We study the structural response of concrete weight coating of offshore pipelines subject to various loading conditions by utilizing the Lattice Discrete Particle Model and Finite Discrete Element Method in a comparative manner. We use laboratory experiments to validate our numerical simulations. We discuss the framework in detail, experiment setups, and outline the capabilities and limitations of both methods. A parametric study with a correlation to the size effect is also presented. We simulate Uniaxial Compressive Strength, Brazilian Disk and a three-point bending of a beam with a notch in both methods. We observe that strength and macroscopic fracture patterns fit well between numerical and experimental methods. We discuss the effectiveness of the methods concerning the transition of size effect, as well as comparing to the size effect law. Our statistical analysis quantifies the capability of capturing the size effect in both models. Capturing the size effect helps to increase the accuracy of predicting the structure response and performance which in turn a key factor in durability of concrete structures.