Structural supports control how a structure transfers loads to the ground. Each support type restricts different combinations of movement and rotation, and choosing the wrong one means your model won't reflect real-world behavior. The most common types are fixed, pinned, roller, simple, sliding, cable, rocker, and elastomeric supports.
Key Highlights
Watch the video below to see how supports work in ADAPT-Builder before we break down each type.
A fixed support is the most rigid option available. It locks a member in place completely, preventing all movement and rotation in every direction. Think of a steel pole set in concrete. That pole can't twist, tip, or shift at its base. That connection point is fixed.
Characteristics
A fixed support restrains all translations and rotations at the connection point. It resists forces in every direction and prevents any rotational movement, making it the most fully constrained of all support types.
Applications
Fixed supports are the go-to choice when only one support point is available. A single fixed support can provide all the restraint a structure needs to remain static, which makes it the standard choice for cantilever structures.
Limitations
The rigidity that makes a fixed support so useful can also create problems. Some structures need a small amount of flexibility to protect surrounding materials. Concrete is a good example. As it cures and gains strength, it also expands. If the support doesn't account for that movement, the expansion can work against the structure over time and reduce its long-term durability.
Example
A steel pole embedded in a concrete foundation is a common real-world example. The base of the pole cannot move or rotate in any direction, which is exactly what a fixed support represents in a structural model. When designing fixed supports in concrete, ACI 318 governs how the connection must be detailed to ensure the support performs as intended under the required load combinations.
Watch the video below to see how to support vertical elements above a reference plane in ADAPT-Builder.
A pinned support works like a hinge. It allows rotation to happen freely but prevents any translation, meaning it resists both horizontal and vertical forces while allowing the connected member to rotate. Your elbow is a useful analogy here. You can bend and straighten your arm, but you can't slide your forearm sideways from the elbow joint.
Characteristics
A pinned support resists both horizontal and vertical forces but does not resist moment. The connected member is free to rotate at the joint but cannot translate in any direction.
Applications
Pinned supports are commonly used in trusses. When multiple members are connected through hinge-style joints, they push against one another and create axial forces within each member. Because the joints allow rotation, no internal moment forces build up. That means each member can be designed based on axial force alone, which simplifies the analysis considerably.
Limitations
A single pinned support cannot fully restrain a structure on its own. You need at least two supports to adequately resist moment forces and keep the structure stable.
Example
Truss bridges are a classic application of pinned supports. The hinge-style connections at each joint allow the individual members to carry axial loads without developing internal moments. For steel structures, AISC 360 provides the design requirements for pinned connections, governing how the joint must be detailed to handle the axial and shear forces it will experience in service.
A roller support resists vertical forces but does nothing to resist horizontal movement. The connection is free to slide laterally because there's no restraint in that direction.
Characteristics
A roller support resists force in one direction only, typically vertical. It allows free horizontal translation and rotation, making it the least restrained of the common support types.
Applications
Bridges are the most common application. One end of a bridge typically uses a roller support to allow for small vertical displacements and the natural expansion and contraction that comes with temperature changes. Without this freedom of movement, thermal expansion would put damaging stress on the other supports.
Limitations
Because a roller support offers no horizontal resistance, it cannot function as a standalone support. It always needs to be paired with another support type that handles lateral forces.
Example
A simply supported beam with one pinned end and one roller end is one of the most common configurations in structural engineering. The roller allows the beam to expand and contract freely without inducing additional stress into the system. ASCE 7 accounts for thermal movement in its load provisions, which is part of why roller supports are a standard detail in bridge and long-span beam design across the US.
Cable supports work differently from every other support type on this list. They only resist tension forces, which makes them purpose-built for structures where loads are carried through tension rather than compression or bending.
Characteristics
A cable support resists tension forces only. It provides no resistance to compression. The high flexibility of cables allows them to adjust their geometry in response to applied loads, which is a defining feature of how they perform.
Applications
Suspension bridges are the most recognizable application. The cables carry the weight of the bridge deck and transfer those loads up to the towers and down to the anchorages. Tensile fabric roof structures and high-voltage transmission lines are two other common uses.
Limitations
Because cables can only handle tension, they are not suitable for structures that experience compression or reversal of load direction. Any situation where the cable might go slack or experience compression requires a different support solution.
Example
The Golden Gate Bridge is one of the most well-known examples of cable supports in action. The main cables run from anchorage to anchorage, suspending the bridge deck through a series of vertical hangers.
Elastomeric bearings are made from rubber-like materials that compress and flex under load. They resist vertical forces while allowing controlled movement in both translation and rotation.
Characteristics
Elastomeric bearings accommodate movement through the deformation of the bearing material itself rather than through mechanical sliding or rocking. They also absorb vibration, which extends their usefulness beyond simple load transfer.
Applications
Highway overpasses use them widely because they improve long-term durability and reduce stress concentration in the structure. In seismic zones, elastomeric bearings help isolate buildings from ground motion during an earthquake. Industrial facilities use them under heavy machinery to dampen vibration and protect the foundation.
Limitations
Elastomeric bearings have limits on how much movement and rotation they can accommodate before the material degrades. In high-displacement applications, they may need to be replaced more frequently or supplemented with other bearing types.
Example
Highway overpasses are one of the most common places to find elastomeric bearings in use. They sit between the bridge girders and the supporting piers, quietly absorbing movement and vibration across the full service life of the structure.
RISA's structural analysis and design software is built to help engineers model these conditions precisely. Whether you're working with a simple pinned connection or a complex bearing system, having the right tools makes it easier to get the analysis right the first time. Explore RISA's full product suite or start a free 10-day trial to see how it fits your workflow.