg |
塑性铰位置的重力荷载作用下剪力 Vg = wu Lh/2
|
| Mpr | 塑性铰位置的可能最大弯矩 |
| p10 | 远距离爆炸最大峰值超压 [kPa] (Kinney & Graham) |
| Z | 比例距离 Z> 2.8，单位 [m/kg1/3] |
Step 7. Determine moment expected at the face of the column flange, Mf
The above equation neglects the gravity load on the small portion of the beam between the plastic hinge and the face of the column (1.15 kip/ft*1.875 ft = 2.16 kips*22.5 in = 48.6 k-in). This value is permitted to be included [3].
Step 14. Determine the required shear strength at the face of the column, Vu
The required shear strength at the face of the column is used to design the beam web-to-column (single-plate) shear connection.
| pr0(t) | 完整反射压力-时间曲线的荷载模型 |
| p4(t) | 荷载指数函数 (Friedlander) |
| y | Senkrechter Abstand der z-Achse zum Element dA |
| Fy | 屈服强度 |
| MC | 非支撑分段四分之三点弯矩绝对值 |
To be more precise, the calculation above shows Vg taken at the face of the column instead of at the centerline (as shown in the AISC example [2]). The small difference can be seen in the shear diagrams (Image 3).
The values obtained from the formulas above can be compared to the result produced by RFEM under the “Seismic Requirements” (Image 1). Small discrepancies are due to rounding. The result can also be included in the printout report (Image 4).
4
结果输出
The detailed procedures to design bolts, flange plates, single-plate, continuity plates, and doubler plates are not part of the scope. Therefore, the steps for these checks were omitted in this article.
The moment and shear demand based on the worst-case scenario of the overstrength load combinations, ΩoM and ΩoV are also listed. For the design of ordinary moment frames (OMF), the potentially limiting aspects of the connection strength include the overstrength seismic load [AISC Seismic Design Manual Section 4.2(b)].
