Learning from Failures


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Learning from Failures

  1. 1. LESSONS LEARNED FROM FAILURE OF CONCERETE STRUCTURES Introduction Studying structural failure case studies is a way of studying the history of the engineering profession. Typical calculations for design are based on predicting and avoiding failure. The factor of safety is used to avoid failures, but knowledge of past failures will better equip an engineer to steer clear of future failures. It is not only important to know what caused the failure, but also to understand how it occurred and how to avoid the problem in the future. This failure study will make you a better Structural Engineer.
  2. 2. VASUDEO PANDYA P.E. ; S.E. • Family Status: Married • Educational Qualification : • • B.E. (Civil) Birla Engineering College (BITS), Pilani MS (Structural) University of Wisconsin, Madison, USA • Professional Career Summary: • I have worked on large Oil Refinery and Thermal Power Plant Projects for last 25 years in USA. • Professional Achievement/special knowledge: • • License Professional Engineer (P.E.) License Structural Engineer (S.E.) in U.S. • Special Interest: • Peer Review/Checking (Structural ) of projects designed in house or designed by out side consulting companies. Sharing my experience with you Young Engineers (Mentoring).
  3. 3. Professionalism in Engineering Here I produce Professionalism as defined in "Recommended Guidelines For The Practice Of Structural Engineering in California". Fifth Edition September 1999. By Professional Practice Committee of Structural Engineers Association Of California (SEAOC), Section 2 , Pages 1-2 thru 1-4. 2. PROFESSIONALISM 2.1 General: The essence of professionalism is integrity and honesty. Engineers should maintain ethical and professional standards when performing structural Engineering Services. 2.2 Obligation to the Public: When performing structural engineering services, an engineer should: 2.2.1 Endeavor to protect the general health and safety of the public, as well as fulfill obligations to clients. 2.2.2 Perform services only within the engineer’s area of expertise. 2.2.3 Perform services in an objective, honest, and impartial manner, basing decisions on education, analysis, knowledge, experience, and sound engineering judgment 2.2.4 Issue public statements in an objective and a truthful manner. 2.2.5 Refer deceit, misrepresentation, violation of contract, fraud, negligence, or incompetency of others performing Structural Engineering services to the Board of Registration for Professional Engineers and Land Surveyors. An objective and unbiased approach to referring such acts to the Board of Registration is important. 2.3 Obligation to the Client: When performing structural engineering services, an Engineer should: 2.3.1 Act faithfully and honestly in the client’s best interest, and respect the confidentiality of information obtain from, and on behalf of, the client.
  4. 4. Professionalism in Engineering ….. Continue 2.3.2 Disclose to the client real and potential conflict of interest prior to performing services for the client, thus offering the client the opportunity to decide whether a conflict of interest would be detrimental to the interest of the client. 2.3.3 Solicit professional assignments in an ethical and professional manner. 2.3.4 Accurately represent the engineer’s qualifications and experience. 2.4 Obligation to the Profession: When performing Structural Engineering services, an Engineer should: 2.4.1 Uphold the integrity and dignity of the profession. 2.4.2 Perform professional services with honesty and fairness. 2.4.3 Actively support professional societies and organizations dedicated to the advancement of knowledge within the profession. 2.5 Obligation to Colleagues, Employers , and Employees: When Performing Structural Engineering services, an engineer should: 2.5.1 Act with fairness, honesty, objectivity, and respect in relationship with other engineers. 2.5.2 Recognize and respect the professional contributions of Colleagues, employers, and employees. 2.5.3 Render an opinion of the work of another engineer based upon an unbiased, comprehensive evaluation of the work, recognizing that there may be alternate methods used to achieve acceptable results.
  5. 5. Emerging Issues in Structural Engineering • Emerging Issues • • • • Structural engineers have a uniquely significant responsibility for protecting the public relative to the other design disciplines. Architectural, mechanical, and electrical system failures usually result in unattractiveness, poor functionality, discomfort and/or inconvenience. A structural system failure almost always has more serious consequences, even in the best cases, there are often substantial costs associated with correcting what is or could become a life-threatening situation. As a result, professional liability insurance rates for structural engineers have been increasing, leading to the creation of the Risk Management Program (RMP). In addition, efforts are underway to establish board certification at the national level and expand separate licensure at the state level to "raise the bar" of qualifications to practice structural engineering. Blast resistance , Progressive/Disproportionate collapse, of structures. Fire resistance design of structures. Learning from failure/ collapse of structures.
