The+Role+of+Computers+&+Information+Technology+in+Building+Failures

The Role of Computers & Information Technology in Building Failures //Saratu Terreno, PE, AIA, Degree ??? Author Affiliation 2012 // toc
 * December 2015 **

Introduction
The use of computers and Information Technology in the Architecture, Engineering, Construction and Operations (AEC/O) industry has gone a long way in augmenting human capabilities. Numerous advantages have been recorded and proposed in the implementation of computer programs during the construction and operations processes, with new methods advancing in recent times towards the investigation of building failures. However, some of the failures in building performance have been caused by errors in computer programming and analysis. This paper explores the positive and negative aspects of the use of computers in structural functions. An overview of the use of computer programs in structural design, operations and forensic analysis is given, followed by a sampling of case studies illustrating failures caused by computer error and those that could have been prevented through the use of enhanced computing capabilities and concepts. The emerging field of Forensic Information Modeling is also examined, with examples of work done in this area analyzed in two case studies. The paper concludes by extracting lessons learned and best practices as prescribed by scholars on how to maximize the opportunities provided and value inherent in the implementation of computing technology in the AEC/O industry.

=Overview of Computer programs in AEC/O=

Predictive Functions: Analysis and Simulation
Reyes (2005), in reviewing the role of computers in structural engineering design and analysis, described the main functions as comprising modeling, simulation, validation and optimization of structural systems. 58 types of software falling into these categories were analyzed in themes comprising the extensive range of modeling capabilities, types of structures/members, functions, material capabilities and features. This illustrates the wide variety available in the industry for design, structural optimization and structural health monitoring. A sampling of two concepts in structural analysis and simulation are described below as examples of the application of computational capabilities currently applied in structural analysis and simulation; though numerous other concepts and methods exist.

Analysis: Structural Optimization
Mueller et al. (2012) described structural optimization as the development of design options for optimal structural design. A number of software options were discussed, noting their capabilities and main advantage that they afforded design, which was speed. Table 1 below describes the capabilities and features of the software that were analyzed:

TABLE HERE

Simulation: Computational Fluid Dynamics
Computational Fluid Dynamics techniques have been described as a more cost-effective and time-saving method for prediction and testing of the wind behavior of tall buildings Mendis et al. (2014). The flow behavior of wind is applied to a virtual model thus serve to advance human imagination based on established principles of fluid flow. CFD has been applied in recent times in the design of tall structures such as the Burj Khalifa in Dubai, UAE which currently stands as the world’s tallest structure (Baker et al., 2009). The insufficiency of existing codes in varying contexts and countries of the world was highlighted by Mendis et al. (2014) as a limitation which can be addressed by the application of CFD technologies in the design of uniquely tall buildings. A main point to note is that the effects of the surrounding urban environment should be taken into consideration in the analysis.

Barriers faced in the wide adoption of software were described by Mueller et al. (2012) as the need for the development of suitable/appropriate software. There also lies a need for increased awareness of the justification of software expenses through studies proving adequate Returns on Investment (ROI), and the proving the validity of the software. Existing benchmarks would also need to be expanded from a predominant safety focus to one including cost. Other challenges were named to include inconsistent / incomplete criteria for structural optimization techniques.

Monitoring Functions: Embedded Systems for Structural Health Monitoring (SHM)
Charles & Worden (2007) described SHM as the deployment of a “damage-identification strategy” through non-destructive techniques. The main function of SHM comprises monitoring and proactive notification of structural deviation from expected behavior. This would serve to enhance safety for the users of the structure, and allow for savings in operations due to the proactive ‘condition monitoring’ and notification features. Available tools such as sensors perform the monitoring function, transmitting information to Fault Detection and Diagnostics (FDD) software, which in analyzes the data using statistical process control, stores it and issues important notifications. Thus an informed picture of the current ‘structural health’ of a structure is available in real-time, which increases the efficiency of its management. However, rapid condition screening is available for determination of structural health and damage prognosis in extreme events such as earthquakes.

Challenges to effective SHM comprise the ability to capture system response in a timely manner; and the practicality of accurate capture. In designing the system, there exists a dearth of comprehensive historical information from past failures to enable broad and informed feature selection and definition of damage identification criteria. The health of the sensor hardware and networks would need to also be proactively monitored, and the justifications provided for their associated costs and benefits to owners and regulatory agencies.

Wireless sensors are ‘autonomous data acquisition nodes’ with enhanced capabilities embedded within conventional structural sensors such as accelerometers and inclinometers Lynch & Loh (2006). The main advantage of wireless sensors is the advanced computational capabilities they offer for real-time, hardware-free data processing. Lynch & Loh (2006) noted that wireless sensors are significantly less expensive to install than their wired options. Limitations of wireless sensor technology include the need for more advanced system architectures and operation modes. Other challenges include the issue of power consumption and battery life. Passive sensors merely measure data, whilst active ones can physically respond to conditions based on established parameters. Failure detection can be either localized to a component or system-wide – referred to as ‘global-based’ damage detection. However, a major limitation is that damage may be localized and not significantly alter the performance of the system as a whole until it is probably too late (Farrar et al., 1999).

