Structural Safety Audit- Overview

A paper based on this blog was published in the journal 'The Bridge & Structural Engineer' Vol.54, No.3 September 2024 published by ING-IABSE. It is downloadable from the link below.

Article by Mr. Manoj Mittal - IABSE-Vol. 54 Vol. 3 Sept 2024.pdf

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Structural Safety Audit often called as Structural Audit is a buzz word particularly in India in view of aged and deteriorated buildings and other infrastructure assets. Its importance has further increased as we are witnessing series of structural failures. These partially or complete failures are not limited to non-engineered or old structures but recently built structures as well. India’s construction landscape is characterized by rapid urban growth, diverse infrastructure, and a significant share of aging and informal structures. Structural safety audits serve as a preventive mechanism to ensure that buildings and other structures meet safety standards, withstand environmental and usage stresses, and provide secure occupancy for the public. In the light of recent incidents of structural failures, including building collapses and bridge failures, the importance of robust structural audits has become paramount. In the following paras I have tried to examine the importance of structural safety audits within the Indian context, evaluate the existing framework for conducting these audits, review the methods employed, and analyze challenges faced. Furthermore, attempt has been made to suggest improvements that could make structural safety audits more effective in enhancing the safety and sustainability of India’s infrastructure. Structural safety audits provide a systematic approach to evaluating the condition of buildings & other infrastructure structures identifying potential risks and recommending remedial actions. Their importance is underscored by several factors unique to India:

• Preventing Structural Failures: Audits can help prevent catastrophic events like building collapses and infrastructure failures by identifying issues such as material degradation, construction or design defects, and excessive loads.

• Ensuring Compliance with Safety Codes: Structural audits assess adherence to established standards and codes such as the Indian Standards (IS) codes and the National Building Code (NBC), ensuring that buildings are constructed and maintained according to these standards and sound engineering practices.

• Enhancing Public Safety in Disaster-Prone Areas: India is vulnerable to natural disasters, including earthquakes, floods, and cyclones. Regular structural audits in disaster-prone zones ensure that buildings have adequate resilience against environmental stresses.

• Protecting Investment and Infrastructure Lifespan: Structural audits can extend the lifespan of buildings and infrastructure by identifying issues early and recommending timely maintenance or retrofitting.

• Legal and Regulatory Compliance: Structural safety audits can mitigate legal liabilities and fulfil mandatory compliance requirements, such as those outlined by the Real Estate Regulatory Authority (RERA) and local municipal regulations.

The structural safety audit framework in India is supported by various codes, standards, and authorities at national and local levels, providing guidelines for safe design/construction practices and regular maintenance. It is important to note here that Structural Audit is much different from Forensic structural engineering in terms of scope , methodology & objectives. Forensic Structural investigation primarily focused to finding the root cause of structural failure and fixing the responsibilities. However, many of the techniques, tests and methods are common to both.

Bureau of Indian Standards (BIS) is mandated to develop and revise and update  Indian Standards, including those for structural safety . However there also other bodies for specific domains like bridges. Adoption and implementation of these standards is done by individual departments, organisations, local & municipal bodies. While there are several states of art standards on design & construction aspects , standards for audit & retrofitting etc are either not available or not comprehensive . However, it is a work in progress in BIS.  Various relevant acts & policies are as under:

•  Real Estate Regulatory Authority (RERA) Act, 2016: RERA mandates structural standards in real estate, including a structural defects warranty, holding developers accountable for safety compliance.

• Indian Railways Act: Enforces safety standards for railway infrastructure, including regular audits of bridges and stations.

• State-Level Codes and Municipal By-Laws: Local authorities often have additional guidelines tailored to regional risks, such as flood-prone areas in Mumbai. They also make periodic structural audit mandatory for certain types of structures.

  
  

However, this list is in no way an exhaustive one and there may be many more acts relating structural safety audits.  Major role of Local Authorities/Govt Departments/Organizations can be summarized as under:

• Framing byelaws & policies for periodic Structural Audits

• issuance of Permits, Compliance & occupancy certificates

• Post-Disaster Assessment

• Coordination with Practicing Structural Auditors / Third party Audit

Major Challenges in the Regulatory Framework can be understood as under.

• Inconsistent Enforcement-As urban development is a state subject enforcement varies across regions, with urban areas more rigorous than rural areas. Byelaws and policies vary state to state. Even there are variations in local bodies within the state. Policies are also not consistent and effective in many states/bodies.

• Resource Constraints- Local authorities face shortages of skilled manpower and testing equipment, limiting audit frequency and depth. Usually, they do not have inhouse competence to do Audit .Most of the time they depend on Private structural engineering consultants/Auditors or IIT/NITs for Structural Audit reports. They have no system/mechanism to ensure that hired agency is competent. Lack of any central legislation and engineers act also makes it difficult.

• Public Awareness-There is a lack of awareness about the importance of audits, especially in areas not subject to recent structural incidents. Most of the times owners go for auditing only to ensure regulatory compliance. They are not sensitive to the importance of Structural safety Audit.

