Effect of Directly Welded Stringer-to-Beam Connections on the Analysis and Design of Modular Steel Building Floors

Modular Steel Buildings (MSBs) are fast evolving as an effective alternative to conventional on-site steel construction. An explanation of the concept of modular steel design, including its unique detailing requirements is given in this paper. The paper also focuses on a typical MSB floor system which is achieved by welding the webs of the stringers directly to the floor beams. A typical modular floor grid structure is designed using conventional methods. The floor is then modelled using the finite element method and analyzed under the effect of dead and live service loads. This allows an assessment of the effect of direct welding between stringers and floor beams on the analysis and design of floor beams, stringers, and welded connections. The results reveal that consideration of the true behaviour of direct welding leads to a distribution of forces and moments which is different from those found in conventional steel buildings. A simplified analytical model is proposed to capture such behaviour. Regression functions have been developed to describe the model. In practice, the proposed model can predict the actual forces and moments, leading to a reliable design of modular steel floors.