A moment-end plate connection, also known as a moment connection or moment-resisting connection, is a type of structural connection used to transfer bending moments between members. It is commonly used in steel structures where the connection must resist significant bending moments. The design criteria for a moment-end plate connection involve determining the required end plate dimensions, bolt sizes and spacing, and verifying the adequacy of the connection to safely transfer the applied moments. Here is a step-by-step procedure for designing a moment-end plate connection:
Step 1: Identify the Member Configuration Determine the specific configuration of the members involved in the connection, including the beam and the column. Gather information about their dimensions, material properties, and the connection requirements.
Step 2: Determine Applied Moments Identify the moments that will be applied to the connection, such as the maximum positive and negative moments. Determine the magnitude, direction, and distribution of these moments.
Step 3: Analyze the Structure Perform a structural analysis of the entire structure to determine the forces and moments acting on the connection. Consider the loading conditions, support conditions, and member stiffness.
Step 4: Determine Required End-Plate Dimensions Calculate the required dimensions of the end plate based on the applied moments, the desired connection capacity, and design code requirements. The end plate dimensions should be selected to provide sufficient bearing area and stability for the connection.
Step 5: Check End-Plate Shear Strength Check the shear strength of the end plate to ensure it can safely resist the applied shear forces. Verify that the shear stress is within the allowable limits specified by design codes or standards.
Step 6: Check End-Plate Moment Capacity Check the moment capacity of the end plate to ensure it can safely resist the applied bending moments. Verify that the moment stress is within the allowable limits specified by design codes or standards.
Step 7: Determine Bolt Size and Spacing Determine the required bolt size and spacing based on the applied moments and the desired connection capacity. Calculate the number of bolts needed to safely transfer the moments. Consider factors such as bolt shear strength, bearing strength, and spacing requirements.
Step 8: Check Bolt Shear Strength Check the shear strength of the bolts to ensure they can safely resist the applied shear forces. Verify that the shear stress is within the allowable limits specified by design codes or standards.
Step 9: Check Bolt Bearing Strength Check the bearing strength between the bolt and the end plate to ensure it can safely transfer the applied forces. Verify that the bearing stress is within the allowable limits specified by design codes or standards.
Step 10: Design Verification Perform a design verification to confirm that the moment-end plate connection meets the desired safety and performance requirements. This may involve performing structural analysis or calculations to confirm the adequacy of the end plate dimensions, bolt sizes, and the connection capacity.
Example: Let’s consider the design of a moment-end plate connection between a steel beam and a column. The beam has a maximum positive moment of 150 kNm and a maximum negative moment of 100 kNm. The desired connection capacity is 200 kNm. The material properties are as follows: beam and column yield strength = 250 MPa, bolt grade = 8.8 (yield strength = 640 MPa).
Step 1: Identify the Member Configuration The member configuration consists of a steel beam and a column, both with known dimensions and material properties.
Step 2: Determine Applied Moments The beam has a maximum positive moment of 150 kNm and a maximum negative moment of 100 kNm.
Step 3: Analyze the Structure Perform a structural analysis of the entire structure to determine the forces and moments acting on the connection.
Step 4: Determine Required End-Plate Dimensions Calculate the required dimensions of the end plate based on the applied moments and the desired connection capacity. Let’s assume a rectangular end plate with a width of 300 mm and a thickness of 25 mm.
Step 5: Check End-Plate Shear Strength Check the shear strength of the end plate by calculating the shear stress. For example, if the applied shear force is 50 kN and the end plate width is 300 mm, the shear stress is calculated as follows: Shear stress = Shear force / (End plate width * End plate thickness) Shear stress = 50,000 N / (300 mm * 25 mm) Shear stress = 6.67 MPa Compare this shear stress with the allowable limits specified by design codes or standards.
Step 6: Check End-Plate Moment Capacity Check the moment capacity of the end plate to ensure it can safely resist the applied bending moments. This calculation involves considering the plate’s geometry and material properties.
Step 7: Determine Bolt Size and Spacing Determine the required bolt size and spacing based on the applied moments and the desired connection capacity. Consider bolt shear strength, bearing strength, and spacing requirements. For example, let’s assume M20 bolts with a spacing of 75 mm.
Step 8: Check Bolt Shear Strength Check the shear strength of the bolts by calculating the shear stress. This calculation involves considering the bolt diameter, material properties, and applied shear force.
Step 9: Check Bolt Bearing Strength Check the bearing strength between the bolt and the end plate. Calculate the bearing stress by dividing the applied bearing force by the contact area between the bolt and the plate.
Step 10: Design Verification Perform a design verification to confirm that the moment-end plate connection meets the desired safety and performance requirements. This may involve performing structural analysis or calculations to confirm the adequacy of the end plate dimensions, bolt sizes, and the connection capacity.
Please note that the example provided is simplified, and actual design calculations can be more complex, considering additional factors such as load combinations, eccentricity, plate thickness, and various design code provisions. It is essential to consult the relevant design code or consult with a qualified structural engineer to ensure accurate and compliant connection design.
