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Structural Failures | Building Failures

Learn from mistakes made by others so you will not make the same for your projects

 

A look at Structural Failures of the Sports Stadium at Kuala Terrengganu, Malaysia, and How to avoid Structural Failures

It was reported in June 2009, in Kuala Terrengganu, Malaysia, that the roof of a RM300 mil (US $90 mil) Sports Stadium collapse suddenly just after it was recently completed.

No one was injured, The damage was extensive, as practically the whole east wing came crush down at 8am in the morning, a few cars were damaged. The contractor was a South Korean Company while the Consultants were local Malaysians. The Repairs were carried and costs about RM35mil (US$10mil).

Since the works were still within the defects liability period which is usually 12 months or more for such a massive project, the cost of remedial works were borne by the Contractor. What other issues involved would be under the relevant authorities.

An Investigation Committee was immediately set up with involvement from the Public Works Department, Ministry of Works, Related Agencies, Experts, and an extensive report was later compiled.

Some of the photographs of the roof stadium collapse would be revealing :-

 Aerial View of Collapse Roof

 

Aerial Picture of the Collapsed Roof. Note that the other structures are intact, it is only the roof which failed and the roof is actually a Proprietary Space Frame Structure, and not designed and fabricated by local contractors on site. Note also that Space Frames are all Pinned Jointed and designed based on direct forces, tension or compression.


Collapse Space Frame Roof 

Part of the Roof Structure which shows the Space Frames involved



 Collapsed Roof Came Crushing Down

More pictures showing the extensive collapse of the whole roof.

Note that Space Frames are interdependent on each other for strength. It is very weak and unstable until it is erected and forces are transmitted from top down. It is also very sensitive and any failure would be more of a "domino effect"



Roof Collapse on Stadium Seating 

Extensive Lives would have been lost had the Sports Stadium been occupied during the Malaysia Games !

Designers and particularly Structural Engineers must be acutely aware that any structures you do must never fail under any circumstances, as any failures could result in collapse and lost of lives, not to say very costly.



Part of Roof Collapse 


 Space Frame Collapse

Proprietary Space Frame

Causes of Collapse of the Roof Structure

The Reports by the Investigation Committee highlighted a few factors which could have contributed to the failure of the roof structures as summarised below :-

  • The design was inadequate 
  • The roof was not erected properly resulting in misalignment
  • No quality control on Site
  • Materials and Workmanship not in accordance to specifications 
  • Alternative designs from Contractor was adopted without proper analysis

The above sounds too familiar and so common in our construction industry. Almost every sites are faced with these issues. In fact, structures are very resilient and would not have been catastrophic in collapse, even if under designed. The concept of limit state design takes account of this, allowing collapse to be progressive rather than catastrophic. Only steel framed structures are more prone to collapse especially during erection period, and particularly for 3D space frame structures.

The BIG Question is "Who is responsible for this?"

It is natural for everyone to point at the Contractor first and then the Consultants, but in many cases the Employer or Owner are to be blamed. Investigations can never be final and the cases will drag on for ages usually to the courts. The best approach is to AVOID this ever happening to you and your projects, whether you are a Contractor, a Consultant or an Employer. In almost all cases, this can be avoided.

Take a Vote
 

 

How to Avoid Structural Failures for your Projects?

