AN INTRODUCTION TO CONTINUOUS STEEL BEAM CONSTRUCTION

For stability with flexibility nothing beats roll former manufacturers continuous steel beam construction. Continuous steel beams are created by joining two or more beams rigidly together over multiple support points. This method of construction creates a stiffer and stronger member than a simple supported beam and is ideal for providing brace free spaces and flexible arrangements of columns.

If you need a building with open space, particularly near the roof or ceiling, continuous beam is highly recommended. Continuous steel beams allow for large, high door openings for large vehicles or other equipment as well as a floor with efficiently placed columns for forklift traffic. If your design does not include bracing, continuous steel beam can create a building frame strong enough to exclude it.

CONTINUOUS STEEL BEAMS: A DEFINITION
A continuous steel beam contains two or more beams joined by multiple beam supports. Spans are usually in a straight line and have two or more supports along the length of each beam.  It is moment-resisting at the rigid beam-to-column connection and provides frame stability and lateral load resistance solely through connection rigidity and member stiffness. Beam end moments and shear forces are transmitted into the column.

While these types of beams are typically used in bridges, they are also effective for single and multi-storey facility construction. Continuous beam construction is designed not just for strength but also for minimizing weight and material costs.

DESIGN FACTORS

You must take two design factors floor deck roll forming machine in particular when designing this type of structure:

Strength of beam material
Load type
When analyzing required beam strength, a simply supported beam with only two supports can be analyzed using just the forces or loading of the beam (statistically determinant). A continuous steel beam is classified as statistically indeterminate; reactions at the supports must be calculated using both the deformation character (material strength) and the presence of more than two supports per beam (load type).

The most common frame designs are those with an entire continuous frame and those with a discrete continuous frame. An entire continuous frame is built with all rigid joints. A discrete continuous frame only has rigid joints specifically where high loading is experienced, such as a specific area or room within the facility.

Be sure to take into account which directional forces are more prevalent as you determine realistic beam and column section sizes. Make this decision prior to frame design and analysis by looking at the primary use and environment of the building. A structure with loading mostly at the floor and roof has predominantly vertical loading. If the load is from wind, the bending moment will, of course, be mainly be on the horizontal.

SERVICEABILITY LIMIT STATE
A determination of realistic member sizes is also required to calculate the serviceability limit state, or SLS. Adequate resistance to lateral loading at the SLS is required in multi-storey buildings constructed without bracing. The relative horizontal deflection between floors must be controlled and limited to a particular magnitude. By calculating realistic member sizes prior to final design, it is easier to predict frame behavior at the SLS.

The serviceability limit state is balanced with safety factors, which also influence beam size. The higher the required safety margin, the thicker the beam must be. However, a thicker beam will increase material cost. Do not sacrifice safety but do remember how it will impact beam thickness.

LATERAL DISPLACEMENT
Multi-storey continuous beam buildings require extra attention due to the lateral displacement between the base level and the first floor especially when using pinned column bases. (A plate is attached to the bottom of the column member to facilitate attachment to the floor using hold-down bolts.) Moment-resisting column bases may be required although both the foundation loading and the costs of construction will go up.

In addition, don’t forget to take vertical pattern loading into account during frame analysis for single and double curvature bending in the columns.

ADVANTAGES AND DISADVANTAGES OF CONTINUOUS STEEL BEAM CONSTRUCTION
Advantages

Continuous steel beam construction lends itself well to a variety of width and height requirements. Column placement and ridge design is highly flexible to accommodate different floor plans as well as a variety of rack systems and equipment storage.

Ridge design can be single slope, center ridge, or off center. Continuous beam design can also include the use of purlins or bar-joists in the secondary framing. Additionally, you can use different types of wall systems such as tilt-up, block, and conventional steel frame.

Other advantages include:

Lower deflections than simply supported beams
Lower sensitivity to vibration
Better performance in load reversal conditions like earthquakes
Increased redundancy
Disadvantages

Continuous beam construction does come with these considerations:

Construction, especially at the connections, is more complex and requires greater skill on the part of the construction team
There are increased internal forces within the columns
Structural costs are higher due to the requirement for rigid connections and more highly skilled labor
Because building a continuous beam frame can increase costs, cost efficiency can be realized through a combination of beam construction that includes both continuous and simple support beams.

CONCLUSION
Continuous steel beam construction is robust and stable yet provides flexibility in design, especially when using interior columns. It will work with a range of wall systems, including tilt-up and conventional steel construction and it can be used with almost any ridge design.

Continuous beam is an economical option when esthetics or facility requirements prefer a brace-free building such as one that stores oversized equipment or that has an open and airy appearance. Floor design is also highly flexible, with an endless array of selections in rack systems, wall systems, and floor lay-outs. Mezzanine, mechanical, and crane loads are all efficiently accommodated with continuous beam.

To make continuous steel beam construction even easier, software is available that greatly simplifies designing with continuous steel beam. Most applications have inputs for types of forces applied, beam shape, span between supports, material strength and properties, mechanical connections, and beam shape. The software then produces a design that meets those requirements.

If brace-free construction is part of your design, you can’t go wrong with continuous steel beam.