Structural strengthening using Steel Plate and Bolts

Structural assessment may be done because there are changes in its resistance due to structural deterioration such as corrosion, fatigue, and structural damage by accidental actions. It also can be initiated when there will be a change in loading (e.g. increased live load) or an extension of the design of working life due to changes in the function of a building. Generally, the structural assessment is a process to determine the reliability of the existing structure to carry current and future loads and to fulfill its task for a given time [1] Ruker et al (2006). The reliability of the existing structure is obtained from the reliability of the structural elements (i.e foundations, beams, columns, and slabs) to resist internal forces. When the results of the structural assessment show that some structural elements have deficiencies in axial, shear, and flexure capacity, a strengthening action may be required.

One of the methods to improve the capacity of the elements of the reinforced concrete structural frame uses external reinforcement of steel plates and bolts. The methods have been studied experimentally and analysis. Application of steel plates and bolts to the shear strengthening of reinforced concrete beams has been tested by [2] Sudarsana et. al (2019) to investigate the shape of steel plates namely L-shape and U-shape, It shows that both steel shapes can increase the shear capacity of the beams. the U-shape gave a better performance than the L-shape. Using the steel plate thickness of 1mm can improve shear capacity at cracking loads and ultimate loads up to 52,6% and 6,57% of the original beams, respectively. Numerical analysis was done by [3] Sudarsana et.al (2020) also shown the external reinforcement using steel plates and bolts gave an improvement in structural element capacities.

The strengthening method using steel plates and bolts has been applied to existing structures, for example, SPS Building Jimbaran Bali. After the structural assessment has been done due to low concrete strength and changing the service loads, some of the structural elements have strength deficiencies. The following figures show the strengthening applications in the building [4] (Sudarsana et.al, 2020). The performance of the strengthening was evaluated for the intended service load of 1000 kg/m2 on the slab using a direct loading method. The results of the direct loading test show that all monitored beams and slabs have acceptable deflections indicated that those members have enough strength and safety.

(a) Strengthing of the beams for shear and flexure at beam ends.

(b) Strengthening of the column for axial, shear and flexure using steel angle and plates

References

[1] W. Rücker, F. Hille, R. Rohrmann, Guideline for the Assessment of Existing Structures, Federal Institute of Materials Research and Testing (BAM) Division VII.2 Buildings and Structures, Berlin, 2006

[2] I K. Sudarsana, I P.C. Sajana, and IG.O. Suputra, Application of Bolted Steel Plates to Shear Strengthening of RC Beams, MATEC Web of Conference 276 (2019), https://doi.org/10.1051/matecconf /20192760 1002. 

[3] I K. Sudarsana, I.B.R. Widiarsa, IG.G.Wiryadi, and IP.C. Sajana, Numerical Analysis on Behavior of Reinforced Concrete T-Beam with Shear Strengthening using U-Strap Steel Plates and Bolts, International Journal of Advanced Science and Technology, Vol. 29, No. 6, (2020), pp. 1181-1193.

[4] I K. Sudarsana, Retrofitting of Low Rise Reinforced Concrete Building Using External Bolted steel Plates: Case Studi-SPS Building, Jimbaran, Bali-Indonesia, Procedia Engineering 171 (2017). pp. 1147-1157.