Fiberglass reinforced plastics as composite materials possess mechanical properties that each constituent cannot provide individually. These properties include high strength per weight, corrosion and fire resistance, and cost per performance advantage. We have designed the corrugated and ribbed sections of Tuff Span panels to provide efficient high strength, rigid, and economical structural components for use in industrial buildings. Design parameters used to prepare the load/span tables are based on results from a series of large-scale tests. We test full-size corrugated panels under uniform and concentrated loading conditions using two span vacuum box and three point load tests. Test results are based on an ambient temperature of 77° F. The critical stress at failure (e.g., maximum deflection (L/D) governs the allowable load and span of a panel section. Critical stress is limited by stability failure ( collapse of corrugations), material failure, or fastener pullover. Factors of safety are then applied judiciously to obtain the load/span relationship. |
These tables do not consider the effects of corrosive environments or elevated temperatures on panel strength or rigidity. You should reduce these factors appropriately, or apply an additional factor of safety to the expected loads, for such applications, especially where safety is a consideration
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Under service conditions, the primary modes of failure for panels are fastener pullover, web crippling, flange buckling, tension failures or compression failures. These modes are classified as either resin control or fiber control failures.
Fiber control failures can be tensile or compressive failures. They can also be failures caused by excessive deflection. Fiber control failures occur when the material does not provide sufficient strength and stiffness to the panel to withstand the applied loads.
Resin control failures occur when the deterioration of the resin binder weakens the material and causes structural failures. Chemical attack, water absorption, elevated temperatures, and creep can initiate the panel degradation.
Fastener pullover occurs when a panel under negative load pulls over the washer and screw head. The situation arises when there is a sufficient suction pressure, combined with internal pressure inside a building, to create failure at attachment points. Wind loading subjects a building to both the external pressures from the direct impact of the wind and the outward (negative or uplift) pressures created by an interaction of the air motion and the structure. It is essential to consider negative loads when specifying roofing and siding materials.
Material failure occurs when forces stress the panel material to its ultimate strength. This is the ideal mode of failure because it provides the greatest panel capacity. Web crippling and flange buckling are local instability failures that cause corrugations to collapse. The critical stresses at failure are smaller than the material ultimate stresses. Different panel sections yield different levels of critical stresses.
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Accurate and reliable performance data is determined from large scale tests that simulate actual installations. Photos show materials tested to failure.
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| Pullover - Punch Out Type Tests | Pullover - Simulated Full Span Bending Test | Compression Failure - Three Point Loading Test | Web Crippling Failure - Vacuum Box Panel Loading Test | Flange Buckling Failure - Vacuum Box Panel Loading Test |
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A Factor of Safety (FOS), as employed for Tuff Span panels, is the ratio of the ultimate capacity to the allowable actual working capacity of the component. The FOS must consider many factors, including the degree of certainty and precision available for determining component mechanical properties, stress, and overall performance under loading conditions. It must also consider the deterioration due to environmental conditions, full-scale loading conditions, and all uncertainties that can contribute to the probability of failure as well as the degree of its consequences.
It should be noted that the design wind speeds specified in building codes may never be reached in the life of the structure. For this reason, most codes allow some reduction in the FOS for wind loading. If you need to determine the negative pressure created by wind loads, you should multiply the dynamic wind pressure by the shape factor as specified by the applicable building code. The panel tables are based on the FOS of 2.5 for live loads (other than wind) and 1.88 (75% of 2.5) for wind loads.
These Factors of Safety cover conditions for industrial buildings. Larger FOS should be applied in accordance with the nature of loading and actual service conditions.
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Fiberglass reinforced
plastic has a relatively high strength to modulus ratio, and most FRP
designs are deformation controlled rather than stress controlled. The
ratio between the span length and its maximum deflection (L/D) gives the
deflection ratio.
The value to which the span to deflection ratio (L/D) is limited is an
important design criteria. The limit should be set with these factors
in mind:
- section shape,
- section function as a structural component,
- type of loading.
The L/D limit as applied in these tables will prevent excessive span deflection and enlargement of the fastener holes
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Strength properties of reinforced plastics are reduced under continuous exposure to elevated temperatures. And elevated temperatures can accelerate the effects on FRP of exposure to sustained load and hostile conditions (chemicals, moisture, ultraviolet rays, etc.).