As a Civil Engineer & Structural Engineer for the Project :-

  1. Do not over use software in Engineering or Structural Analysis unless you know exactly what you are doing. Software are very complex tools, and may not be correct. If you ask the software vendor if there is any warranty that using their software will not cause collapse, chances are nobody will give you that guarantee. So whether you use it correctly or wrongly, the risk is on yourself. Use software only for alternative checks and analysis, and comparative designs or for designs of a similar structure which you already know works correctly. Unless you are familiar with normal calculations and analysis that your were taught in Universities, and have some real working experience in manual approach, avoid software tools. In short, software are for experienced engineers only, and never for green horns. In the case of the Collapse of the Stadium Roof above, manual calculations should have been performed for key structures, and complimentary, additional analysis by proprietary software in 2D & 3D, performed by specialist only. Use of excel, mathcad, or any spreadsheet and self programmed software like autolisps, visual basic, etc, are all recommended.
  2. Always look at Structural Forms, Shapes and Overall Stability. This is part common sense, part experience and part engineering. Trusting your sixth sense would be an added advantage. If there is something wrong in the design or construction take a second or third look, and consultations with your peers if you must, to ensure you get a good sleep.
  3. Be aware that stability is 3D while most engineering analysis is 2D. Even a lattice girder is a 3D structure even though we design in 2D. Ever heard of a Two Legged Table? Never, its always 4 legged or 3 legged to be seated and stable. So think 3D. The above Roof was constructed using Space Frame made of tubing and pinned jointed. This is 3D design, and behave more like 4D. why 4D? because it is still Unstable in 3D and would require supports fixed in position before it is stable. So take great care with 3D structures with 4D collapse mechanism.
  4. Always Check Drawings produced by draftsman in autocad form and printed form, not once but several times particularly on critical structures. Check also drawings released to contractors because with ease of cad system, changes could be accidental.
  5. Ensure that you Supervise Full-Time On-Site. Some employers or clients want to supervise themselves or even not at all. In this case you have to make sure that they understand that in so doing, they are responsible for any failures and mismanagement. Some employers want to save money by using their own manpower (usually without design or construction experience) to do "management" supervision works themselves. This is a wrong, irresponsible thinking and sadly, some large corporations and government agencies are still doing this without understanding the risks involved for their staff, the public and the projects. Ad-Hoc or Part-Time Supervision is flawed in everyway and cannot be justified under any circumstances !
  6. Let specialist do specialist Works. This is the most common flaws in our construction industry. There are General Contractors and there are Specialist Contractors. If you are supervising the works, make sure contractors use specialist where required. As an example, had the roof space frames be designed, fabricated, erected, commissioned by specialist then it would not have collapse! What constitute specialist works? You will need to define clearly in the contract documents early, include Proprietary Products & Services.
  7. Do not accept Contractor's proposal unless you are able to carry out extensive evaluation yourself. Many Contractors come with proposals for changes which can involve structural changes or non-structural such as using alternative materials. Changes can be good if done with good intentions and to solve problems at site. Structural changes should be carefully checked by yourself. If it involves proprietary structures such as engineered steel, space frames, slip forms, prefabricated sections, pre stressing, etc, they should be carefully studied. A proposal by contractor to have his own changes stamped and certified by an engineer is not good enough unless the credibility of the engineer can be assessed. The ultimate goal is to ensure that your designs are not abused as you will be responsible at the end of the way, no matter what the employer, owner or contractor do. Bear in mind that you are the expert here.
  8. Always recheck your designs compared to site conditions during the time of construction. This is important as in many cases, site changes in itself, or the surroundings may make your design criteria obsolete which can happen.
  9. Design for the Future - All structures are designed with a life span of at least 50 to 100 years or even must be stable "forever". Most engineers would not look beyond the site environment, so would only include conditions within the site and not outside the site. You can develop your own site but be aware that the surrounding development will affect your structures equally, and predicting what will occur in future is part guesswork and part intellectual research. E.g was the case of the Highland Towers collapse where changes in the hill side conditions cause massive soil slips, toppling the Highland Towers.
  10. Be Conservative in Design - there are many engineers who try to be real smart by designing everything based on collapse or limit state and using limiting factors of safety such as those below 1.6 and 1.4. Some structures which are difficult to analyse or visualise would require more conservative factor of safety such as 2 or 3. Perhaps a new approach using Factor of Uncertainty should be introduced into the design criteria to allow for complex structures. Even Retaining Wall design is a complex structure due to earth pressures uncertainty so a factor of safety of 2 or 3 would be reasonable for overtopping or sliding failures.
  11. Use Standards & Established Methods & Procedure when carrying out Calculations and Designs. Building Codes must be followed, and let no one, except your peers to influence your engineering judgement, bear in mind there are always too many happy critics jumping on your back.

 

Design of Large Spans Structures using Space Frames

Space frame is rapidly gaining popularity as an efficient structural system for very large spans such as aircraft hangers, manufacturing plants, airports, sports stadium, etc. These space frames designs use high strength steel components usually tubes and jointed via pinned connections to form any shapes, some very complex. It is usually pre-fabricated and easily assembled on site. An incredible achievement.

Designed and constructed properly it is an advanced engineering form for the future.

 Design Examples fo Space Frames

Design Tips

"This picture shows a design which would have been the correct Structural Form for the Sports Stadium Roof - a Main Cantilever Truss Girder, with roof sheeting supported by triangular space truss, or simple C-channels. A much simpler structural analysis with 2D design approach"

- MEC Engineers

Possible Structural Forms for the Sports Stadium

Stadium Roof Plan.

Plan of Stadium

An Arched Roof (complex shape), supported by Proprietary Space Frame (yellow), which in turn carried by Cantilever Lattice Frame (green).

Section of Stadium

Cantilever Lattice Frame (green) can be Main Beams supported by the Stadium RC Wall, Proprietary Triangular Space Frames (yellow) can be spanning between the Main Beams. Simple Structural Form, easy to ensure analyse and design.

Design Methods

Use Simple Statics for Cantilever Lattice Beams, and Proprietary Software for Triangular Space Frames

- MEC Engineers

Some Design Considerations

 lattice frame designed as fixed joints

Type A-Design - Lattice Cantilever Frame can be designed as Fixed Jointed Frame. A simple Bending Moment can be plotted. The top chord will be in tension and bottom chord in compression. The diagonal chords will be in tension and compression alternately. You can assume a cross section where the top and bottom chords act like top and bottom flanges of an I-beam while the cross members act as web of I-beam. This design approach would give greater rigidity, less deflection. Circular hollow sections should be used with thicker walls and all welded joints to be full.

 

 lattice frame designed as pinned joints Type B Design - Here the Joints are all Pinned and forces/loads from the roof are assumed to be transmitted through the joints. This is the normal approach to design. The pinned joints are bolted. It is unstable unless supported in the 3D direction. You can use double C-channels, L-Angles or I-sections.
 

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Authur- Philip Goh (B.Sc, MIEM, P.Eng. MICE, C.Eng) MEC Engineers, Civil & Structural Engineer HP: 016-8672189, Email: Widget: email cloaker