Summary of Structure Adequacy Analysis

 As per the analysis for gravity loading & earthquake loading the structure is found not safe as per the current load condition.

  During visual inspection various structure defects such as concrete spalling, reinforcement exposed, cracks was found at the several localized locations. Hence it needs to be repair as per repair suggested.

Repair Method:

1.  All the defected area need to be repair as per patch Repair A as suggested in report.

2. Once the patch repair work is completed then the member need to be strengthen by means of low vicious injection grouting as per Repair B.

3. The rust from the steel members need to be remove and anti rust paint need to be apply as per Repair C.

4. It was suggested to remove first floor flooring and apply PU based water proofing or any other chemical proof layer on mother concrete and then refix the acid proof tiles over it. The grove or joint of tiles need to be fixed properly.

Note:- All these repair are suitable for a duration of 5 to 7 years only. Retrofit of the ETP for a long duration will not recommended dismantle and recast will be more suitable for long life.

1. Introduction:

1. Site

The existing ETP structure at xxxxxxxxxx  has requested to M/s OB DEVELOPERS (STRUCTURAL AUDIT AGENCY) for Health Assessment of superstructure through conditions survey using Non-destructive testing. This report pertains to the stated safety appraisal, health assessments. Objectives of the investigation and survey, general methodology and test procedures, etc. are given followed by details of the observations recorded at site and results of in-situ and laboratory tests.

1.2 Evaluation of the Structure

In order to assess the condition of the RCC structure, a thorough evaluation was performed. The testing consisted of:

• A visual inspection of the exterior exposed elements to determine if there were any obvious signs of distress, deflection or deterioration in the structure.

• A thorough inspection of the structure to determine the condition of the structure. This is essential as we found that the structure can appear to be in a very good condition from outside, but could be suffering from extreme structural distress from inside.

• Selective concrete removal to examine the condition of the underlying reinforcing steel.

• Materials testing to determine concrete compressive strength, cover depth.

1.3. Objectives of the overall investigation:

The overall objective of the investigation carried out for the structure is to obtain an up to date account of the health condition of the structure so that appropriate repair measures can be taken up to make up for the damages sustained. Keeping this in view the basic objectives of the investigation formulated are as given below.

1. To assess the existing condition of the structural elements.

2. To determine the extent of damages in the structure, so as to undertake suitable remedial measures for rehabilitation of the structure.

1.4. Planning of Investigation and Methodology

1.4.1 Walk over survey:

First and foremost activity in a condition survey and structural investigation, especially in distressed superstructure, is a walk over survey or systematic visual inspection so as to gather readily available information about the structure in question. Further, careful visual observation of typical crack pattern and the nature of the spalling can furnish valuable information regarding the distresses. This in turn provides an idea about the degree of damage encountered in the concrete and hence the extent of repair required. A systematic visual observation has been recorded in this investigation and the findings are presented in later part of this report.

1.4.2 Selection of tests:

Tests are selected on the basis of the requirements of the overall objectives of the investigation and the observations made during a quick walk over survey. In this investigation, following in-situ and laboratory tests were considered necessary for achieving the overall objectives stated earlier for the structure. Various Test were Conducted for the evaluation of the Structure: 

The various Non-Destructive Tests proposed to be carried out for condition survey of the structure are listed below:

1. Ultrasonic Pulse Velocity Testas per IS: 13311 (Part-1)-1992 for ascertaining the quality of concrete, soundness and density of concrete.
2. Rebound Hammer Test:  For determining the estimated compressive strength of concrete and uniformity of concrete in terms of surface hardness as per IS 13311 (Part-2)-1992.
3. Half Cell Potential Testas per ASTM C876-1991 for assessing the percentage risk of corrosion in reinforcement. Measuring the half-cell / surface potentials at selected locations on RCC members of the structures covered under the study to understand the extent of reinforcement corrosion. (Risk of corrosion of steel).

4. Carbonation Test as per BS EN: 14630 Measurement of carbonation depth by phenolphthalein spray test at selected locations on RCC members of the structures covered under the study to see the depth of carbonation.

5. pH Test: The phenolphthalein test method is based on a new British standard, BS Standard BS EN 14630

6.  Cover Meter Test as per is 456:2000 to measure clear cover of the structure members.

7.   Core Cutting: IS: 516, concrete extraction for exact in-situ compressive strength evaluation of concrete, grade and fck value of concrete.

1.5 Sample and Site Data Collection:-

The eight instruments i.e. Ultrasonic Pulse velocity meter, Rebound Hammer &, Half Cell Potential Test, Cover Meter, pH , core cutting ,Crack Pattern test & Carbonation test were used to collect the data from the structure sample as well as through the surface test locations were selected after visual survey and data was collected from below mentioned test locations in the structure. As per surface condition required numbers of tests on different concrete surface have been decided to get the overall idea of concrete quality.