Structural Assessment of Steel Frame

Task and Mark distribution:

IMPORTANT: You need to model the 2D frames according to the data given to you in Appendix A, use the set of data to discuss and conclude according to the brief requirements.

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The structural is a steel frame for an old warehouse built before the Second World War. The 2 dimensional steel frame as shown in Appendix A is a simplified model to represent the warehouse. To simplify this exercise, the variable loads as indicated is the only load condition you are required to consider. Description of the structure, assumptions and modelling data are given in Appendix A.

Your task is to model the steel frame in the given structural analysis software package, Midas Civil, without application of any safety factor. The report should be structured to the following three parts:

Part 1 – Modelling of steel frame without damages

Model the original undamaged structure as a 2D frame. The following should be reported: the bending moment and the shear force diagrams for all column and beam members; the axial forces in all columns and bracings; horizontal deflection at the top of the structure. Indicate the “significant values” in the diagrams.

Please save the software project file with a name of “Group number_modelA”.

Part 2 – Modelling of steel frame with damages

Repeat the modelling exercise in Part 1 with the following modifications to represent damages:

1. The beam to column connections marked as “D” (for damaged) become a pinned connection due to bolt failure caused by corrosion instead of original rigid connection.
2. The column bases marked as “D” is no longer rigidly connected to the pad foundation but only “pinned” to the foundation due to damage to the stiffeners of the connections caused by corrosion.

The following should be reported: the bending moment and the shear force diagrams for all column and beam members; the axial forces in all columns and bracings; horizontal deflection at the top of the structure. Indicate the “significant values” in the diagrams.

Please save the software project file with a name of “Group number_modelB”.

Part 3 – Parametric Studies and discussion

NOTE: No capacity check according to design code is required since the strength of the material is unknown. You should assume that the given structure without damage is able to take the bending moments, shear forces etc found in the undamaged structure model in Part 1 above.

⦁ Identify the minimum capacity of the structural members as indicated from the results of the undamaged structure in Part 1.
⦁ Identify the maximum axial force, shear and bending moment applied to the structural members of damaged structure.
⦁ Compare the findings in (i) and (ii) above and identify the most likely failure condition for each mechanical factor of bending moment, shear force and axial force.
⦁ Explain how the load path is changed by the damages leading to the risk identified above. Comment on the amount of horizontal deflection before and after the damages.
Part 4 – Verification and Conclusion

By using hand calculation method, for the undamaged frame, calculate the bending moment distribution of the 1st floor internal beam member and for the damaged frame, calculate the bending moment distribution of the 1st floor edge beam at the right side (see Figure 1, Appendix A). Compare the results from the hand calculation with the corresponding results from the computer analysis. Discuss why the results are different and if you can conclude that the computer analysis is likely correct.

Mark Allocation

Correct modelling of the frame (with and without Damages) 15
Appropriate, accurate and correct presentation of the results 20
Parametric Studies and Discussion 40
Verification and Conclusion 15
Quality of presentation of the report incl. use of Technical English 10
Total 100