Capturing the mechanical response of engineering structures and analyzing product designs can be complicated. Such a response is attributed to several factors, including the materials used, topological properties, and even the nature of external loads. One way of facing this challenge is to systematically tackle the details and build the full picture. In this learning track, titled "Capturing Complex Response of Structures," we introduce constitutive laws that govern both material behavior and the interactions between different bodies. The objective of this track is to connect the dots between different factors affecting a structure's response and learn how they play in tandem to result in a complex response. This learning track is the first step towards studying advanced topics in applied solid mechanics and is based on the strong fundamentals learned in the prior learning track titled "Physics of Structural Mechanics."