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beam design

Methods for Measuring Bending Stresses in Structural Engineering

Measuring bending stresses is an important part of structural engineering. Measuring bending stresses determines how much load a structure can support before it fails. Building structurally sound projects is the ultimate goal of successful structural engineering.

Measuring Bending Stresses

Measuring bending stresses requires determining the average amount of force exerted on an area that results in distortion or failure of the material. Understanding these values is crucial in determining the limits of construction materials.

Methods for Measuring Bending Stresses in Commercially Available Construction Materials

With the advent of new composite materials, measuring bending stresses has become a crucial ongoing investment of research dollars for scientists and engineers. One of the newest methods of measuring bending stresses is the use of piezoelectric PVDF (polyvinylidene-fluoride) film sensors.

Researchers have reported that a 25 µm thick PVDF strip used as an embedded interfacial stress sensor on aluminum and composite beams adequately measures bending stresses of the building materials. Engineers have also used these PVDF strips to measure other forces such as interfacial stresses and the adhesion strength of laboratory recreated layers of ice that might occur on the outside of a structure once constructed.

Another method of measuring bending stresses is to clamp gauges at key points of an existing structure to measure the bending moment of different types of materials used in the structure. By studying this data, scientists can learn vast amounts of information about the bending behavior of different construction materials once they are used in the field. This method also allows engineers to measure bending stresses over an extended period of time, allowing researchers to factor in other variables such as weather, corrosion, and alternating live loads.

Alternatively, engineers can measure bending stresses by attaching a hollow bar with strain gauges on its inner surface in a manner that allows part of the bar to move longitudinally along its axis with respect to the structure itself.

In Japan, researchers have experimented with measuring bending stresses in micro-cantilever structures by using a macro model using a micro-fizeau interferometer and the spatial fringe analysis method. Comparison of these test results with other measurements obtained from traditional gauge measurements shows that this method is effective in measuring bending stresses.

Other methods of measuring bending stresses indirectly are under consideration by the U.S. Patent Department and may revolutionize the way structural engineers study the measurement of bending stresses in the near future.

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Structural Engineering of Historic Buildings

The structural engineering of historic buildings is often focused on retrofitting these structures with life-saving alterations such as fire safety equipment and earthquake proof systems. Historic buildings are often built soundly, but due to the age of the building materials, the structure may be unstable or unsafe in the event of a fire or earthquake.

Most historic buildings are exempt from the newer federal building codes, but if the building owner wishes to change the use of the historic building, such as opening it up to public access or running a business from inside the historic building, certain building code requirements must be fulfilled. This most often results in calling in a structural engineer or architect to assist with the retrofitting or alteration of the historic building.

Structural Engineering of Historic Buildings: Energy Conservation

Some historic buildings require structural engineering expertise to aid in the conservation of energy. With today’s rising energy costs, energy conservation is a necessity for many building owners. This often involves placing insulating thermal paned glass over the historic glass of the buildings to help reduce heating and cooling costs.

The addition of awnings and shading devices can also help with energy conservation without altering the historic structure. Insulation is often added, and masonry walls can be coated with a waterproofing substance to further aid in energy conservation.

Structural Engineering of Historic Buildings: Seismic Retrofitting

Seismic retrofitting concentrates on preserving the structural integrity of the structure and reduce the likelihood of personal injuries should an earthquake occur. Seismic retrofitting also seeks to limit the amount of damage the historic building incurs during an earthquake.

Seismic retrofitting of a historic building may include bracing or tying parapets, chimneys, or ornamentation on the structure. It also involves reinforcing the emergency egress routes inside the building to help preserve life during an earthquake. Floor to wall framing may be enhanced and masonry walls often require addition support to limit the amount of damage from an earthquake.

Structural Engineering of Historic Buildings: Fire Safety Retrofitting

Fire safety retrofitting in historic buildings is a common occurrence. Retrofitting fire safety devices poses a unique problem for structural engineers. The fire safety systems must provide maximum protection in the event. Emergency exits are also examining and altered when necessary to provide a route of escape in the event of a fire. For a detailed government report about retrofitting of historical buildings for fire safety, view theThe General Services Administration “Fire Safety in Historic Buildings” Report Here.

