Lean Construction Ireland Annual Book of Cases 2021 55 Case 14 Improve We held a Kaizen event with the team involved in the process of installing the panels. From our analysis using the Fishbone Diagram, we knew that time was being lost waiting for the correct configuration of the chains to lift the panels.We thus arrived at a solution based on the geometry of the lifting chains. To settle on the correct chain lengths we used the cosine rule.This states that the side‘c’of any triangle can be found with the following information: • The angle gamma ‘g ’ (must be the angle opposite side ‘c’) • Triangle side length ‘a’ • Triangle side length ‘b’ Figure 6. The Cosine Rule With this formula,we could establish the correct chain lengths for the unbalanced panels. In a lifting configuration, such as the one shown in Figure 1, there are four chains. If we set these two exterior chain lengths to be the same length as the span of the panel, we have created an equilateral triangle.The three angles within the triangle are all 60, as per the equilateral triangle rule. With these parameters set, we could factor in the two shorter, interior chain lengths within the lifting configuration, and we could now break the lifting configuration down into two further smaller obtuse triangles and designate these two smaller chain lengths as side ‘c’ in their respective triangles.Therefore, for a typical configuration (Figure 7 shows these angles and triangle sides) these would be: • a = wall span length • b = distance between lifting hooks as per shop drawings • g = 60° • c = formula in Figure 6 Having agreed that this formula calculated the correct chain lengths for the unbalanced panels, we created a spreadsheet where the correct chains lengths were calculated.To test our solution, we installed 8 unbalanced panels using the cosine rule formula.This resulted in an average installation time of 6 minutes and 48 seconds per panel.The floor-to-floor build cycle is 3 weeks, which gives sufficient time to plan and prepare for handling future unbalanced panels. Using the drawings from the precast panel supplier, we can make decisions based on their geometry. Figure 8. Isometric Plan of BlockA1 Level 01 (samples of potentially unbalanced panels circled in red) Some panels that appear to be unbalanced are in fact balanced.To find out which panel will require the additional work,we entered the dimensions into the spreadsheet we created for this purpose and arrived at the final number of unbalanced panels.As a result of this exercise, we arrived at a total of 96 unbalanced panels. The installation times achieved using the solution above saves approx. 12 minutes per unbalanced panel. In addition, by using the spreadsheet we could calculate that the actual number of unbalanced panels was averaging at 4 panels per floor for 8 floors across 3 blocks. Therefore, over 24 floors there would be approximately 96 actual unbalanced panels.The cost of installing pre-cast panels approximates to €275 per hour and includes the following elements: • Crane • Crane Operator • Installation Gang • Sisk Supervision Using our solution, time saved installing an unbalanced panel is approx. 20 hours, and, on that basis, the overall saving to the project is approximately €5,500. Lean Initiative Improvements & Impact Figure 7. Lifting Configuration with the Cosine Rule Built-In

RkJQdWJsaXNoZXIy MTIzMTIxMw==