THE CHALLENGE

The building had remained unapproved for more than six years because the completion certificate could not be issued for the planned property sale. Since the building was already completed, adding new columns was not a practical option. The rehabilitation therefore focused on increasing the load-bearing capacity of the existing columns. 

ENGINEERING SOLUTION

The strengthening methodology was developed around the existing columns, with the work carried out sequentially, one column at a time.

This controlled approach avoided simultaneously disturbing the existing load-bearing system and helped maintain the structural stability of the building throughout the rehabilitation process.

COLUMN STRENGTHENING DETAILS

• Existing Column: 300 × 200 mm

• Additional Anchorage: 16 mm epoxy-anchored reinforcement bars

• Anchoring: Bars installed by drilling into the existing column in both directions and fixing them with epoxy grout

• Stirrups: 10 mm reinforcement

• Reinforcement Spacing: 200 mm vertical and horizontal spacing

• Concrete Cover: 25 mm

• Strengthening Encasement: Approximately 75 mm around the existing column

• Concrete: 50 N/mm² (50 MPa) or higher high-strength self-compacting concrete with suitable admixtures

EXECUTION METHODOLOGY

1. Surface Preparation
Existing column surfaces were chipped and roughened using grinders to improve bonding with the strengthening system.

2. Epoxy-Anchored Reinforcement
16 mm reinforcement bars were drilled and epoxy-anchored into the existing column in both directions. Strengthening was executed one column at a time to maintain structural stability.

3. Reinforcement Cage
10 mm stirrups were installed around the existing column at 200 mm vertical and horizontal spacing, maintaining 25 mm concrete cover.

4. Shuttering & Concreting
Shuttering was installed around the existing column with a conical opening at the top. 50 MPa+ high-strength self-compacting concrete was poured through the opening, with controlled shutter vibration to assist consolidation and minimize voids.

5. Inspection & Verification
Shuttering was removed the following day and the completed encasement was inspected and found satisfactory. The strengthened columns were cured for 21 days, and 28-day concrete testing achieved more than 50 MPa.

ENGINEERING OUTCOME

The existing columns were successfully strengthened to increase their load-bearing capacity without adding new columns to the completed building.

KARTHIK'S INVOLVEMENT

Structural Engineering • Rehabilitation • Strengthening Execution • Site Monitoring • Quality Verification

THE CHALLENGE

Subsequent investigation identified sandy-clay soil conditions with a shallow groundwater level of approximately 1 m below the foundation.

Ground movement associated with the surrounding development affected the foundation soil, resulting in differential settlement toward the road side of the building. The other portion of the building remained comparatively stable.

A noticeable crack developed approximately through the middle of the building, extending through the wall and continuing down toward the foundation level, with the movement also reflected in the roof beam.

The challenge was to stabilize the soil beneath the existing building and strengthen the structure without dismantling the completed building.

ENGINEERING SOLUTION

A combined ground-improvement and structural-strengthening approach was adopted:

• Micro-Piling: 150 mm diameter micro-piles at approximately 600 mm intervals, extending to approximately 3 m depth from road level, to help restrain soil displacement beneath the foundation during surrounding development.

• Injection Grouting: Mechanically pumped epoxy-based injection grouting was carried out from the foundation level to approximately 1 m below foundation level to provide a stable soil base beneath the foundation. Injection points were arranged at approximately 1 m intervals in both directions across the building area, including the floor area.

• Structural Strengthening: Existing columns and beams were strengthened to improve their ability to withstand the effects of foundation movement and settlement.

MONITORING & OUTCOME

After the rehabilitation works, the existing wall cracks were repaired and the building was monitored monthly for approximately 1.5 years.

During the monitoring period, no further evidence of significant crack development or progressive structural movement was observed.

The major construction activity across the road, including deep excavation and piling, subsequently progressed to completion, while the rehabilitated building remained stable.

KARTHIK'S INVOLVEMENT

Structural Rehabilitation • Ground Stabilization • Micro-Piling • Injection Grouting • Structural Strengthening • Site Execution & Monitoring