  6. 6. RESPONSIBILITY OF A STRUCTURAL ENGINEER OF RECORD (SER) For a time being think that you have your consulting firm in some city in USA. In USA as compared to India, Liability Laws are very strong. That’s my opinion. You firm designed one of the three recently failed structures (See recent postings in SEFI) in India. 1) A Chimney Failure. 2) A Coal Bunker Failure. 3) Jalandhar Factory Collapse. 20 died, 75 Injured. Client ( Owner) of these Plants will sue your firm. There will be expert witnesses in the court. Finally Court decides that this was a Design/Detailing flaw. Court will order Heavy penalties (Money awards for damages). Also you as a HOD(Civil/Structural) or MD of your firm will loose your P.E. or S.E. license to practice Structural Engineering. With this, my best guess is you will not be in business of Structural Engineering anymore . Sorry to point such a bleak picture but this is the way Structural Engineering is practice in USA. Liability, taking responsibility of mistakes and when required paying heavy court fines are always expected from us engineers. So my advice to you is when you submit a project proposal have enough Man Hrs to implement Quality Assurance using these Industry Standards from USA.
  7. 7. Failure of Structures Education in India • FAILURE OF STRUCTURES EDUCATION. With the attached web link and attach file see need for such FAILURE OF STRUCTURES EDUCATION in Indian Universities for B.E. (Civil) and M.E (Civil) and also for professional/working civil engineers like us. http://www.structuremag.org/article.aspx?articleID=336
  8. 8. Failure of Structures Education (Courses) and Problems in India • 4th April 2012 Learning from failures is a very important facet of engineering education. Unfortunately, this is ignored in all our engineering colleges, the IITs included. It's high time this gap is bridged. • Indrajit Barua.
  9. 9. Failure of Structures Education (Courses) and Problems in India • From a posting in SEFI by Prof. Arc. “I agree with you 100% that it is very useful to know why a structure has failed as important results are learnt from such studies. The problem [definitely in INDIA] is such information may not be available for wide circulation fearing witch hunt. There has to be legal immunity If you have access to any information on failure of structures in INDIA, please provide web link”.
  10. 10. Failure of Structures Education(Courses) and Problems in India • Dear SEFIANs,i tried to get hold of a failure report of one of the chimney failures in India. The report is in the safe hands of police and judiciary but is never allowed to be seen by engineering fraternity. And everybody expects failures should be mitigated. • regards murali
  11. 11. Failure of Structures Education (Courses) and Problems in India • The bunker of the 6th unit of the Kahalgaon Thermal Power Station in Bhagalpur district collapsed on Sunday halting power generation from the unit with 500 MW capacity. Source : News Report regards bijay sarkar
  12. 12. Delhi Metro Concrete Pier Failure I found this important recent failure in India from Google web search. This DMRC failure was also published in ENR (Engineering News Record) of USA. Delhi Metro Mishap: DMRC, Gammon Responsible. The four-member panel that went into the July 12 Metro mishap has fixed responsibility on the DMRC and contractor Gammon for the accident and recommended the reconstruction or modification of four pier caps near the Zamrudpur construction site. In a 11-page report, the panel headed by IIT Professor A K Nagpal said, there was a departure at site from the requirements of the design in the application of grout to the interface between the end plates of the steel strut and the face of the pier/pier cap to which the plates are attached. "The drawings followed on site for construction of Pier 67 were advance copies and not authenticated by DMRC's design section. On enquiry, it was found that on occasions work commences without 'Good for Construction' signed drawings to avoid delayed construction," the report said. It also recommended the "reconstruction of or modifications to pier caps 54, 66, 67 and 68 to a revised design configuration." The July 12 incident at Zamrudpur where an under-construction metro bridge collapsed due to "design fault" in pier 67 killed seven people. The panel also asked the DMRC to strengthen its design review system to ensure that rigorous checking of special structures is carried out in future and that certified drawings are made a prerequisite for construction to proceed.
