Civil engineering and mechanical engineering often intersect in various aspects of structural and infrastructural development. Can you discuss, in detail, the theoretical considerations that must be addressed when integrating mechanical systems into large$-$scale civil engineering projects, such as skyscrapers or bridges? Your response should cover the principles of load distribution, thermal expansion, vibration control, and material selection, particularly focusing on how mechanical engineers collaborate with civil engineers to ensure the integrity and functionality of the structure. Additionally, explore the theoretical frameworks that guide the design of mechanical systems to withstand natural forces such as wind and seismic activity, and how these frameworks influence the overall architectural design. Provide an analysis of the balance between innovative mechanical solutions and traditional civil engineering practices, considering the long$-$term sustainability and maintenance of the integrated systems.