  
  

  

  
  

  Structural Audit needs comprehensive understanding of Structural engineering behavior, analysis, design, Provisions of Codes/standards, materials, construction practices, testing techniques, strengthening methodologies and investigative acumen. Structural Audit is performed by experienced competent structural engineers well versed in above areas. Service Sector department of BIS is developing a standard for covering service aspects of structural auditing. Structural safety audits employ various techniques to assess a building/structures’ condition, using both visual inspections and advanced diagnostic tools. Visual inspections are typically the first step in audits, where engineers assess physical signs of damage, such as cracks, corrosion, and water leakage. This stage is crucial for identifying obvious issues and guiding further non-destructive testing (NDT) procedures. It also involves checking and verifying various design drawings. Non-destructive Tests usually part of all structural Audits. They are used to get the data regarding residual strength of concrete, level of corrosion, to check cracks or quality of the materials used in the construction. There are various advanced tests are available for such investigation like Ultrasonic Pulse Velocity Test, Rebound Happer Test, Ground Penetrating Radar (GPR), Pull out test, Infrared Thermography, and various other laboratory tests. If requited Concrete Core test can also done. There are several BIS standards available for such tests.  In high-seismic and high-wind areas, auditors may simulate conditions to assess a structure’s resilience, often using computational modelling to evaluate earthquake or wind load resistance keeping in mind existing structural framing system, loads and available strength of the existing structural members. It is like doing an analysis and design of a new structure but with limitation of using existing framing and material properties. It will give fairly good idea about structural adequacy.  

Advanced Structural Health Monitoring (SHM) systems use embedded sensors to continuously monitor structural conditions, providing real-time data on stresses, deformations, and material degradation. Though costly, SHM systems offer critical insights, especially for infrastructure exposed to heavy loads or environmental stresses. It is a very promising upcoming area and data obtained can very effectively be used for structural safety audit. Now Artificial Intelligence & Machine learning techniques are also being used for real time Structural health Monitoring.

Despite established frameworks and methodologies, several challenges complicate structural safety audits across India. Major Challenges in Structural Safety Audits in India are discussed below-

• Historical Structures - Preserving heritage structures requires specialized techniques, complicating standard audits. It is not possible to do detailed reliable structural audit of such structures with commonly known techniques and methodologies.

• Old Public Infrastructure- Many Old government structures lack latest design specifications and they often do not meet latest safety provisions prescribed in standards and guidelines. Most of the time design drawings are also not available.  it poses great challenges while conducting audit.

• Skilled Professional Shortages – Competent & experienced Structural engineers well versed in auditing/retrofitting are in limited supply, particularly in rural areas. As mentioned earlier even if structural engineers/auditors are available in urban areas/metro cities it is very difficult to identify competent one. Quality of engineering graduates coming out of colleges, lack of engineer’s act, almost non-existent mentoring mechanism and low remuneration are primary reasons.

• Financial Limitations-Budget constraints prevent many municipalities/owners’/ organizations from conducting comprehensive structural audits.

• Owner Reluctance: Property owners are often unwilling to invest in audits due to potential repair /retrofitting costs and inconvenience it may cause to the users of the property. They often miss the larger picture. Most of the time they do it superficially just for compliance purposes. It hardly serves any purpose.

• Low Awareness of Standards: Many property owners lack knowledge of safety requirements, reducing their motivation to conduct audits.

• Enforcement Gaps: Implementation varies by region, and informal construction often bypasses safety codes. Corruption, vested interests, and unethical practices at every stage are the primary reasons for such gaps.

• Delayed Retrofitting: Procedural inefficiencies often delay needed retrofits if recommended by safety reports especially in older buildings.

• Seismic Zones and Flood-Prone Areas-Structures in high-risk zones require frequent audits but face logistical difficulties.

• Climatic Extremes - Monsoon rains and high temperatures accelerate wear and tear, necessitating more frequent assessments which owners usually wants to avoid. They indulge in superficial repair without any structural audit and expert advice on strengthening.

• Limited Access to SHM Systems - High costs and lack of awareness amongst engineering fraternity restrict SHM implementation even in high-profile structures.

• Data Gaps – Most of the time auditors do not get construction drawings of the project and it complicates the assessments of older structures. Many times, even if drawings are available, they do not match with the existing structures due to deviations during construction and additions/alterations later. Extracting such data by ferro scanning etc. is time consuming and costly. It is also not very accurate. This is the most common challenge faced by the structural auditors.

• Legal Notices/Litigations- Many times Structural Engineers doing audit are served with legal notices and dragged in litigation by affected parties. Structural Engineers must be careful on this aspect. It can be overcome by having proper contract agreement and drafting the report very carefully with disclaimers.

In view of the above discussions following recommendations for Improving Structural Safety Audits Practices can be made.

• Enhanced Public Awareness: Campaigns to educate building owners / residents and owners of other infrastructure on the importance of structural audits is needed. Professional Institutions/associations can also play a significant role in this regard.  

• Increased Funding and Resources: Government grants and funding could facilitate audits for high-risk and aging buildings. Government can come up with such a policy. It is a very tricky and difficult step, but government must consider this on priority.  

• Standardized Enforcement: Uniform enforcement across states and regions would ensure consistent safety practices. It is difficult in India as urban development is a state/local subject, but government can issue standards guidelines and Standard operating procedures(SOP) in the regard. States and local bodies can adopt them in their byelaws and statues.

• Adoption of Advanced Technologies: Increased use of SHM and predictive modelling could improve audit depth and reliability.

• Capacity Building- Structural Engineers must be trained for Structural Audit purposes by upgrading their knowledge. It can be done by some short term/part time courses by professional bodies in association with academic institutions.

• Codes/Standards- Development of codes and standards for structural Audit of diverse types of structures must be developed by BIS/IRC. These should be in simple language which can be easily understood by engineers. It will bring uniformity and  increase the compliance.

Structural safety audits are a vital component of India’s public safety and infrastructure resilience strategy. A robust framework, supported by advanced methods, regulatory compliance, and public engagement, can reduce the risk of structural failures and ensure that buildings are safe, sustainable, and resilient to environmental stresses. Addressing the current challenges through resource allocation, enforcement standardization, and technological adoption will significantly enhance the effectiveness of structural audits, thereby contributing to a safer built environment in India.

[ MANOJ MITTAL, NOIDA, November 7, 2024]

Acknowledgements- various standards, policy papers & internet sources.

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