The structural engineering of historic buildings is a delicate procedure that requires the skill and expertise of an experienced structural engineer and a team of consultants. The preservation of historic buildings is a specialty area and one of great interest to many citizens. For more information about the preservation of historic buildings, you can visit The National Park Service website.

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The Features and Benefits of Structural Engineering Software

Structural design software has many features and benefits for builders, contractors, architects, and even the industrious homeowner. Structural design software is a useful tool that saves time and money for anyone involved in building or remodeling structures. If you are considering purchasing structural design software for your business or personal use, this review of the features and benefits of structural design software will help you determine if an investment in structural design software is right for you.

Features of Structural Design Software

Not every structural design software program is the same. Some structural design software is very basic while other programs have extra features. Some structural design software is geared toward professional architects, contractors, and builders, and other programs are better suited for the homeowner remodeling his or her own house. A good structural design software program has features that are suited for a wide variety of uses and is easy to use, right out of the box.

A well-rounded structural design software program includes footing design, column design, and beam design. Structural design software should also include features for wood construction, steel construction, and manufactured building supplies.

An exceptional structural engineering software program also includes added features like flitch beam design, hip and valley beam design, international building codes, laterally loaded column design, local building codes, multi- span analysis, rectangular and continuous footing design, sheer and moment diagrams, steel angles, and wide flange steel columns.

Benefits of Structural Design Software

You may be wondering who uses structural engineering software. Architects, engineers, designers, and builders all benefit from using structural engineering design software. Structural engineering students and homeowners remodeling their home can benefit from structural engineering software.

Structural design software saves users time by streamlining the structural design process. A good quality structural engineering software program includes building codes that apply to your specific geographical location. This feature saves time by eliminating the extensive research and double-checking that would otherwise be required without the use of structural design software.

Structural design software also saves money. Not only does it cut costs by streamlining the design phase of construction, it eliminates costly mistakes and last minute alterations in the design of a structure. Using structural design software also ensures that structures meet all building regulations , thereby eliminating fines and costly alterations to bring a structure up to code.

Structural design software saves builders, architects, engineers, and designers time and money. Be sure to check out the features of a structural design software program before purchasing it, to ensure it meets your design needs.

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Commercial and High Rise Building Beam Design

Beam Design and Structural Design in Commercial and High-Rise Buildings

Beam design and structural design in high-rise buildings is constantly evolving. Structural designs are created to withstand earthquakes and high winds, conform to building codes, and construct impressive visual designs. Beam designs can significantly affect the stability of a high-rise building as well as the aesthetic appeal of a structure.

The structural design of a high-rise building is greatly dependent upon lateral loads. For this reason, bean design in high-rise buildings deserves careful consideration. Specially designed internal support system help keep the structure stable, especially in high wind and during earthquake tremors.

Factors Affecting Beam Design and Structural Design in Commercial and High-Rise Buildings: Drift and Acceleration

Another factor that plays into the beam design and structural design of commercial and high-rise buildings is drift. Drift is defined as the ratio of the building deflection over its height. Structural engineers must also take into consideration building acceleration when designing beams for commercial and high-rise buildings. Building acceleration is a measure of the speed with which drift occurs. This plays a critical role in the stability of a high-rise structure.

Beam Design in Commercial and High-Rise Buildings: Shear Wall Systems

One popular way to stabilize a high-rise building is by using shear wall construction. A shear wall is designed to withstand the combined forces of shear, moment, and axial loads caused by wind loads and gravity loads in a high-rise building.  A shear wall system joins solid structures that remain constant from floor to floor to add strength and stability in a tall building. However, shear wall construction inhibits the design of the foyer or lobby of a building. To achieve an open, inviting space, structural engineers often must use a combination of other support systems to allow for the desired design of the building.