  13. 13. Delhi Metro Concrete Pier Failure …… continue The report also said that unconditional "no objection" was not obtained for the permanent works drawings prior to construction, which should have been the practice for structures of such a special nature. "The contractor (Gammon India) did not ensure that 'good for construction' status with appropriate certification by DMRC was achieved prior to constructing the works," the report said and added that there is concern regarding the sample test recording by the contractor and witnessing of the same by DMRC. "The consistency of concrete sample test results is highly abnormal. This raises doubts over the authenticity of the records submitted," the report said. The panel concluded that deficiencies in material, design and failure to carry out material testing at the time of appearance of the first cracks and deferral of the load test were the causes of the accident. It also said both the temporary works and permanent works designers should be required to check the material and workmanship of special structures at site to certify compliance with design intent prior to application of loads on temporary works assemblies and prior to pouring concrete at permanent works locations. Show Reliance Industries Slides.
  14. 14. Earthquakes and Structural Engineers • Relate this to Bhuj Earthquake of 2001 in Gujarat: • http://www.pptnetwork.net/?query=bhuj+earthquake+ppt • Dear SEFIN'S: I watch "NDTV" documentary today 23/09/2011 evening "Agar Delhi Hili Hoti". That was for a Structural Engineer like me walking through a dangerous land. That was riveting. Work is cut out for us. What else to say. We should all ask for a copy of it and see it. Delhi is Seismic Zone IV and that TV documentary scare's me, a Structural Engineer like nothing else. TIMES OF INDIA " Editorial " on Earthquake preparedness says it all, Titled. WAKE UP CALL: Sep 21, 2011, 12.54am IST
  15. 15. Earthquakes and Structural Engineers.. Continue • TIMES OF INDIA " Editorial " on Earthquake preparedness says it all, Titled. WAKE UP CALL: Sep 21, 2011, 12.54am IST Himalayan Earthquake With the death toll climbing to at least 80, the recent Himalayan earthquake is an urgent wake-up call for all concerned — the government, policymakers and law enforcers. The effects of the 6.8 magnitude earthquake were felt across as many as six northern and eastern Indian states. The scale of devastation in its trail has raised critical concerns about India's preparedness to deal with quakes of much greater intensity. That Japan experienced earthquakes this year measuring 8.9 on the Richter scale — releasing energy a thousand times greater than the current Himalayan quake — should serve as a sober reminder. Given that over 58.6% of land in India is vulnerable to tremors, the National Disaster Management Authority (NDMA) has identified quakes as a major issue of concern. As many as 38 of India's cities, including Delhi, Kolkata, Mumbai, Chennai, Pune and Ahmedabad, fall within moderate-to-high risk seismic zones. Put simply, an earthquake on the scale that Japan experienced would lay waste whole cities here. It is well known that quakes do not kill people, buildings do. Safety essentially lies in ensuring quake-resistant construction of buildings. There already exists a host of safety regulations on paper. The NDMA has mandated all new constructions to be earthquake-resistant, especially in seismic zone cities.
  16. 16. Earthquakes and Structural Engineers.. Continue Earthquake engineering codes and quake-safe construction guidelines have been laid down by government bodies. But the real worry is about their enforcement. Illegal and poor quality constructions continue to be the bane of urban India, coupled with a crippling lack of awareness regarding safety norms. Structural engineers have criticized city authorities for flouting regulations and risking lives. Behind the shoddy construction is murky collusion between real estate and municipal authorities, mired in corruption and rule bending. India needs to draw lessons from Japan, which has stringently enforced strict building codes, put into effect a functional warning system and conducted regular drills among people. The Himalayan quake is a reminder to get our act together. Besides enforcing building codes, important infrastructure such as arterial roads and airports needs to be fortified. Community-level preparedness could drastically reduce the loss of lives and property. Education and information are two vital conduits for spreading awareness. The government`s resource material on quakes should be widely disseminated and discussed at every forum, starting with schools. Disaster management is already part of the social sciences school syllabus. Regular drills can help prepare children to deal with sudden situations. It is the extent of disaster preparedness which will help India protect itself from quake devastation.
