Understanding Splice Plates in Steel Structures per IS: 800-2007

Splice plates are crucial components in steel structures, used to connect two separate pieces of a structural element, such as a column or a beam flange, to form a continuous longer member. They are designed to transfer forces efficiently across the connection, ensuring the structural integrity of the member.

The question asks about a specific requirement from the Indian Standard code for steel structures, IS: 800-2007, concerning the area of splice plates used to connect a flange element.

IS: 800-2007 Requirement for Splice Plate Area

According to IS: 800-2007, specifically Clause 8.6.1.1 dealing with splices in tension members, there is a requirement regarding the net area of the splice plates relative to the net area of the member being spliced. While the question refers generally to a "flange element spliced", which could be part of a tension member, compression member, or a beam (flexural member), the percentage requirement is explicitly stated for tension member splices in the code.

Clause 8.6.1.1 of IS: 800-2007 states:

• "The net area of the splice plates shall exceed the net area of the members being spliced by at least 5 percent."

This requirement ensures that the splice connection, particularly the splice plates themselves, have sufficient capacity to transfer the tensile forces without becoming the weakest link. Although this clause is strictly for tension members, the principle of providing slightly more area in the splice plates than the main member is often applied to other types of splices to add a margin of safety and account for stress concentrations or variations in material properties.

The question specifically asks about the area of splice plates exceeding the area of the flange element spliced by at least a certain percentage, aligning with the requirement found in the tension member splicing clause.

Analyzing the Options

Let's look at the given options:

1. 3.50%
2. 1.50%
3. 3%
4. 5%

Comparing these options with the requirement specified in IS: 800-2007 Clause 8.6.1.1, we find that the area of splice plates shall exceed the area of the spliced element by at least 5 percent.

Conclusion based on IS: 800-2007

Based on the provisions of IS: 800-2007, the area of splice plates used to splice a flange element (applying the principle from tension splices as the most direct code provision for a percentage increase) must be at least 5% greater than the area of the flange element being spliced. This minimum excess area provides an additional factor of safety and ensures the robustness of the connection.

Therefore, the correct percentage is 5%.

Revision Table: Key IS: 800-2007 Splice Requirements

Additional Information on Steel Member Splicing

Splicing of steel members is necessary when transporting members longer than standard lengths or when it is structurally beneficial to join multiple segments. The design of a splice connection involves several considerations:

• Type of Member: Whether the member is primarily in tension, compression, bending (flexure), or a combination of forces.
• Location of Splice: Splices are ideally located at points of minimum stress, though this is not always possible. For beams, splices are typically away from maximum moment zones. For columns, they are often located above floor levels.
• Forces to be Transferred: The splice must be designed to transfer all relevant axial forces, shear forces, and bending moments acting at the splice location.
• Type of Connection: Bolted or welded connections are commonly used for splices.
• Code Provisions: Specific requirements from codes like IS: 800-2007 must be followed for design details, bolt arrangements, weld sizes, plate dimensions, etc.

The 5% extra area requirement for splice plates in tension members (and commonly applied in practice to other splices) provides a factor of safety against potential issues like uneven load distribution, slight inaccuracies in fabrication or erection, and potential stress concentrations around bolt holes or welds.