Fiberglass deck systems are becoming increasingly popular due to their numerous advantages over traditional materials such as concrete and wood. These advantages include lightweight, high strength-to-weight ratio, corrosion resistance, and ease of installation. However, when it comes to designing these decks, it’s important to consider their effective width in relation to wheel or other point loads.
Fiberglass deck systems typically have skins that are integrally connected through the thickness with fiberglass webs are typically referred to as sandwich panel systems. These deck systems consist of two relatively thin, continuous fiberglass skins that are separated and connected by fiberglass webs. The skins are the load-bearing components of the panel and are designed to resist tensile and compressive stresses, while the webs serve as the shear connectors between the skins. The skins and webs are manufactured together in a continuous process, creating a strong, durable bond between the skins and webs. These systems can either be pultruded or vacuum infused.
In fiberglass decking applications, there are two types of designs for the deck systems: unidirectional and bidirectional. Unidirectional decks have panel webs that all go in the primary load direction only, while bidirectional decks have panel webs that go in both primary and secondary load directions. The effective width for these two types of decks can differ significantly due to their different design approaches.
Physical testing, Finite Element Analysis (FEA) and real-world application evaluations have shown that unidirectional fiberglass decks have an approximate effective width of 0.41 times the span length, while bidirectional fiberglass decks have an approximate effective width of 0.9 times the span length. This significant difference can be attributed to the different panel web orientations and the resultant load distribution mechanisms.
On the other hand, bidirectional fiberglass bridge decks have panel webs that are aligned with both the primary and secondary load directions, which means the load distribution is more evenly distributed. This results in a larger effective width, as a greater portion of the deck contributes to the load-carrying capacity of the structure.
It’s essential to note that the effective width of a fiberglass bridge deck can also be influenced by other factors such as the deck’s skin thickness, skin fiber orientation, and the thickness and spacing of the primary and secondary webs. These factors can affect the load distribution mechanism and consequently, the effective width.
In conclusion, the effective width of a fiberglass bridge deck is an essential factor to consider in its design. Unidirectional and bidirectional fiberglass bridge decks have significantly different effective widths, with unidirectional decks having a smaller effective width than bidirectional decks. However, other factors such as the deck’s skin thickness and web structure can also affect the effective width. Therefore, it’s crucial to consult with an experienced engineer or the manufacturer to determine the most appropriate effective width for a particular fiberglass bridge deck system.