When collecting core samples in cases of structural failure, it's crucial to follow specific guidelines to ensure accurate analysis and diagnosis of the failure. Here are some general guidelines:

1. Safety First:

Prioritize safety for yourself and others involved. Assess the stability of the structure before taking any samples. Wear appropriate personal protective equipment (PPE) and follow safety protocols.

2. Document the Site:

Take detailed photographs and notes of the site before taking any samples. Document the overall condition of the structure, the location of the failure, and any visible signs of distress.

3. Identify Failure Mode:

Understand the type of structural failure (e.g., shear failure, flexural failure, buckling). This information will guide the sampling strategy.

4. Strategic Sampling:

Plan your sampling locations strategically based on the suspected failure mechanism. For example, if there's a crack, sample from the crack location and extend the sampling to areas that show different degrees of distress.

5. Use Appropriate Tools:

Select the right tools for core sampling based on the material of the structure. For concrete, use a diamond-tipped core drill. For other materials, use tools suitable for the job.

6. Sample Size and Orientation:

Take core samples of sufficient size to capture the failure mechanism. Ensure that the orientation of the core samples is consistent and aligns with the suspected failure mode.

7. Depth of Sampling:

Sample deep enough to capture the full extent of the failure. If possible, sample beyond the visibly damaged area to analyze unaffected material.

8. Preservation of Samples:

Preserve the integrity of the samples. Handle them carefully, and store them in appropriate containers to prevent contamination or damage during transportation.

9. Labeling and Documentation:

Clearly label each core sample with information such as the location, depth, orientation, and any relevant observations. Document the sampling process thoroughly.

10. Transportation:

Transport the core samples to the laboratory promptly and under controlled conditions to prevent alterations in the material properties.

11. Laboratory Analysis:

Work with qualified professionals and laboratories for detailed analysis of the core samples, including material properties, composition, and any signs of deterioration.

12. Important to know:

Always consult with structural engineers, geotechnical experts, or other relevant professionals to ensure that the sampling process is appropriate for the specific circumstances of the structural failure.

Ovidiu Jianu Thank you for addressing my question but how to select the location and how many samples are required is still not cleared. And Most of the failure or disputed case need some strong evidence which can be presented Infront of legal authority so i highly appreciate if you suggest some specific guidelines or codal recommendation.

Shivang Jayswal Specific guidelines and recommendations may vary based on the type of structure and the nature of the failure. Generally, for location selection we need:

- Failure Zone Identification - Identify the zone or zones where the failure occurred or is suspected to have originated. This may involve visual inspections, structural analysis, and consultation with experts.

- Representative Sampling - Select locations that are representative of the failure mechanism.

- Focus on critical structural components or elements that are relevant to the failure.

- Consult with structural engineers, geotechnical experts, and other relevant professionals to determine the most appropriate locations for sampling based on the failure characteristics

The number of samples should be determined based on statistical considerations and the variability of the material or structure. In some cases, a statistical sampling approach may be appropriate. Consider any minimum or maximum sampling requirements specified by relevant standards, guidelines, or regulations. Some standards may provide specific recommendations for the number of samples based on the size and type of structure. Be aware of any legal requirements for evidence collection. Consult with legal experts to ensure that the sampling process and the number of samples meet the standards for admissibility in legal proceedings.

Clearly document the rationale for the number and locations of core samples. This documentation can be essential in legal proceedings to justify the representativeness of the sampling.

You can also consult standards and guidelines. Here are some:

- ASTM International : https://www.astm.org/

- ACI (American Concrete Institute) : https://www.concrete.org/

- CSI (Construction Specifications Institute) : https://www.csiresources.org/home

- Local Building Codes and Regulations (check in your country)

Ovidiu Jianu Can you please share the specific link(or DOI or Reference link) of that document rather than the link of full website. In structural engineering fraternity we all know the ASTM, ACI and CSI. But if some one is used to or regularly deal with this type of case can suggest the Specific Recommendation. As you know the specific ASTM or ACI or any other guidelines please share its like. As you have mentioned the failure zone but what basis it can be classified? based on failure, based on impact, based on which parameter????