Search

An empirical model, which predicts the shear strength of interior reinforced concrete (RC) joints exposed to cyclic loading, is developed using gene expression programming (GEP). Five main parameters are used to develop the GEP model including concrete compressive strength, joint transverse reinforcement, beam reinforcement ratio, joint aspect ratio, and joint width. A large database including 160 data test points is used to test and train the GEP model. The GEP model is then evaluated using the coefficient of determination (R2). The formulation proposed by ACI-352 is used to predict the shear strength of RC joints. The R-squared values of the ACI and the GEP model are 66% and 87% respectively which indicates that the joint shear strength predicted using the GEP model is closer to the experimental results than that predicted using the ACI-352 formulation.

The Dynamic Replacement (DR) technique has been used successfully to improve soft soils. It uses the dynamic compaction energy to drive granular materials down into the soils, forming a pillar of 2–2.5 m diameter. In this paper, a 30,000 m2 study is used to evaluate the performance of the technique. Cone penetration tests (CPTs) were carried out before ground improvement to analyze the soil and select the appropriate technique. Post improvement CPTs (inside and between pillars) and load tests were carried out to confirm that the design requirements (bearing capacity and settlement) are met. It is proposed to use the Schmertmann [1] and Schmertmann et al. [2] method for calculating the settlements. However, to make it applicable to the case of DR for clayey soils, a methodology is proposed to calculate an equivalent tip resistance based on the DR replacement ratio. The values of the equivalent tip resistance are used to calculate the equivalent modulus of elasticity of the soil for settlement calculations. A finite element model has been built to simulate the revised formula, and the calculated settlements have shown a good agreement with the conducted measurements and the finite element model results as well. Keywords: Dynamics, Site investigation, Geotechnical engineering