SEAA 3243 Theory of Structures Case Study Semester 1 2025/2026 | UTM

SEAA 3243 CASE STUDY (COMPLEX PROBLEM)

Failure of Continuous Beams in a School

Prologue

In 2005, a new three-story school building was constructed in a small city. The structure was composed of steel framing and consisted of three identical stories. Each story contained six classrooms, as illustrated in Figure 1. In both principal directions, the building comprised three spans, each measuring 7.5 m in length. The typical floor framing plan is presented in Figure 2.

The beams in the X-direction were designed as continuous I-shaped members with identical cross-sections, whereas those in the Y-direction were simply supported with pinned connections at both ends. The continuous beams were designed to resist a dead load of 15.8 kN/m and a live load of 18.9 kN/m, as shown in Figure 3.

Several weeks after the building’s inauguration, noticeable cracks appeared in the gypsum ceiling attached to the soffit of the continuous beams. Upon removal of the ceiling, local buckling and yielding were observed in the top flanges of several beams, as shown in Figure 4. Consequently, the school administration appointed a consulting engineering firm to investigate the cause of the observed distress.

INVESTIGATION INSTRUCTION

Assume that you are appointed as the consulting company to investigate the failure of the continuous beams. The investigation can be resolved through in-depth engineering knowledge using a fundamental-based approach (WP1). Below is the scope of work that you are expected to fulfill.

1. Determine what type of material and structural tests you may need to conduct in order to carry out your investigation.
2. Analyze the continuous beam for the following conditions and draw the bending moment and shear force diagrams for each case. This can be achieved through systematic and theory-based formulation fundamentals in the analysis process of the civil engineering discipline (WK3).Case 1: all class rooms are occupied with students. This is the case in which the continuous beams were designed for. As shown in Figure 3 all dead and live load should be applied on all three spans of the continuous beam.Case 2: only the class rooms between span AB and CD are occupied with students (i.e., class rooms 1 and 3). For this case, the continuous beam should be loaded on all spans with the given dead load, but the live load should be only applied on span AB and span CD.Case 3: only the class rooms between span AB and BC are occupied with students (i.e., class rooms 1 and 2). For this case, the continuous beam should be loaded on all spans with the given dead load, but the live load should be only applied on span AB and span BC.

3. Prepare a report based on the conducted tests and performed analyses. Your report should include followings:

• Compare the bending moment and shear force diagrams of the continuous beam for all three cases and determine the largest positive and negative bending moments and shear forces.
• What are the most probable reasons for the failure of the continuous beam based on the obtained results from the analysis? There is no obvious solution for this task, so you are required to formulate suitable hypotheses using your knowledge and abstract thinking with some originality in analysis (WP3).
• Do you think the columns supporting the continuous beams may be also unsafe? Describe your reasons based on the calculated support reactions from your analysis.
• How can we retrofit the continuous beam to make sure it can safely transfer the forces to the columns?
• What lesson you learnt from your investigations? What is your recommendation to avoid such failures in the future?

FULL REPORT INSTRUCTION

This is a group project. The group members of maximum five (5) people will be assigned by the lecturer in the beginning of the semester. 10% of the total marks from the report and presentation will be carried into the final mark for the course.

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