What is a structural engineer?
Structural engineers analyze, design, plan, and research structural components and structural systems to achieve design goals and ensure the safety and comfort of users or occupants. Their work takes account mainly of safety, technical, economic and environmental concerns, but they may also consider aesthetic and social factors.
Structural engineering is usually considered a specialty discipline within civil engineering, but it can also be studied in its own right. In the US, most practicing structural engineers are currently licensed as civil engineers, but the situation varies from state to state. In the UK, most structural engineers in the building industry are members of the Institution of Structural Engineers rather than the Institution of Civil Engineers.
Typical structures designed by a structural engineer include buildings, towers, stadia and bridges. Other structures such as oil rigs, space satellites, aircraft and ships may also be designed by a structural engineer.  Most structural engineers are employed in the construction industry, however there are also structural engineers in the aerospace, automobile and shipbuilding industries. In the construction industry, they work closely with architects, civil engineers, mechanical engineers, electrical engineers, quantity surveyors, and construction managers.
Structural engineers ensure that buildings and bridges are built to be strong enough and stable enough to resist all appropriate structural loads (e.g., gravity, wind, snow, rain, seismic (earthquake), earth pressure, temperature, and traffic) in order to prevent or reduce loss of life or injury. They also design structures to be stiff enough to not deflect or vibrate beyond acceptable limits. Human comfort is an issue that is regularly considered in the limits. Fatigue is also an important consideration for bridges and for aircraft design or for other structures which experience a large number of stress cycles over their lifetimes. Consideration is also given to durability of materials against possible deterioration which may impair performance over the design lifetime.