Giorgiutiu & Bao (2004) described the combination of Embedded-Ultrasonics Structural Radar (EUSR) for real-time monitoring of thin-wall structures as a viable alternative to the Non-Destructive Evaluation (NDE) option. Another advantage of this system is the comparatively lessened weight and cost of the technology.

Failures Caused by computer error – human errors in computing

 * 1) **Hartford Civic Center (Jan. 18, 1978):** although design and construction concern were brought to the attention of the engineers of this structure, they were repeatedly dismissed owing to a blind reliance on the computer analysis model. The assumptions entered into this had been deficient, which led to the computer model’s error. More details can be found here: https://failures.wikispaces.com/Hartford+Civic+Center+%28Johnson%29
 * 2) **Kemper Arena (June 4, 1979):** one of the main causes of its roof collapse has been attributed to a computer-related design deficiency. The engineers failed to independently validate the results of the computer analysis, which as in the case above, had improper input parameters. It is fully discussed in the article related to this link: https://failures.wikispaces.com/Kemper+Arena%2C+Kansas+City%2C+Missouri

Failures that could have been prevented - extension of codes in predictive design

 * 1) **Ronan Point Apartment Tower (May 16, 1968):** being an innovative structure for its time, the design of the Ronan Point Apartments stretched the limits of the existing building codes of its time (link to the document here: https://failures.wikispaces.com/Ronan+Point . Thus no one envisioned the possibilities of the scenario which initiated a chain reaction and exposed numerous design and construction flaws. Lessons learned were put into action by initiating amendments to the building codes. However, in modern times the advancement of computer capabilities now offers the opportunity to simulate situations and virtually test the effects of a large number of variant parameters that could act on a building at any time during its lifecycle. Structures such as the Burj Khalifa, which is currently the tallest in the world were subjected to numerous testing conditions such as Computational Fluid Dynamics to simulate and test wind loads on the various proposed shapes. Thus structural optimization was achieved by choosing the most favorable options such as shape, materials and envelope structure (CITE).
 * 2) **London Millenium Bridge (June, 2000):** The increasing sophistication of modern structural design is an aspect purported to bear potential for design optimization. In the case of the London Millenium Bridge failure the designers had adhered to every code and protocol, yet were unable to foresee the unprecedented event of its overloading on the day of its opening (found here: https://failures.wikispaces.com/Millennium+Bridge+Performance+Issues ). The structural implications of over 100,000 people crossing it, 2,000 at a time became overwhelming, with lateral movement causing swaying of the bridge. Advances in computer simulation and modeling optimization have thus enabled present structural designs to envision situations and outcomes well beyond building codes.

Failures that could have been prevented - collaboration and information sharing

 * 1) **C.W. Post College Auditorium (January 21, 1978):** a major focus of the discussion of the investigative panel looking into the collapse of the 170 ft span shallow dome of this auditorium was collaboration. The lack of this became glaring during the investigation, exposing huge gaps that had been overlooked by the design team in the development of this long-span structure. In an analysis of the collapse (https://failures.wikispaces.com/C.+W.+Post+College+Auditorium+Collapse ), the author noted that recent advances in more collaborative project delivery methods and technological interoperability can go a long way in solving issues of disunion in design. The team approach can be optimized now with much less strain on project members because of the easy availability of computing networks and virtual design.

Failures that can be prevented: Real-Time Structural Health Monitoring
The opportunity to proactively monitor a building’s performance in real-time has been enhanced following the development of convenient wireless sensor technology. The “Overview of Temporary Structure Failures in Construction” (found here: https://failures.wikispaces.com/Overview+of+Temporary+Structures+Failures+in+Construction ) provides a comprehensive description of the variety of failures to which temporary structures are susceptible. Numerous case studies were cited by theme – temporary performance stages, formwork, scaffolding etc, with the trends and patterns of the failure incidents mapped. The conclusion of this highlighted the dearth in regulations for temporary structures, or their insufficiencies thereof. Real-Time monitoring of these structures was proposed as a more proactive and overarching solution to the problem. The concept of Cyber-Physical Systems (CPS) was introduced, which proposes the embedment of computers and networks with bi-directional communication enabling feedback loops of information and real-time analysis of the safety of a structure.

