Project Profile

Structural Investigation and Repair

What we offer is shown by what we do because actions speak a million words. FORSMITH was tasked with a difficult problem to solve, however, we are the people you want and need working for you because we solve problems that no one else can. A problem arose where a previous consultant had tried and failed to solve, resulting in the client calling the experts at solving problems – FORSMITH – and we were originally tasked with solving a water intrusion issue.

 

Problem

During investigation of a parking garage we identified residual issues in addition to the water intrusion issue. A total of 500 locations in the underground with cracks, including a concrete girder beam with major issues that had begun spalling. This damage was likely caused by overloading due to improper design and effects of water intrusion. Previous repairs to the beam and other cracks were readily evident. Additionally, we identified separation along a structural expansion joint, which, after investigation and in collaboration with our network, was determined to be caused by differential settling of the building.

 

Challenge

Water intrusion is difficult to design around, and so where the previous consultant had proceeded with an invasive method by excavating above the parking garage, creating noise, debris, clutter, and ultimately, complaints, FORSMITH decided to take a different approach which will result in the satisfaction from the client. The beam was the next problem to be solved. The challenge was how we can reinforce the beam after repairs of the concrete without requiring an unload of the structure. Aside from the beam being poorly designed, the beam’s steel reinforcement was not installed as per the structural drawings. Additionally, the third problem that required attention was the separation of the building’s expansion joint. This separation is likely caused by differential settling resulting in a shear failure of the joint. The challenge faced was how to increase the foundations bearing capacity – the soil? In all, FORSMITH was faced with challenges in which we would overcome with the many advanced technologies and personnel.

 

Solution

Our team and network worked together to analyze the issues and determined an optimal solution. In collaboration with our network of engineers, we proceeded with a method of blindside waterproofing using a Poly-Urethane Resin (PUR) gel injection from the underside of the concrete slab, in the parking garage. This method minimizes noise, clutter, and debris and is just one example of FORSMITH’s proactive innovation, ensuring longevity of the solution. FORSMITH was complimented on how smooth the process was and the best part is the problem was solved without complaints from residents.

 

For the beam, FORSMITH used a Ground-Penetrating Radar (GPR) – a non-destructive test method – to locate steel within the beam. Stirrups were missing and rebar was improperly located. This is just one example of how FORSMITH uses technology to our advantage, and we have many more toys. The corrosion potential of the steel reinforcement was also tested in accordance with ASTM C876-15 – Standard Test Method for Half-Cell Potentials of Uncoated Reinforcing Steel in Concrete. The test indicated nothing above normal, however, FORSMITH does all that is necessary to determine extents of the issue and ensure no further issues can arise after implementation of our solution. Based on the investigation and in collaboration with Brad Burnham, now our Senior Engineer, and others, we came up with a solution to reinforce the concrete beam. The reinforcement involved three steps and three separate reinforcement methods. Step 1 was chipping away compromised concrete and re-pouring, step 2 was an epoxy injection using a low viscosity structural epoxy, and step 3 was a Carbon Fiber Reinforcing Polymer (CFRP) design. The CFRP design used two strips of carbon fiber laminate for structural strengthening along the bottom of the beam and carbon fiber fabric for structural strengthening in locations of missing stirrups. Together, these three methods of reinforcement increase the beam’s structural capacity, in accordance with limit states design process. Regarding the building’s expansion joint, FORSMITH specified a micropile foundation reinforcement. Further reinforcement was also provided by widening one of the columns from top of footing to bottom of parking garage ceiling slab. Currently, monitoring of the displacement using a Linear Variable Differential Transformer (LVDT) is still ongoing – another example of the FORSMITH’s technology and the extents we go to ensure that the smooth implementation of an appropriate and long-lasting solution.