Transfer beams are often used in conjunction with a shear wall system in commercial and high-rise buildings. Transfer beams are designed to transfer the load from the shear walls to the lower frame of the structure. This combination of transfer beams and shear wall supports has proven reliable, even in high winds and during an earthquake.

Beam design and structural design in commercial and high-rise buildings can utilize many different design techniques to achieve the desired height and visual attractiveness specified by the architect and owner. Beam design and structural design in commercial and high-rise buildings is an ever-evolving process.

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Types of Beam Design

Types of Beam Designs

There are many different types of beam designs and materials to choose from when designing a structure. Engineers can choose from various shapes, sizes, construction materials, and construction techniques. Deciding on the proper beam design for a particular structure can be a complicated process. Structural engineers and builders have many different beam designs and materials to choose from when attempting to create a sound structural design.

Cantilever Beams

Cantilever beam designs create a suspended effect. These beams allow the creation of a bay window, balconies, and some bridges. In cantilever beam designs, the weight load is distributed back into the main beams of the structure, allowing a portion of the structure to extend beyond the supported perimeters of the structure’s foundation.

Steel I Beam

Steel I beams are very popular choice in construction. The I beam is shaped like a capital I also know as a W shape. The I beam design is the most efficient use of structural steel since it moves the bulk of the steel into the portions of the beam actually resisting the loads. The I beam design is the most common foundational beam design found in commercial structures but can be used in Residential design.
Flitch Beam

Flitch beam designs are composite beams made from layering steel and wood to create a lightweight beam with adequate strength. The addition of wood elements allows the beams to be nailed to existing wooden structures.  Flitch beams are less expensive than solid steel beam designs. They are used to support heavy vertical loads while maintaining a strict construction budget.  Flitch beams are also very useful when adding additional load carrying capacity to an existing beam.
Hip Beam Designs

Hip beam designs are popular in roofing designs. A hip beam provides support for other load bearing beams branching off at symmetrical angles. This design is often used in residential construction.
Beam Materials

The various types of beams may be constructed of various materials as well as a mixture of shapes and sizes. Some beams are made of pre-stressed concrete, poured concrete, iron, wood, glulams, and other composite materials.
Beam designs vary so greatly that making the correct choice when designing a structure can be challenging. Structural engineering software can help take the guesswork out of the design process. Structural engineering software can also help an engineer decide if the desired beam designs are appropriate for the structure.

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Structural Beam Design Software

Structural beam design software is a builder’s best friend when planning a new structure. Structural beam design software helps eliminate potential structural failures and design flaws that may not be noticed until after construction has begun.

Beam design can be a complicated process. An experienced builder may know which type of beam is used to achieve a desired visual style of a structure, but is that beam able to support the load of the structure adequately? Does it leave open the possibility of expansion of the structure later on?  Is there a cheaper beam that would be adequate for the design of the structure?

Structural Beam Design Software

Structural beam design software allows a structural engineer, contractor or homeowner to design structural elements with performing of the mathematical equations required to design such elements.  Often, once faced with the design on a computer screen, necessary and desired changes become apparent and are easily remedied.

Bending and shearing stresses play an important role in choosing a beam design.  A top-quality structural beam design software program also calculates possibilities in the given beam design by using these values and comparing them to known structural engineering values to ensure structural integrity.

Structural beam design software will also take into consideration the stiffness, strength and size of the desired beam. It then calculates the potential weight-bearing load of the designed beam. Calculations based on the desired qualities reveal all viable beam design possibilities. Calculations can also be made that show the cost effectiveness of each beam design option.

The structural beam design software also provides a list of possible beam materials to help provide a stable structure without exceeding the given construction budget. Do you need a solid beam, or is a hollow beam a viable option? Do you need an I-beam design or a rectangular beam? Structural beam design software can help you sort out all the options.

Structural beam design software is a wise investment for any structural engineer, building contractor, or individual building a new home construction. It eliminates potential mistakes in the design of the structure, as well as ensures that structural integrity is maintained during last minute changes in building plans. Not all structural beam design software is top-quality. Be sure to research the features offered by a structural beam design software program including the support available with the program before selecting a structural beam design software package.