Investigative use of computing technology: Forensic Modeling
Forensic Information Modeling (FIM) has been described as the maximization of the use of information models and semantic databases for analysis and trending of patterns in failure investigations Lau et al. (2014). The concept was first developed by Thornton Tomasetti for more heightened capabilities in the investigation of the failure of the I-35 W Bridge in Minnesota. A two-pronged benefit of FIM comprises the augmentation of human abilities in “pre-process filtration” of information, and the advantage of simplified visual “post-process communication” to a broad composition of audiences. The main challenge of traditional forensic investigation is the vastness and complexity of data, and the variance of analytical methodology and conclusions. Even though computers solve this to some extent, as Reyes (2005) stated, that the quality of a computer’s analysis is only as good as the information put into it.


 * 1) ** World Trade Center Building 5: ** LaMalva et al. (2009) described how a specialist team from the ASCE and Federal Emergency Management Agency utilized computer analysis and simulation techniques in the investigation of the World Trade Center Building 5 collapse. They used a Fire Dynamics Simulator (FDS) in a Computational Fluid Dynamics (CFD) model to further understand the workings of “fire-driven fluid flow”. This enabled them to estimate the Peak Heat Release Rate (Peak HRR) per unit of floor area, and thus values for the effective heat of combustion. CFAST was also used to simulate the fuel-controlled fire. ABAQUS was chosen as the Finite Element Modeling (FEM) software to analyze the shear connection assembly of the four critical structural bays related to the collapse. The outcome of this analysis provided further information on temperature-dependent stress-strain curves for the steel, true plastic strain, a thermal model illustrating heat transfer behavior and its accompanying temperature distribution on the steel. The overall thermal stress simulation was developed, with failure criteria for existing connections.
 * 2) ** World Trade Center Building 7: ** the use of FEM software was also applied in the investigation of the collapse of this tower. Engineers from the National Institute of Standards and Technology (NIST) performed virtual tests on the computer model, checking the gravity loads, debris impact damage from the WTC building 1 and effects of high temperatures. More information can be found at this link: http://failures.wikispaces.com/World+Trade+Center+-+WTC+7
 * 3) ** I-35 W Bridge, Minnesota ** : Brando et al. (2013) utilized 3-D modeling to create a visual model of the I-35W Bridge in Minnesota, and embedded semantic information within this detailing the history of the structure. Relevant historical information in this respect comprised design and maintenance data, and included retrofit details. The linear behavior of the bridge was analyzed using an SAP mode, ABAQUS was employed for the evaluation of the post-bucking capacity of members and the combined outcomes were integrated within an LS-DYNA model for a holistic analysis of the origin of its failure. Following conclusion of analysis, 3-D animation was developed for enhanced communication of technical issues to the client.

= Discussion=
 * 1. Engineers Responsibility**

Reyes (2005), in analyzing the effects of computer-enhanced capabilities on the practice of structural engineering highlighted the positive and negative sides of it. He noted that although computers enhanced the capabilities of designers and helped to improve collaboration and communication, visualization and design accuracy, the professional and legal responsibilities of engineers were in no way diminished in light of trending technologies. Reyes (2005) highlighted the increasing neglect of fundamental principles, conceptualization and think-through processes owing to the over-reliance on computers. Efforts at result validation have greatly decreased, further noting that the analytical capabilities of a computer are “only as good as the information put in.” another major challenge to professional ethics was owed to the over-simplicity of computer programs which afforded computer-savvy non-professionals the opportunity to design.


 * 2. The advantages of simulation in design and investigation**

The use of simulation in design is described by Baker et al. (2009) as “a successful collaboration” between wind engineering, structural system requirements and architectural aesthetics. Modeling and simulation have proven their positive potential in augmenting human capabilities from the conception of a structure through its maintenance and even to the unpleasant task of investigating its failure. As highlighted by Brando et al. (2013), its dual advantage of enhanced analysis and extended communicative ability makes the job of the structural engineer easier and more effective. It is thus important to continue to advance the adoption, implementation and development of computational technologies in the AEC/O industry, taking care not to neglect the fundamental principles and legal responsibilities of Engineering.


 * 3. The importance of recording and sharing past failure cases**

Charles & Worden (2007) noted the dearth of comprehensive historical information from past failures which in turn constrains the informed and holistic programming of SHM systems. There is therefore a need to record lessons learned from past failures for the overall benefit of the engineering profession, which would serve to prevent future failures. Trends, patterns and even unusual clues can be incorporated into computer programs in the development of broader and more significant algorithmic structures to enhance structural health monitoring and failure detection.

**Conclusions**

The role of computing in structural engineering was examined in this paper. A sampling of computational capabilities and their advantages and challenges were described with the aid of case studies according to three main themes. Failures that were caused by computing errors, those that could have been prevented and others which have been successfully investigated with the aid of software technologies were evaluated. It was found that although computing technologies are an important part of structural engineering, the legal and professional responsibilities of an engineer are in no way diluted by the technologies. The development and enhancement of computing technologies were also found to be highly dependent on the preservation and open sharing of historical information from past failures for well-rounded success. Human collaboration and information sharing during projects was also found to be a salient part of successful design and construction.

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