A cantilever beam is a structural member that is fixed at one end and free at the other, allowing it to extend outward without additional vertical supports. The fixed end anchors into a rigid support such as a wall or column, which resists the forces created by the load on the projecting section. When weight is applied to the cantilever, the beam experiences compression in the upper fibers and tension in the lower fibers, creating a bending moment that must be resisted at the fixed support. Engineers design cantilevers using materials such as reinforced concrete, steel, or engineered wood to handle these stresses safely. Cantilever systems are commonly used in balconies, overhangs, bridges, and sign supports because they allow structures to extend outward while keeping the space below unobstructed.
Week 3 – Structural Truss
A truss is a structural framework made of interconnected members arranged in triangular shapes. The triangular geometry makes trusses extremely strong and efficient because triangles maintain their shape under load and distribute forces through the structure. When weight from a roof, bridge deck, or other load is applied, the forces are transferred through the truss members as either tension (pulling) or compression (pushing). Instead of bending like a solid beam, each member primarily carries axial force, which allows the structure to span longer distances while using less material. Because of this efficiency, trusses are commonly used in roof systems, bridges, and large open spaces where interior supports would be undesirable.
Week 4 – Shear Wall
A shear wall is a vertical structural element designed to resist lateral forces, such as wind or earthquakes, that push against a building from the side. Unlike beams and columns, which primarily carry vertical loads, shear walls provide stiffness and stability by preventing a structure from swaying or twisting. When lateral forces act on a building, the shear wall transfers these forces down through the structure and into the foundation. Shear walls are often made from reinforced concrete, masonry, or wood framing with structural sheathing such as plywood or OSB. In many buildings, shear walls are located around stairwells or elevator cores, where they form a rigid central spine that stabilizes the entire structure.
Week 5 – Moment Frame
A moment frame is a structural system that resists lateral forces such as wind or earthquakes through rigid connections between beams and columns. Unlike simple beam-column connections that allow rotation, moment frame joints are designed to be stiff so that the beam and column act together as a single unit. When lateral forces push on the building, the rigid joints transfer bending moments through the frame, allowing the structure to resist deformation without relying on diagonal bracing or solid walls. This allows architects to create buildings with large open spaces and fewer walls, which is why moment frames are commonly used in steel buildings, parking garages, and commercial storefronts. The strength of the system comes from the stiffness of the beam-column connections and the ability of the members to resist bending.
Week 6 – Pile Foundations
A pile foundation is a type of deep foundation used when the surface soil is too weak to support the weight of a structure. Instead of relying on shallow footings near the ground surface, piles are long columns made of steel, concrete, or wood that are driven or drilled deep into the ground until they reach stronger soil layers or bedrock. The structural loads from the building travel down through the columns and foundation system into the piles, which transfer the forces either through end bearing at a strong layer or through skin friction between the pile surface and surrounding soil. This system allows heavy structures such as skyscrapers, bridges, and waterfront buildings to remain stable even when built on soft or loose ground.
Lars is a half Danish half American US Army veteran and current student at City College of San Francisco.
He is studying for a bachelors of science in construction management. This blog is for his architecture 127 class.
Lars Nash ARCH 127 Structural Diary 