Engineering a sign that is safe, practical and durable is no small task , especially in a fast-paced, demanding business world where everything is expected instantly.
Speed should never come at the price of safety and quality, especially when installing signage that thousands of people may look at on a daily basis for a long time. There are several areas of concern that first need to be addressed in order to properly engineer a safe signage installation.
Public safety is the primary concern for any signage project. To be safe, the sign and its foundation must be strong enough to offset natural forces, or loads, that may continually challenge their durability.
– Three Types Of Natural Forces
There are three major types of loads: live loads, which are a temporary, moving weight such as a repairman inside a service box; dead loads, gravity-produced weights of the actual sign, foundation and support structure; and environmental loads, which are caused by natural environmental occurrences such as rain, snow, ice, wind and earthquake.
Of these environmental loads, which provide the greatest impact on signage design, wind is often considered the most significant because it can cause the most damage for the most geographic areas.
Ice and snow, on the other hand, are climate-specific concerns. In cold weather areas with high snowfall, frost heave, a condition in which soil with a high moisture content expands as water freezes, must be considered when determining design requirements and selecting foundation depths for signage.
Wind loading, a major cause of damage, occurs when a rotational force, called a moment, is applied to the sign and its foundation, causing the sign to pivot from its column. The stronger the wind, the stronger the moment that weighs against the sign.
If the engineer overseeing a sign installation does not accurately account for wind loading, over time the sign may suffer from fatigue stress damage, particularly in areas with frequent high wind conditions. Fatigue stress damage can lead to structural failure because it causes signs to keep bending back and forth until they eventually weaken and fail.
Such damage can be prevented by incorporating a decreased allowable stress level into the sign’s design. In areas with constant high winds, such as Las Vegas or Chicago, it may be beneficial to design for an even lower stress level than what the local building code specifies, just to be extra cautious.
– Maintaining Healthy Signage
It is often assumed that once a sign is engineered and built, it will last forever. However, lack of maintenance is a major reason why signage structures fail to maintain intended longevity.
Signs should be regularly examined for weakened connections and overstressed members by an inspector with the construction documents readily available to determine if original design requirements were met accurately and to make any adjustments for future maintenance.
Proper maintenance and inspection can help identify potential risks for sign failure. Signs should generally be inspected every six months to a year to identify potential problems or risks imposed by the environment. In addition to wind damage, other risks include corrosion due to water, salt and acid rain.
An inspector should be able to identify rusted or broken bolts, corroded welds and loose connections. The sign base needs to be checked for proper drainage away from base metals. Pedestals can be over-landscaped and buried and should be routinely cleaned and maintained.
Owners also should incorporate a routine painting schedule as part of their maintenance, using rust-proof paint to keep steel and metal signs healthy.
– Two Functions Signs Perform
The goal behind successful signage is to aesthetically enhance an environment while providing useful information to businesses and consumers. After the installation and maintenance of a sign is properly secured, signs perform two major functions:
o First, signs serve as public informants, displaying a concise, well-planned message to hundreds, sometimes thousands of people every day.
Signs can serve as a crucial source of directional information to guide customers to business sites, or they can serve as advertisements for a business. In either case, signage can benefit the community by keeping the public informed and increasing local business revenues, which radiates to the surrounding community.
o Second, successful signage should convey a strong aesthetic appeal.
Simply put, signage is an extension of a business’ motto or persona, so being as creative and expressive as possible while still communicating a clear message is a challenging but worthwhile goal. Well-designed signs should be visually pleasing to the public , eye-catching and memorable without being too ostentatious.
– Other Issues For Owners
As with any other area of business, it is helpful for owners to develop some working knowledge of basic signage principles in addition to finding a qualified and reputable designer, fabricator, engineer and inspector.
Understanding some of the basic engineering calculations that can assist in properly sizing structures and foundations at the design phase will help ensure that a process is done accurately and professionally.
Once an engineer is in place, be sure that engineering cost estimates specify that engineering fees required for obtaining permits are reimbursable fees. Once you sign off on a fee agreement, you could get locked into paying costs you thought were nailed down, so to speak.
Properly engineering a signage installation is one thing. Ensuring its safety, durability, and effectiveness over a long period of time is another thing.
The biggest mistake site owners make with the signage process is that they assume that once their sign is erected, the process is complete. On the contrary , it’s just the beginning. Investing in an engineer, inspector and maintenance schedule that will extend a sign’s longevity and properly convey a public message is worth the upfront time and investment.
Agost is the senior engineer for Structural Technology Consultants, a structural engineering firm in San Diego with a full-service sign division.