Plastic based materials, more than other building materials, are susceptible to creep, especially at high service temperature. You should consider the effects of service environments on FRP when choosing the type of resin and reinforcing systems you need in your FRP structural components.
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When designing with Tuff Span products in applications with continuous elevated temperatures, the strength properties should be reduced using these guidelines.
| Temperature °F | Minimum Strength Properties Retention % | |
| Polyester | Vinyl Ester | |
| 77 | 100 | 100 |
| 100 | 87 | 98 |
| 125 | 72 | 95 |
| 150 | 55 | 92 |
| 175 | - | 85 |
| 200 | - | 65 |
| 225 | - | 42 |
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All plastic based components deform when they are subjected to a sustained load. Deformation continues indefinitely or, if the load is high enough, until rupture occurs. Tuff Span load/span tables contain Factors of Safety. When the tables are observed the possibility of rupture is eliminated.
We apply design and product considerations to keep the actual stress and strain levels within Tuff Span products under specific limits. This allows the control of creep to a satisfactory level during the service life of the product. Our tables reflect these considerations and are based on long-term testing of materials under sustained loads.
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Plastic based materials experience physical and appearance changes during exposure to weathering and ultraviolet rays. The following protective means are available for Tuff Span products:
- U.V. stabilizers ( acrylic monomers, standard) are added to the resin system to retard weathering effects.
- Surfacing mats (standard) are added to retard weathering and resist corrosion.
- Surfacing veils (optional) are available for further weather and corrosion resistance.
- Acrylic Polymer coatings are added as a finish coat to protect against damage due to ultraviolet rays.
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You can use Tuff Span panels to create aesthetically pleasing designs. A number of standard colors are readily available, and custom colors can be created to match existing materials or color schemes.
Translucent panels are available also. Translucent panels admit daylight and so brighten work environments. This can contribute to worker safety and job satisfaction.
See the Material Description page for a listing of Tuff Span standard colors and light transmission factors.
Some product discoloration may occur under certain atmospheric and environmental conditions beyond our control. A stack of panels can trap heat and moisture that may cause clouding. See page 24 for correct storage and handling procedures.
Slight color variations may occur between production runs and between opaque and translucent panels in the same color. If color matching is critical, contact your sales engineer.
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Chemical exposures and operating conditions vary widely from industry to industry. Because of this, Tuff Span panels are available in three resin systems. This allows you to tailor a Tuff Span panel to meet your specific needs.
Premium Grade Isophthalic Polyester Resins are recommended for environments exposed to splash and spill chemicals and moderate operating temperatures.
Vinyl Ester Resins are recommended for environments exposed to severe chemical condenses and high operating temperatures.
Series FM Polyester Resin has demonstrated excellent resistance to chemical attack from vapors and moderate condensates produced by certain acids and bases (see FM Resin Guide). Contact your Tuff Span Sales Engineers for recommendations on specific applications.
| Series FM Exposure Guide | ||
| Chemical | % | Maximum
Operating Temperature (°F) of FM Polyester |
| Alum | Vapor | 120 |
| Hydrochloric Acid | Vapor | 120 |
| Sodium Hypochlorite | Vapor | 120 |
| Sodium Hydroxide | Vapor | 120 |
| Sulfuric Acid | Vapor | 120 |
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It is important to consider the effects of corrosion on materials in the design stage. Many factors should be evaluated, including chemical type, concentration, type and duration of exposure, and operating temperature.
You should contact your Tuff Span sales engineer or our headquarters if you need a recommendation for a specific application. Also, we can help you select the appropriate materials for environments and exposures not covered in this Guide.