  17. 17. Failure of concrete Structures….. Tower of Pisa Introduction The Leaning Tower of Pisa is the freestanding bell tower of the cathedral of the Italian city of Pisa. It is situated behind the Cathedral and is the third oldest structure in Pisa’s Cathedral Square. The tower is about 60 m (200 ft) tall from foundation to belfry, 19.6 m in (66 ft) in diameter and weighs approximately 145 MN (14,500 tons). Its foundation is inclined at almost 5.5 degrees to the south; the tower overhangs the ground about 4.5 m (20 ft) out of plumb. Today its inclination is about 10%; the value corresponding to the eccentricity on the loads on the foundation is 2.3 m. Lessons The failure of the Tower of Pisa is without doubt unique for a number of reasons ranging from the fact that it is a failure that has been occurring essentially on a continuous basis for more than 800 years. Despite the extensive investigations and analyses conducted over the past 60 years, there is still no consensus on the cause of failure. What is significant however is that finally, after 8 centuries, the condition of the tower has been improved. For more details use web link… • http://matdl.org/failurecases/Building_Collapse_Case s/Tower_of_Pisa
  18. 18. Failure of concrete Structures….. Introduction Studying structural failure case studies is a way of studying the history of the engineering profession. Typical calculations for design are based on predicting and avoiding failure. The factor of safety is used to avoid failures, but knowledge of past failures will better equip an engineer to steer clear of future failures. It is not only important to know what caused the failure, but also to understand how it occurred and how to avoid the problem in the future. In the collapse at 2000 Commonwealth Avenue, Boston, Massachusetts on January 25, 1971, punching shear failure is believed to have triggered the collapse of two thirds of the 16-story concrete building during construction. But an investigation called for by the mayor proved that there were many flaws in the design of the apartment building. It is important to remind engineers about past failures, such as this one, so that history does not repeat itself.
  19. 19. 2000 Commonwealth Avenue, Boston Massachusetts (January 25, 1971) Failed Building Designed Building
  20. 20. 2000 Commonwealth Avenue, Boston Massachusetts (January 25, 1971) SHEAR MECHANISMS AND FAILURES Shear in reinforced concrete can be a complex subject for students to grasp. First of all, the flow of forces can be difficult to visualize. Second, while the need to use stirrup reinforcement to enhance shear strength is straightforward, the need to provide minimum stirrups when the calculated forces show that they aren’t necessary is not so obvious. Two case studies illustrate the collapse of buildings under construction due to punching shear and similar mechanisms. The first of the two was the January 25, 1971 collapse of the 2000 Commonwealth Avenue apartment building under construction in Boston. Four workers were killed in this collapse. The project was characterized by an almost total lack of construction control and inspection. The floor plan and the extent of collapse are shown in Fig 1.
  21. 21. 2000 Commonwealth Avenue, Boston Massachusetts (January 25, 1971) This building used flat plate construction. A plate is a slab of uniform thickness supported on columns. This is a very economical type of construction for short spans and light loads because formwork is very simple and the absence of beams reduces the floor-to-floor height (p. 606, Wight and MacGregor, 2009) 3. However, the problem with the system is that it is subject to two-way or punching shear of the slabs, which can be a brittle failure mechanism. Despite the importance of this failure mechanism, textbooks often suggest that the material not be covered in an introductory course but be deferred to an advanced course. Prof. Delatte The punching shear mechanism is illustrated in Fig. 2. The slab breaks away and the column “punches” through the slab. The resistance to punching shear depends on the strength of the concrete, the effective depth of the slab, and the perimeter of the failure plane around the column. Clearly, the loads applied to the slab and the removal of shoring under the slab are also important. In the collapse at 2000 Commonwealth Avenue, the strength of the concrete was low and strength development was impaired by cold weather. Some of the reinforcement was improperly placed and poorly developed. The roof slab of the building held heavy mechanical equipment, and there was evidence that shoring had been removed prematurely.
