(Part I appeared last Friday, 5 October 2007)
Different phases of collapse: Different phases of the collapse sequence caused by the removal of the northeast corner column were studied by simulation. The analysis showed that due to this support removal, hinges start to form at the slab-column connections in a gradual fashion starting from the top storey. However, formation of such hinges up to Phase 4 were found to be mostly concentrated in the topmost four stories, except the north-east bays where hinges were found to be developed in all storey levels. This largely matched with the Observation Bases formulated during the Investigation, indicating the closeness of the simulation results with the real phenomena that took place at those sad hours.
Committee's remarks about the failure: Based on these findings, the investigation team was able to derive the following conclusions:
- The failure of the northeast corner column is responsible for triggering the collapse of the structure at that fateful night.
- Upon the triggering, the hinges started to form at slab-column connections at top storey levels pushing the upper floors to fall in a sway motion towards east and northeast direction. A mild sway of the southern side columns to southward direction also took place.
- The collapse of the upper floors caused a tremendous vertical impact on the lower stories, which action caused the lower stories to come down vertically. Falling of the lift core added the final blow.
- Northeast corner bays of the structure collapsed vertically at all floor levels.
North-East Corner Column showed very poor concreting: The push over analysis suggested that the failure is related to the movement of the northeast corner column of the building and also it was apparent from the cleared area of the building that this corner has gone down by about 11 feet from rest of the slab. With the help of the construction firm M/s. Development Constructions Limited this corner was further exposed by manual excavation.
Some serious construction problems were observed in the northeast corner column of the building, which made it clear how the collapse of the whole building was initiated. It was clear form the excavated portion of the pile cap that the position of the cap was intact. For about 2 feet of the column above pile cap, the column reinforcement buckled and twisted. The concrete at this portion was very weak and contained clay and other deleterious particles. The concrete was so soft that aggregates would easily be pulled out with bare finger. This suggests that although sufficient care was taken in casting the pile cap, the column at this portion was perhaps cast under water that contained significant mud and other loose materials and remained weak. There were twelve 25 mm diameter high yield reinforcement bars that perhaps carried the load of the building but due to sustained creeping these ultimately buckled that lead to the collapse of the whole building.
It's evident from the circumstances that the standard civil engineering procedure has not been followed in this building. Although there had been some flaw in the design consideration of the building, but it is the careless supervision of the construction at column base level that had initiated the catastrophic failure.
The failure incidence trapped people who were working inside the collapsed building at that fateful hour. In order to rescue the trapped people it was necessary to remove one slab after another from top. But because of heavy weight and bulk and their reinforcement connections it was not easy to separate the slabs and pull them out. Therefore the rescue team cut open hole into the slab and removed it to get people out. But it was a time consuming process as these openings were made by drilling into the slab to form smaller pieces capable of being lifted by three cranes brought for the purpose. Capacities of these cranes varied between 120 and 60 tons. All these removal process took about eight days. Perhaps many lives could have been saved if there were demolition chemicals or rapid concrete disintegrators available at the time of rescue.
Who are responsible for the Polashbari failure incidence?
If one traces the whole process leading to the catastrophic failure, a list of inappropriate actions or inactions can be listed, each having a direct or indirect consequence that has contributed to the failure. A few are listed below:
- Did not obtain permission for constructing 9-storied building from appropriate authority.
- Did not have the knowledge of selecting an adequately qualified engineer to design the structure.as unaware of implication of not appointing a qualified/experienced contractor for execution of the job.
- Was unaware of the necessity of quality assurance system for such a critical structure.
- Made faulty design considerations such as live load, superstructure system, inadequate consideration for lateral loads, etc.
- Did not provide detailed drawings for all connections
- Did not get his designs checked by another qualified engineer or advise the owner in this regard.
Failed to ensure materials specifications, structural dimensions and details, and monitoring of the quality of the work.
- Did not seem to have been aware of the consequence of inadequate supervision.
Building Approving Authority: RAJUK/Cantonment Board
- Unaware and indifferent to construction of a dangerously unsafe high-rise factory building built within its jurisdiction.
- Failed to stop unauthorized construction.
The Building Construction Act 1952
- Does not recognize construction and occupational safety as an important aspect of building construction. Main emphasis is given to planning and land use only.
Building Construction Regulations, 1996
- Failed to include BNBC 1993 recommendations for supervision of building design and construction.
- Vested design responsibility only to the architect for any structure and for residential buildings higher than four stories. An architect does not have the educational background and design capability to handle such responsibility.
- Engineering bodies, for failing to make the civil society aware of the danger that lies in the present construction practice.
- Corrupt and dishonest building officials, for allowing malpractice to continue.
- Construction supervisors/inspectors failure to sincerely supervise due to intimidation by mastans and influential mal-practitioners.
- Law enforcing agencies fail to safeguard honest officials.
Table-1 shows the list of actions, inactions and non-compliance issues with quality assurance and quality control requirements/principles which led to the failure of the Spectrum sweater factory.
The Committee feels that the aspects stated in the table point to a number of issues that should be debated nationally to develop an appropriate policy to implement and regulate Building Code Requirements for a safe and functional building.
