The Retrofit Approach – Part 2/2

Improve the strength of the structure with ease
In-order to strengthen the structure, first it is important to determine the efficacy of the structure by consulting with a good structural engineer and going through a series of tests including physical inspection of the structure. For detailed understand, please go through The Retrofit Approach – Part 1. The above linked article provides details on the different types of retrofitting involved. In the present article, we will help make understand how we can minimize the demeriting factors in the different types of retrofitting and thereby increase the efficiency of the system.

Inspection & Status:
For aged structures, we find the present load bearing capacity of the structural members by assessing the depreciation. The life of a structure depends on various parameters including type of structure & design, external weather & seismic conditions, property & quality of structure material used, creep behavior in concrete, quality of construction method, etc. In addition, during a severe earthquake, the existing structure is likely to undergo inelastic deformation and depending on the ductility and energy absorption capacity to avoid collapse. Structures designed for gravity loading only needs to be strengthened to improve structure performance and efficiency.
On determining the present load bearing capacity of the existing structure, one or more of the following strengthening methods may be used if a deficiency is found in any of the structural members. There are two types of techniques, namely Global Techniques and Local Techniques.

Methods - Local Techniques of Strengthening:

 

Based on the above techniques, there are merits and demerits for each of the system. The demerits cannot be removed completely, but the effect of the same can be contained to certain extent. 

Demerit Factors in the different types of strengthening and how it can be minimized:
1.      Reduce the number of puncturing holes made in the existing concrete:

• Scan the existing concrete before drilling
• Scanning can be done through Ferro Detection Scanners like PS 300 & PS 1000

2.      Reduce the vibration effect on the concrete at the time of drilling

• Choose the right drilling machine with optimum hammering method
• Hilti’s wide portfolio of drilling machines based on the diameter & depth of hole to be drilled, helps you provide the right amount of vibration and reduce any further damage.
• SDS Plus drilling machine & SDS Max drilling machine with Active Vibration Reduction, DRS-Y for dust removal.

3.      Stress in existing concrete created by the additional member

• Use the right Chemical/ Mechanical anchor
• Hilti’s wide portfolio of Anchors can be chosen to the right application, which reduces the stress area in the existing member.

4.      The newly added rebar/ anchor to be installed as per design procedures

• Use effective and proper installation method – SAFESET
• Even though the design is done as per requirements, executing the same by ensuring proper cleaning methods and providing the required torque to the anchor remains on manual basis as per site conditions. Hilti offers you solutions such as:-

a) Hollow Drill Bit with Vacuum Cleaner for complete dust removal at the time of drilling
b) SAFESET Anchors (HIT-Z + HY 200R), which can be installed without cleaning of the hole
c) SIW-6-AT torquing machine, which can torque the anchor nut to the required torque as per the anchor diameter  

5.      Compiled report of the application for further inspection.

• Stage-wise documentation including photos, from the start to end using software applications
• Hilti Documentation Manager is an ease of use software which can run along in all platforms and the present stage of application can be documented at every instance of time.

6.      Steel needs protection against corrosion

• Use special steel coating techniques which can limit the corrosion
• Further details on Hilti Steel Coating will be shared upon launch of the same by end of 2020

7.      The time taken for the completion of the strengthening project.

• Use technologies which are cost effective and provides a faster solution
• Using cordless tools, reduced embedment depth of anchors/ rebar, saving time at the time of installation, all these parameters helps further in completing the project faster and effective. 

By reducing the impact of the demerit factors on the strengthening technique used, we can improve the strength of the structure for a longer period.
Hilti understands the existing gaps & we have therefore combined our principles with our ability to produce the best quality products and innovation to close these gaps. We have worked to provide solutions to any challenge that arises at a construction site and develop a customized solution just for you. The constraints that we face when undergoing a structural retrofitting work, can be minimized using HILTI Complete Solution.
Kindly let us know the hindrance or struggle in the retrofitting approach that you are currently working upon, and we are there to provide you the right solution. Please drop down these queries and your valuable comments in the trailing section. 

The complete solution kit will be covered in the webinar which is scheduled on 26th March 2020.

Click here to register for the Webinar "FASTER AND EFFICIENT WAYS OF RETROFITTING OF STRUCTURES"