The Business of the Integrity of Structures
You may well enquire as to the meaning of the 'Business of the Integrity of Structures'. Why is this important? Why should we be concerned with this business?
Structures provide the means to achieve almost every endeavour of our Society: the security of our homes; the water we drink and the food we eat; our health, wealth and education; transport; communication; and industry all depend intimately on Structures.
Structures don't last for ever. Every structure ever built is subject to the Second Law of Thermodynamics, which states that: the entropy of isolated systems left to spontaneous evolution cannot decrease over time, as they always arrive at a state of thermodynamic equilibrium where the entropy is highest. For the purpose of this discussion, entropy can be defined as the ratio of: the energy of formation of a structure TO its structural integrity at any time.
Energy of formation cannot change once the structure has been built. The Second Law of Thermodynamics requires, then, that structural integrity will always reduce over time...unless energy is added to re-establish structural integrity. As our global environment changes, the frequency and intensity of environmental impacts on our Structures will increase significantly. The requirement for maintenance of Structural Integrity will become more and more pressing.
Our business is the assessment of Structural Integrity at a given time, and the engineering design of methods and procedures for restoration of Structural Integrity. The following discussion outlines the methods and procedures We undertake in the assessment and restoration of Structures.
What is meant by Structural Integrity?
The Integrity of a Structure is a measure of the capacity of the Structure to perform its intended functions safely and efficiently.
Structures provide a wide range of functions, including: supporting loads; protection from environmental events; enabling commercial and industrial operations; and environmental management and control.
Structural integrity requires that all structural elements are sufficiently strong to support all design loading patterns, and sufficiently rigid to prevent unacceptible deformations of the structure or its components.
Assessment of Structural Integrity
Determine the current usage of the Structure, its consequential design loading parameters, and relevant environmental interfaces.
Detailed requirements for structural performance are defined within engineering design codes. Identify the applicable design codes, and how they impact structural performance requirements.
Define the structural form in detail, including age and condition of the structure generally and of the individual structural elements, structural materials, the shapes of structural elements, and connections between elements comprising the global structure.
With the structural form defined, prepare 3D computer models of the Structure.
Consider also interacting adjacent structures, and identify common load paths and areas of structural inter-dependance.
Prepare a Consequence of Failure profile for the Structure and its components.
Using the collected data and the prepared 3D computer models, run a number of structural analyses under various scenarios. Analyses will typically be carried out using commercial FEA software combined with specific application design software.
Comparison of structural analysis results against structural performance requirements yields the Structural Integrity Assessment.
Causes and Consequences of loss of Structural Integrity
Damage to structures can be caused both by natural environmental effects and by anthropogenic (man-made) events.
Natural effects include seismic events, strong winds, flooding, fires, droughts, foundation subsidence and erosion, corrosion of steel elements, and sulfate reactions on concrete.
Anthropogenic events include collision and impact, unregulated modifications, vibrations from machinery and equipment, and re-purposing of Structures. All of these are due, directly or indirectly, to rapidly increasing demands from population growth.
Consequences of structural damage will range between low-impact and catastrophic. Structural expression of damage will range between local ductile failures to sudden catastrophic collapse.
Time frames for progression of structural damage are expressed as failure risk profiles.
Combining Failure Risk with Consequential Effects provides an effective decision tool in the Assessment and Repair of damaged structures.
Restoring the Integrity of a Structure
remove the cause of damage
constant maintenance to prevent damage
local repair or global replacement
maintain structure in operation during repair work
Changing Environment of Structures
Global climate change is expressing as increasingly severe environmental effects on Structures.
Storm events become more intense. Earthquakes increase in magnitude. Flooding events involve higher water levels and faster water flows.
As sea levels begin to rise, coastal infrastructure will be effected globally.
National and international design codes will have to be revised to adequately address increased loading patterns. Construction practices will need to adapt to meet increasing demands.
Resource availability will also begin to change, affecting capacity to maintain Structural Integrity.
By seeking, you will discover ( JS Bach )