When you plan to start with your next structural steel construction project, you might think that the terms ‘girder’, or ‘beam’ can be used interchangeably. Many people confuse girder with beams as they resemble each other. But, the fact is that girders are a type of steel beams. In simpler words, all girders are beams, but not all beams can be called girders. To help you know more about how girder is different from the beam, here are some points that we want you to explore to know.
Beam | Girder | |
| Basics | Beams are a primary part of the structural framing system, designed to carry distributed loads of any structure. These beams are the most common designed elements of the structure to resist loads as its primary mode of deflection is bending. | Girder is a type of the beam that supports other smaller beams, thus acting as the main horizontal support of a structure. Unlike beams, girders are designed to support significant concentrated loads such as columns or beam reactions. The load-bearing capacity of a girder is much higher than the beams. It supports the vertical loads of the beams. |
| Size | Another difference between the girder and the beam is the size of the component. In the construction industry, large beans are referred to as the girder. There is no strict length, width, or weight cut offs that decide if it is a beam or girder. Instead, the builders decide according to how the component is used. If the component is smaller in size, it is a beam. | All girders are beams as they are the main horizontal support structures for smaller beams. If the builder has used the component to support all other smaller beams, it is referred to as a girder. But, there are no strict rules mentioned in the National Building Code of Canada regarding the dimensions of the girder to distinguish it from the beam. |
| Functionality | Both the components behave to resist the forces of bending. Beams typically have the I-shaped cross-sections composed of two load bearing flanges and web for stabilization. Beams support the structural integrity of the buildings can be found in floors, walls, roofs, ceilings, and decks. | A girder is a type that supports the beams and acts as the main horizontal support of the structure. Like beams, girders typically have the same I-shape design. They may also take on a box or Z-shape as well as other forms of design. Since girders mainly support smaller beams and construct the bridges and flyovers, they are capable of carrying extremely heavy loads. |
| Type | Beams are classified into several different types on many factors. Based on the kind of support that the beam provides, they are classified into - simply supported, fixed, continuous, cantilever and trussed beams. They are also classified on the geometrical aspect as a straight, curved, and tapered beam. Additionally, they are also divided into I-beams, T-beams, and C-beams. | A girder is typically used to refer to a steel beam. The most common girder used in any structural steel construction project is I-beams. Even box girders are mainly used in the construction of elevated bridges and roadway flyovers. Box girders are made of two steel webs joined together at the top and the bottom by the flanges. This creates a closed cell that provides good torsional stiffness, a quality required for the curved bridges. |
| Load-bearing capacity | Beams can carry weight. But, when you compare it with the girders, the capacity is much lesser in terms of the structural design of the component and the capacity level. Beams cannot hold the same weight that the girders can hold. | Girders are made to carry dynamic and rolling loads. Therefore, many builders mostly prefer girders for structural steel construction projects where the loads are not very constant. When it comes to carrying the dynamic loads, it refers to the exert varying amounts of the force of a structure. They are contrasted with static loads, thus exerting the same amount of force at all times. Therefore, you need a special kind of beam to withstand the dynamic loads with consistent and unfailing strength capacity that only girders can provide. |
| Jobs | A beam is a secondary beam or stiffener. Its main job is to transfer the loads to girders. Beams bend to accommodate shear stresses. | Girder is a primary beam. Its main job is to transfer the loads to the columns upon which it rests. Girders are more stiff to support the small beams. Stiffeners support the plating, girders support the stiffeners or other girders. |
| Fabrication | During the designing stage of the beam, the fabricators must consider the requirements such as holding the structure and transferring the load to the girder. Custom steel beam fabrication is an efficient and cost-effective way to ensure you get the exact horizontal support structure that you require in your structural steel construction steel project. | On the other hand, fabricators carefully consider the requirements such as the erection of the girder, stability, deck placement sequence, plate sizing, welded connections, and flange sizing. Girder fabrication might cost more than the beam fabrication. For girders, you need a team of qualified structural steel fabricators to fulfil the industrial fabrication task of the girder. |
Steel is tested before it leaves the factory to ensure that it meets the specifications defined by the engineers who design the bridges or any other construction projects. It is clear why structural steel is used to build structures with steel girders and beams. Now that you know the difference between a girder and a beam, you can now use these two components wisely during the structural steel construction projects.
