Structural loads are forces applied to a component of a structure or to the structure. Design loads are specified in national codes for types of structures, geographic locations, and usage. In addition to the load magnitude, its frequency of occurrence, distribution, and nature (static or dynamic) are important factors in design. Loads cause stresses, deformations and displacements in structures. Assessment of their effects is carried out by the methods of structural analysis. Excess load or overloading may cause structural failure, and hence such possibility should be either considered in the design or strictly controlled.

The following lists the common loading types primarily for civil infrastructure and land machinery. Structures for aerospace (e.g. aircraft, satellites, rockets, spacestations, etc..) and marine (e.g. boats, submarines, etc..) environments would have their own particular design loads and considerations.

Dead loads

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Dead loads consist of weights of material, equipment or components that are relatively constant throughout the structure's life.

Live loads

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Live loads are temporary, of short duration, or moving such as snow, wind, earthquake, traffic, movements and occupancy loads.

Environmental loads

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• Temperature changes or thermal load
• Humidity or moisture induced expansion
• Ice movements
• Water waves
• Shrinkage

Extreme loads

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• Blast and impact loads
• Hurricane
• Windborne or blast generated debris/missile impacts.

Static loads

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These are loads that build up gradually over time, or with negligible dynamic effects. Since structural analysis for static loads is much simpler than for dynamic loads, design codes usually specify statically-equivalent loads for dynamic loads such as wind loads or earthquake loads.

Dynamic loads

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These are loads that create significant dynamic effects such as impact loads, waves, wind gusts, strong earthquakes. Because of the complexity of analysis, dynamic loads are normally treated using statically equivalent loads for routine design of common structures.

Load combination

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A load combination is a combination of more than one load type. Design codes usually specify a variety of load combinations together with the weighting factors for each load type.

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