Structural Engineering is that part of engineering that covers the planning, design detail and management of all initiatives that have influence on the lives of human beings, such as water tanks, roads, bridges, irrigation structures, residential buildings, etc. Structural engineers are most commonly involved in the design of buildings and large non-building structures, but they can also be involved in the design of machinery, medical equipment, vehicles or any item where structural integrity affects the item's function or safety. Structural engineers must ensure their designs satisfy given design criteria, predicated on safety (e.g. structures must not collapse without due warning) or serviceability and performance (e.g. building sway must not cause discomfort to the occupants). Buildings are made to endure massive loads as well as changing climate and natural disasters. Structural engineering theory is based upon physical laws and an empirical knowledge of the structural performance in different types of landscape with different materials. Structural engineering design uses a relatively small number of basic structural elements to build up structural systems that can be very complex. Structural engineers are responsible for making creative and efficient use of funds, structural elements, and materials to achieve these goals.