Structural Audit

Structural Audit

Structural Audit Process

01. Preliminary Survey

02. Visual Inspection

03. Conducting NDT

04. Evaluating the data

05. Submission of Report

Why Structural Audit Require?

  • To Enhance the overall lifecycle of the building , its components need to be periodically examined so that there is no danger to its inhabitants.
  • A Structural Audit of building structure should undertake as follows:
    ▪️ For Buildings aged between 15 to 30 years old, the statutory requirement is to conduct a structural audit once in a 5 years.
    ▪️ For Buildings aged more than 30 years, structural audit must be conducted once every 3 years.
  • For Insurance
  • For Bank-Mortgage
  • For Valuation
  • Structure Showing Distress
  • Proposed Addition, Alterations Extensions in building / structure
  • For Damage assessment due to earthquake, fire, blast, vibration, corrosion etc.

Stages Of Structural Audit

Visual Inspection

Visual inspection is meant to quick scan to a building structure for distress.

Non destructive testing

Overall idea of conducting these test are to find out a Soundness of building structure.

Analysis of Audit Report

During this stage, an engineer categorized the damages or distresses into various types to decide the repair requirement and to access the right repair methodology.

Visual Inspection

Visual Inspection provides a valuable information to an experienced engineer about structural serviceability, its workmanship, quality of material and material deterioration mechanism. Engineers marks a distress on a layout plan from actual site to diagnosis the problem and quantifying the items required for repair work. It is always necessary to carry a flash camera during such visual inspections to photograph a distressed in building and its member.

List of Non Destructive Tests

UPV Test
Rebound Hammer Test
Half Cell Potential Test
Carbonation Test
Collecting Core For Core Cutting Test
Collecting Sample For Chemical Test
Cover Meter Test

01. UPV Test

Methodology:
  • Grease is applied on the test surfaces
  • The probes are pressed on the surface of the structural element to remove air gaps
  • Distance between the two probes is noted
  • Read time taken for the ultrasonic pulse from the instrument
  • Calculate Velocity = distance / time
Equipment Used:
  • Electric Pulse Generator
  • Transducer: One Pair
  • Amplifier
  • Electronic Timing Device

02. Rebound Hammer Test

Methodology:
  • The concrete surface is cleaned properly
  • The hammer is pressed against the concrete Surface and released
  • Six readings are taken and an average is taken
  • Correlate the average with the compressive Strength
Equipment Used:
  • Rebound Hammer

03. Half Cell Potential Test

Methodology:
  • Identify test location & drill a hole in the concrete to reach the reinforcement
  • Establish electric contact with the reinforcement
  • Place the half cell at various locations on the concrete surface & measure voltage in the voltmeter
  • Correlate the obtained voltages to probability of corrosion as per ASTM standard
Equipment Used:
  • Half Cell Potential Kit

04. Carbonation Test

Methodology:
  • Identify test location & drill a hole in the concrete to reach the reinforcement.
  • Inject chemical & insert steel rod
  • The colour change determines till what depth carbonation has taken place
Equipment Used:
  • Carbonation Measurement Kit

05. Concrete Core Test

Methodology:
  • Cores are taken using special diamond cutters of 75 mm, 100 mm or 150 mm diameter. Locations are selected to avoid steel so as to minimize the damage to the structure. 
  • The edges of the core are smoothened using grinding and cutting wheels and epoxy mortar is applied on both sides for capping. The core samples are immersed in water for 48 hours. The cores are weighed before and after immersion.
  • The cores are then subjected to compression forces on compression testing machine. The breaking point is observed
Equipment Used:
  • Core cutter
  • Core compression testing machine

06. Chemical Test

Methodology:
  • The chemical tests are conducted on powdered concrete sample collected from the site
  • The powdered samples are tested in the lab using test kits from reputed manufacturers
  • The obtained results are correlated with the permissible limits given by IS 456: 2000 code and reported
Equipment Used:
  • pH Testing Kit
  • Chloride Testing Kit
  • Sulphide Testing Kit

07. Cover Meter Test

Methodology:
  • A small, portable, and handy instrument which is known as profo-meter or rebar locator, is used in this test.
Equipment Used:
  • Profo-meter

Analysis of Structural Audit Report

This stage involves preparation of documents and grouping of the structural member. For example Beam crack, column crack, slab crack, floor damage, leakages from external wall, dampness in wall, leakages through beams and slab, dampness in slab, leakages from top slab etc. Analyzing the all the available data proper repair technique can be recommended.

Based on the preliminary inspection and visual inspection carried at site, as well as NDT performed an engineer made an observations and gives his best conclusions and recommendations to strengthening the existing structure or to existing structure should evacuate and demolish if necessary.

Following points to be prepared in this stage which completes a Structural Audit Report:
  • Description of building structure
  • Principles
  • Observations
  • Layout plans
  • Distressed mapping plans
  • Instrumentations
  • Non-destructive layout
  • Non-destructive test exhibits
  • Result and discussions
  • Summary
  • Conclusions
  • Recommendations
  • Bill of quantities
  • Exhibits