| Chemical | Maximum Operating Temperature (°F) | ||
| % | ISO Polyester | Vinyl Ester | |
| Acetic Acid | 10 | 150 | 210 |
| Acetic Acid | 50 | 125 | 180 |
| Acetone | All | NR | NR |
| Alum | Vapor | 150 | 210 |
| Aluminum Sulfate | 5 | 150 | 210 |
| Aluminum Potassium Sulfate | All | 130 | 210 |
| Ammonia | - | - | 100 |
| Ammonium Hydroxide | 10 | NR | 160 |
| Benzene | All | NR | NR |
| Benzensulfonic Acid | 30 | NR | 210 |
| Bromine | fumes | NR | 70 |
| Calcium Chloride | All | 150 | 210 |
| Carbon Tetrachloride | Vapor | 70 | 70 |
| Chlorine (Gas Wet) | All | AMB | 220 |
| Chromic Acid | 5 | - | 100 |
| Cooling Tower Water | - | 130 | 170 |
| Copper Sulfate | All | 120 | 210 |
| Dibutyl Phthalaic | 100 | 70 | 150 |
| Ethylene Chlorohydrine | All | NR | 100 |
| Ethyline Dichloride | All | NR | 100 |
| Ethyl Ether | All | NR | NR |
| Ethylene Glycol | All | 150 | 210 |
| Ferrous Sulfate | All | 150 | 210 |
| Fatty Acids | 100 | 150 | 210 |
| Flousilicic Acid | 10 | 100 | 150 |
| Fungicides, Organic | - | 125 | - |
| Gasoline | 100 | 100 | 100 |
| Hydrochloric Acid | 1 | 150 | 210 |
| Hydrochloric Acid | 15 | 150 | 210 |
| Hydrochloric Acid | 32 | 90 | 180 |
| Hydrochloric Acid | Vapor | 150 | 210 |
| Hydrogen Chloride (Gas) | 100 | 120 | 210 |
| Hydrogen Sulfide | All | 140 | 210 |
| Kerosene/Fuel Oil | 100 | 150 | 180 |
| Magnesium Chloride | 100 | 150 | 210 |
| Methyl Alcohol | 100 | AMB | NR |
| Mineral Oil | 100 | 150 | 200 |
| Naptha | 100 | 150 | 180 |
| Nitric Acid | 5 | 150 | 150 |
| Nitric Acid | 60 | NR | 160 |
| Phosphoric Acid | 10 | - | 210 |
| Phosphoric Acid | 30 | - | 210 |
| Phosphoric Acid | 85 | 150 | 210 |
| Potassium aluminum Sulfate | SATD | 130 | 210 |
| Sodium Bicarbonate | 10 | 120 | 180 |
| Sodium Bisulfate | All | 150 | 210 |
| Sodium Carbonate | All | 70 | 160 |
| Sodium Chloride | SATD | 150 | 210 |
| Sodium Hydroxide | 5 | NR | 150 |
| Sodium Hydroxide | Vapor | 150 | 180 |
| Sodium Hypochlorite | 5 | 120 | 150 |
| Sodium Hypochlorite | Vapor | 150 | 150 |
| Sodium Nitrate | All | 150 | 210 |
| Sodium Silicate | All | NR | 210 |
| Sodium Sulfate | All | 150 | 210 |
| Soya Oil | 100 | 130 | 180 |
| Styrene | 100 | NR | NR |
| Sulfite Liquors | - | 120 | 210 |
| Sulfur Dioxide | Dry | 150 | 210 |
| Sulfur Dioxide | Wet | 150 | 210 |
| Sulfur Trioxide | 100 | AMB | 210 |
| Sulfuric Acid | 25 | 120 | 210 |
| Sulfuric Acid | 50 | NR | 210 |
| Sulfuric Acid | 70 | NR | 160 |
| Sulfuric Acid | Vapor | 150 | 210 |
| Trisodium Phosphate | 25 | - | 210 |
| Water Distilled | 100 | 140 | 210 |
| Water (city/sea) | 100 | 150 | 210 |
| Zinc Sulfate | All | 150 | 210 |
| Design
engineers and plant personnel should use this Guide as an aid in the
selection of an appropriate resin system for their specific application.
Since specific job applications will vary, this information should
be used as a guide only and it cannot be considered a guarantee of
performance. The Polyester and Vinyl Ester chemical resistance guide is to be used for standard Tuff Span isophthalic polyester and vinyl ester fire-rated panels only. The resin system for the Series FM material is a specially formulated isophthalic polyester with specific additives for enhanced fire retardance. The chemical resistance of Tuff Span Series FM polyester should not be considered the same as standard isophthalic polyester or vinyl ester. |
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