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Elements and Examples of Beam Design

The elements of beam design is a topic of great interest for structural engineers and contractors. Beam design is integral in the design and construction of a structure. Most structural beams are comprised of wood, steel or concrete. Each of these construction materials reacts differently under the stress of a load. Each also has its own unique advantages.

Elements and Examples of Beam Design: Concrete Beams

Concrete beams are most often seen in commercial construction, such as in the erection of multi-level parking decks, hospitals, and large hotels. Concrete beams are also commonly used as bridge and highway supports.  Some concrete beams are used in conjunction with steel beams to provide added strength. Newer concrete beams may also contain a hybrid material of traditional concrete mixed with Glass Fiber Reinforced Polymer (GFRP) or Carbon FRP.

Concrete is a strong building material, but it is susceptible to water damage and cracking.  Iron bars are often included in the beams to add strength and stability over areas prone to greater stress. Concrete beams area also desirable for their ability to absorb sound and vibration.

Elements and Examples of Beam Design: Steel Beams

One very common type of steel beam is the I-beam. These I shaped beam are strong and moderately affordable. Steel beams are capable of supporting heavy loads without experiencing great amounts of deflection by distributing the load of the structure over the flange of the beam. Steel beams may be treated to prohibit corrosion and oxidation, especially when used near or under water, such as in bridge construction.

Elements and Examples of Beam Design: Wood Beams

Wood beams are common in residential structures. Wood beams may be notched or jointed together for added strength. Wood beams are inexpensive and easy to alter to a builder’s specifications. However, they are also susceptible to rot and insect infestation.  Specially treated wood beams are now available that resist decomposition, moisture and insects, making them an attractive choice in beam materials for most homeowners.

Elements and Examples of Beam Design: Flitch Beams

Flitch beams are specially constructed beams that join a steel plate with adjacent wood panels to form one composite structural beam. These flitch beams are strong, yet less expensive and lighter than solid steel beams.  The construction of a flitch beam results in a reduction of the overall size of the beam, and the wooden exterior also allows the builder to nail the beam to other existing wooden structures in the home.

Elements and examples of beam designs are plentiful. Beam design and selection are an important part of the construction process and the wide variety of beams to choose from allow a builder to meet the needs of each project more easily.

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StruCalc Diagrams

Loading Diagram

The loading diagram is perfect for all of those teachers that wanted to see a free body diagram.  The loading diagram is a visual representation of the loading on the beam being designed.  Below the loading diagram there is also a summary of the various loads on the beam.  This is available in any of the beam design modules, but excludes the footing and column design modules.

 StruCalc Loading Diagram

The loading diagram above shows all of the different loads available:

  • point loads (in green)
  • uniform loads (shown on the center span)
  • beam self weight loads (shown on the left span)
  • trapezoidal loads (rectangular, trapezoidal, triangular; shown in red)

It also shows the reactions as determined by the pin setup you choose in the design mode. The loads are all scaled relative to each other’s magnitude. You can visually see that the left span TR1 load is twice that of both the center span TR1 and TR2 loads. Also it is possible to see that P3 is three times the magnitude of P1.

Shear/Moment/Deflection Diagrams

StruCalc also provides the shear, moment, and deflection diagrams (VMD Diagrams).  The diagrams are available for all possible loading conditions along all the spans of the beam.  StruCalc will automatically show the controlling shear, moment, and deflection, but by typing in a location and hitting calculate the shear, moment, and deflection values will be displayed.  This is available in any of the beam design modules but also excludes the footing and column design modules.

Strucalc VMD Diagram

View All StruCalc Features

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Flitch Beam Bolting

In a separate article entitled “Accurate Flitch Beam Design Made Easier with Software” there was an allusion to the difficulty associated with designing the connection between the solid sawn members and the steel members of a flitch beam.  In this article there will be a more in depth discussion on the methodology for attaching the different materials of a flitch beam so that all the materials act as one solid member.