All concerned organizations/Agencies should install appropriate Quality Assurance (QA) scheme within their set up to prevent similar failures as in Spectrum Sweater Factory. The parliament has enacted “Dhaka Metropolis Building Construction Rules, 2006” (DMBCR, 2006) on April 16, 2006. In the light of experience gained through Palashbari failure, it would be pertinent to examine, if such regulation can prevent such crisis. It had not been possible for the Committee to fully review the DMBCR, 2006 in light of the Palashbari incident.
Let's all seriously learn lessons from the failure of the 9-storied Spectrum sweater factory building. Achieving quality and safe infrastructures require commitment from the top levels of the democratic government, law enforcing Agencies, Owners/Investors first.
The Owner, in case of the important Spectrum factory building, instead of engaging an individual professional should have engaged one qualified registered architectural/structural consulting firm with good track record for planning, designing, preparing drawings, specifications, estimates of quantities & cost and brief tender documents, and for supervision of works; and one competent registered construction firm for constructing the building.
A proper contract defining the responsibilities of the First Party (Owner) and the Second Party (Consulting/Construction Firm) including the compensation package should have been signed and followed. Learned Societies such as IEB, Institute of Architects (IAB) and Institute of Planners Bangladesh (IPB) should provide facilities for prospective owners to choose qualified registered firm(s) with good track record.
The ISO 9001:2000 Quality management systems - Requirements gives the comprehensive steps to be followed for each stage of planning, designing and development. As an example the sample design and development stages activities of similar structures are given below:
Step-1 Planning of the activities: The Consultant's organization shall plan the different stages activities including those of the review, verification and validation of the design and development stages. The Consultant's organization shall manage the interfaces between different groups involved in the design to ensure effective communication and clear assignment of responsibility.
Step-2 Design brief/input: This will contain the Owner's requirements regarding functional and performance requirement, statutory or regulatory requirements for example, mandatory requirement of following the prevalent Building Regulations with Amendments (AMDs) if any, the Bangladesh National Building Code 1993 (BNBC 1993), design loading, material specifications, and other essential requirement for designing the building etc.
Step-3 Design output: The output of the design stage activities will be appropriately computed design and drawings, appropriate information for constructing the structure, acceptance criteria of the different components of works, and the characteristics of the finished structure or its components that are essential for safe and proper construction and use of the facilities. This design output will be in a form that enables review/verification against the design input and shall be approved prior to release.
Step-4 Design review: The review will be done to evaluate the ability of the results of design to meet Owner's requirement, and to identify any problems and propose necessary actions. All records of review should be properly documented and preserved.
Step-5 Design verification: The design & drawings and other documents should be verified whether it meets the requirement of design brief. Records of the results of verification and any necessary actions shall be documented properly and kept in record.
Step-6 Design validation: This stage activities will be performed to check the correctness of the input data, and to ensure that the resulting structure is capable of meeting the requirements for the specified requirement or intended use of the building for which It's designed. This validation will be completed prior to delivery of the design drawings and other documents or implementation. This shall be done by a professional of higher relevant experiences. Records of the results of validation and necessary actions shall be maintained.
Step-7 Control of design changes: The design changes shall be identified and records maintained. The changes shall be reviewed, verified and validated as appropriate, and approved before implementation. The review of design and design changes shall include evaluation of the effect of the changes on the constituent parts and documents already delivered. Records of the changes and any necessary actions shall be maintained.
Similarly, for the construction stages activities the supervision and quality control sampling and test requirements are to be developed and followed.
The lessons learned from the Spectrum sweater factory building failure strongly emphasizes the need for the implementation of Quality Management System in our organizations, and achieve quality assured structures and services for the building industry. This also requires to critically review and evaluate weakness in our present system of building planning, design and construction regulations, the need for training individuals at all levels of work and bringing commitment to it. Of course this needs commitment of all concerned including the top level of governance. Political will of the democratic Government is a must to achieve it.
BACE Bangladesh Association of Consulting Engineers
BGMEA Bangladesh Garments Manufacturers and Employers Association
BUET Bangladesh University of Engineering & Technology
DMBCR Dhaka Metropolis Building Construction Regulations
GoB Government of Bangladesh
ISO International Standards Organization
QA Quality Assurance
QMS Quality Management System
RAJUK Rajdhani Unnayan Kartripakhya
Acknowledgement is due, but not limited to, the following persons:
1. Dr. Sekender Ali, Head, Civil Engineering Department, BUET for all out assistance in this study.
2. Engr. Md. Nurul Amin, Development Constructions Limited, for arranging to unearth the failed foundation column that was completely covered by debris.
3. Various Newspaper/Media whose report and pictures have been used in the analysis of the event.
4. Commander, 14 Independent Engineers Brigade, Bangladesh Army, for supporting our visit during critical rescue operation and for providing valuable information on collapse and rescue.
5. The Institution of Engineers, Bangladesh for commissioning this study.
6. A large number of individuals and organizations who helped us with information
and suggestions. We render our sincere apologies for not including their names in this list.