  22. 22. 2000 Commonwealth Avenue, Boston Massachusetts (January 25, 1971) Lesson learned: Unfortunately, 2000 Commonwealth Avenue would not be the last project that suffered from faulty construction practices leading to a punching shear failure and progressive collapse of the building. Skyline Plaza was one of the first major failures to follow Commonwealth Avenue. Similar to the collapse in Boston this 30 story concrete structure failed due to early removal of shores, insufficient concrete strength, and improper construction planning. Harbour Bay Condominium was another case of a building project that resulted in a collapse during construction. Again procedural errors were largely to blame leading to a punching shear failure and progressive collapse during construction. Immediately following the collapse a summary of the failure at Commonwealth Avenue was available but the details were not widely known. Skyline Plaza and Harbour Bay both could have benefitted from the timely dissemination of information about this failure. For a further discussion of similar failures please review Concrete System Collapses and Failures During Construction. For more details use web link… http://matdl.org/failurecases/Building_Collapse_Cases/2000_Commonwealth
  23. 23. Building Collapse Cases/Skyline Plaza at Bailey's Crossroad
  24. 24. Building Collapse Cases/Skyline Plaza at Bailey's Crossroad Introduction: On March 2, 1973, the Skyline Plaza apartment building in Bailey’s Crossroads, Virginia collapsed while under construction. The collapse extended vertically through the building from the 24th floor to the ground, leaving an appearance of the structure as two different high rise buildings with a gap between them. The collapse tore a sixty-foot (18 m) wide gap through the building all the way to the ground. At the time of the collapse, two practically identical reinforced concrete towers had already been built (Kaminetzky 1991, p. 64). The collapse occurred at about 2:30 pm (Leyendecker and Fattal 1977 pg. 2). Structural Analysis: At the time of the collapse, three dimensional elastic finite element (FE) analysis using computers was still a relatively new technology. The NBS investigation team used FE analysis to evaluate the slab stresses in the region where the collapse occurred, using beam and plate elements. Stresses were compared to the provisions of ACI 318-71 (ACI 1971). Three different cases were analyzed, with different shoring and concrete conditions. Yield line analysis was also used. The results showed that even with low concrete strength, a flexural failure of the slab would be unlikely. However, under any of the cases where shores had been removed, a punching shear failure of the slab would probably occur. Once punching shear occurred at any one column, the collapse would rapidly propagate as other slab-column joints became overstressed. There was no indication that the crane was a contributing factor to the collapse (pp. 65 – 83, Leyendecker and Fattal, 1977). It should also be noted that by the ACI code (ACI 1971), sand-lightweight concrete has a 15 % lower shear strength than conventional concrete for the same compressive strength. The most critical locations for punching shear were found to be at columns 67, 68, 83, and 84 (Carino et al., 1983)
  25. 25. Building Collapse Cases/Skyline Plaza at Bailey's Crossroad Lesson learned: “The NBS investigation concluded that the probable cause of the collapse was a punching shear failure of the 23rd floor… The premature removal of forms supporting the 23rd story slab when the concrete of that slab had a relatively low strength produced shear stresses in excess of the concrete capacity at the time of the incident… Most of the eyewitness reports indicated deflection in the 23rd and 24th story slabs [varying from 6 in. to 2 ft. (152 mm to 0.6 m)] which increased over a 15 or 20 min time period before failure… The loss of support from any one of these columns led to overstressing of the slab around the remaining columns and the failure propagated through the 23rd floor until a stable configuration remained. The accumulation and impact of falling debris from the collapsing 23rd and 24th floors overloaded the 22nd floor slab and induced the progressive collapse of successive floors down to the ground” (Carino et al. 1983, p. 41).
  26. 26. Building Collapse Cases/Skyline Plaza at Bailey's Crossroad Lesson learned: (continued….) Kaminetzky (1991, p. 67) cites six lessons from this case: The contractor should be responsible for preparing formwork drawings, including shores and reshores The contractor should prepare a detailed concrete testing plan for stripping forms, including cylinder tests Inspectors and other quality control agencies should verify that the contractor performs the above two items The EOR should make sure he/she provides the contractor with all necessary design load data and other unique project information “Uncontrolled acceleration of formwork removal” may cause a total or partial collapse Continuous top and bottom slab reinforcement is necessary around the columns. Continuous reinforcement provides overall ductility. If the contractor uses cylinder tests to determine when to strip forms during cold weather, the cylinders should be stored at the same ambient temperature as the structure. This will prevent overestimation of the in-place concrete strength. For more details use web link… http://matdl.org/failurecases/Building_Collapse_Cases/Skyline_Plaza_at_Bailey%27s_Crossroad
  27. 27. WEB LINK FOR MORE FAILURE CASES • WEB LINK FOR MORE FAILURE CASES : SELECT THE FAILURE CASES AND STUDY WELL. Will make you a better Structural Engineer. Try to collect reliable information on Failure of Structures in India (Chimney’s , Coal Bunkers, Buildings) and learn from them. • http://matdl.org/failurecases/ • Show ACI SP-284-4 slides. Learning from Failures in Concrete Design and Construction. By Dr. Norbert Delatte .
  28. 28. Thanks. • Thanks for listening. Best wishes for your career.