Flitch beams must be connected together to appropriately transfer loads to the wood and steel portions of the beam in proportion to the relative stiffness of each material.  Most structural engineering software packages don’t provide this calculation; two sample methods are provided below for determining this connection.

Empirical Method

The first method is an empirical method, which is purely based on what has worked well in the past.  An example of a regular bolting pattern might be 1/2 inch diameter or 5/8 inch diameter bolts spaced 16 inches on center.  Stagger the bolts and make sure the bolts are placed a minimum of 2 1/2 inches from the edge of the beam.

Rational Method

The alternative to the empirical method is the rational method.  Using the rational method the load transfer between the steel and wood members is actually calculated.  The first step in the rational method is determining the percentage of load that is carried by both the steel and wood portions of the beam.  If structural engineering software was used to size the flitch beam then somewhere within the software there should be a display of the load transfer percentages.  If the flitch beam was sized by hand, then the load transfer percentages can be determined from the modular ratio that was calculated.  The load carried by the steel plate can then be determined by multiplying the percentage of load carried by the steel plate by the total load on the beam.  After the load has been determined bolts can then be sized by using tables found in the National Design Specification.

Example Calculation

 Flitch Beam Bolting

Now, determine capacity of 5/8 inch diameter bolts for loads traveling perpendicular to the grain of the wood.  For simplicity, use table 11B of the National Design Specification.  This is a table for single shear bolt capacities.  This is conservative since the flitch beam being sized actually has bolts in double shear.  Higher values can be calculated using the six yield equations.

 Flitch Beam Bolting Bolt

End bolts required to transfer steel plate load to wood members for bearing are required unless the steel plate bears on a steel bearing plate.

Flitch Beam Bolting Number of Bolts

Final Considerations

This is just one example of how to design the bolting for a flitch beam; there are certainly other valid methods and assumptions that will provide an adequate design.  When doing any kind of beam design, especially a flitch beam using structural design software will greatly ease the entire process of calculating adequacy.  There are several different engineering design software packages available for beams, columns, or foundation design.  StruCalc, Enercalc, Risa, and BeamChek are all examples of such software.

James DiNardo, P.E.
Josh Parker, E.I.T.
Cascade Design Group

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Flitch Beam Design & Software

Accurate Flitch Beam Design Made Easier with Software

Flitch beam design software is a useful tool for architects, engineers, designers, and builders. Flitch beams are a common type of composite construction. Composite construction materials are formed by combining two or more materials in a way that allows them to function as a single component structurally. Flitch beams are created by layering wood beams with steel plates or plywood in order to form a wider, lighter structural beam. Bolts hold the layered components together to form a single unit.

These advantages make flitch beams a desirable and attractive choice in light frame construction projects:

  • they can support heavier loads over longer distances
  • are thinner than solid wood or steel beams with similar load-bearing qualities
  • can be nailed to other components of wood structures during construction
  • are much lighter than solid beams.

Using computer software to design a flitch beam can greatly improve the cost effectiveness of a project by allowing for a more exact and efficient design.  Software packages precisely calculate the needed thickness, depth, and length of each beam much easier than any kind of hand calculation.

Utilizing flitch beam design software eliminates the possibility of using beams that are too thick or too closely spaced together.  This can drastically reduce construction costs by allowing each beam to be more fully utilized to its capacity.

One of the more difficult calculations associated with a flitch beam is that of the Deflection the beam will undergo.  Software packages will carefully calculate the deflection of flitch beams.  Properly constructed flitch beams ensure that all of the components deflect by exactly the same value. The relative stiffness value of steel and wood is vastly different.  When used correctly, structural analysis software will accurately determine the proper interaction of multiple materials.

Bolt size and Spacing in the construction of flitch beams is crucial. A separate article will briefly discuss a simple way of determining the bolt spacing for a flitch beam.

Flitch beam design software is a must-have tool for the careful architect, engineer, or designer.

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