Advances in Structural Engineering: How AI is Changing It

Advances in structural engineering have advanced the construction industry significantly over the past few decades – and the evolution of technology has disrupted the industry, particularly when it comes to the use of Artificial Intelligence (AI). Today’s structural engineers must have a greater understanding of how AI works to stay up-to-date with the latest technologies.

The use of AI in structural engineering is not a new concept – it has been used in the industry for many years. However, the application of AI has become more widespread in recent years, as the technology has become more sophisticated. AI is being used to create more efficient and accurate designs, optimize construction processes, and predict and prevent structural failures.

There are many benefits to using AI in structural engineering. By automating the design process, engineers can focus on more creative and innovative tasks. AI also can spot errors and identify potential problems, which can save time and money. In addition, AI can help to improve communication between engineers and other professionals, such as architects and contractors.

AI offers convenient and efficient ways of designing new structures without incurring the expense of errors that may arise from manual calculations.

Although AI offers many benefits, some challenges need to be addressed. For example, as AI becomes more involved in the design process, there is a risk that human expertise will be replaced by machines. This could lead to a loss of jobs and a decline in the quality of designs. In addition, AI is still in the early stages of development and there are some concerns about its reliability.

Overall, AI is having a positive impact on the field of structural engineering. It is important for engineers to keep up-to-date with the latest developments in AI so that they can take advantage of the benefits it offers.

Future applications of AI will likely include the development of software that can assist in several aspects of structural design.

Application of Artificial Intelligence in Structural Engineering

As discussed, there is a variety of services connected with advances in structural engineering. Let’s discuss how AI connects in the process;

Structural Health Monitoring

The process of carrying out a damage detection and characterization technique for designed buildings and structures is known as structural health monitoring. It covers the processes of developing statistical models, extracting data features, evaluating operations, and tracking system health. The assessment of post-earthquake structural integrity, the monitoring of structures impacted by external factors, the decline in construction and rise in maintenance requirements, the transition to performance-based design philosophy, the performance enhancement of an existing structure, and feedback loops to improve the future design based on experience are some of the objectives of structural health monitoring.

Construction Management

The management of a construction project, starting with the initial design phase and ending with the handover to the client, is what the construction management system entails. The process of fusing an ultimately acceptable result depends heavily on the initial model design. The use of neural networks predicts a better initial design, which covers several important areas in the construction sector, including the calculation and determination of concrete mix grade, load calculations, the determination of the tensile reinforcement and depth of the beam, and the calculation of moment capacity. Artificial intelligence is used to generate plans at various project stages, including the explanation of the steps taken during project management.

Quality Assurance

One of the most crucial factors in the construction of a structure is “quality.” By using AI-based software, it is possible to maximize the materials’ efficacy and efficiency. Drones can be used to capture photographs of the site or structure from any angle the engineer desires. Using technologies like image recognition (IR), the engineer can then detect cracks or dangerous locations and compare the results with other technical drawings or sketches. AI can also be used to produce 3-D models of buildings, which are then compared to the original models to look for flaws.

Optimization of Designs

Contractors that deal with pre-given input data and supervised learning software employ AI-based solutions. Many architectural data points are inputted, along with their solutions for various job designs and suggestions for any odds or uncertainties. The requirements for various locations vary from one location to another. Source

Do I Need A Home Inspector AND A Structural Engineer To Look At A House Before Purchase?

Yes and a resounding yes- if the home inspector discovers glaring structural issues...

First, having a home inspector make a general inspection of the property.  A home inspector should be the first professional you hire when considering a house for purchase. Home inspectors will evaluate the overall serviceability of the home including the electrical, plumbing and HVAC systems. Their assessment is general in nature and if they find a potential problem with home’s foundation, roof or framing systems they will recommend that a structural engineer be hired to perform a more detailed assessment.

In the event a home inspector suspects a structural issue or major serviceability problem- a structural engineer should always be consulted. It should be noted, even minor structural problems can fly under the radar. That is why it is our recommendation to hire a  licensed, structural engineer when considering the purchase of a home no matter the home inspection results. The amount of money on the line and the investment one commits to when buying a house, make hiring an engineer critical to avoid major problems down the road. 

The Benefits of Hiring a Structural Engineer after the Home Inspection-

Although a home inspector is the first line of defense and first inspection, its important to remember that a home inspector looks over the entire property- everything from the light switches to the toilet flushing properly. They are critical to the home buying process but their education and experience is limited. To become a certified home inspector , 5-8 months of study and a certification test is required. 

Conversely, a structural engineer must graduate with a four year degree and  then they can they take the test to become an engineer in training (EIT) . After passing the EIT exam one must study under a licensed professional engineer for four (4) years before they are eligible to sit for the test to become licensed, professional engineer. Engineering licensing is regulated by the department of state in each of 50 US states. 

Buildings and houses are made up of complex systems. The building envelope or “skin” of a s house  is composed of the walls, exterior, windows and roof. If any part of the building envelope is compromised, a home buyer may  be forced to spend thousands of dollars to make it right. Water infiltration can be devastating a bad building envelope is often the culprit.

The same is true for a house’s foundation and walls. These are “the feet and legs” Often times, foundation issues are covered up and concealed by finish work or furniture/equipment common to storage areas such as the basement. 

Those individuals who choose to skip an engineering evaluation,  are taking a chance that high dollar repair items may be missed- such as a compromised foundation, building envelope or roof system.

How Much Does A Home Inspection and Structural Engineering Inspection Cost?

The cost to hire a home inspector is usually between $300-600. A structural engineering inspection is usually between $600-900 for a standard 1k-3k square foot home.  When comparing the amount of money the average house will cost, these fees are minimal and dollars well spent to prevent future problems after the purchase.

A foundation problem can cost anywhere from $1,000 to $50,000 to fix. When assessing a potential property for purchase, it is critical to discover these issues prior to signing a contract. Keep in mind, houses have a past and skeletons in their closets too! If a potential buyer doesn’t uncover these “ghosts” before the purchase, they are inheriting all of these past issues and the headaches that come with a “problem property”.  Don’t take the chance- hire an engineer after your home inspection. No one wants a money pit! Source

3 Ways a Structural Engineer Can Help With Your Custom Home

When a custom home is in the works of being built, there’s an entire team of people you need to look at hiring. These people include architects, interior and exterior designers, engineers, contractors for general work and many more. Most people don’t think about contacting structural engineering companies first, but the truth is finding a good structural engineer should be a top priority. No matter how good a home looks on the outside, it’s only as good as the structural engineer who designed the plans from the foundation all the way to the top of the chimney. 

Here are the main ways a structural engineer is important when you’re looking to build a custom home;

1.) Structural Safety

Every structural engineering company prioritizes safety in all aspects of the work they do. When evaluating the location of a custom home, a structural engineer will look at factors like the soil, the climate in the area, what major weather events typically occur, the seismic activity and more. Sometimes it’s simply not safe to build a home with the exact orientation the homeowner wants, which is exactly why it’s important to take the advice of structural engineering experts.

2.) Use The Right Building Materials

While safety is the first priority when building any custom home, structural engineers also want to bring a homeowner’s vision to life as much as possible. This can include wood framing, bamboo, masonry, steel or any other materials. Many times a structural engineer will get an idea of the vision the homeowner has and then go to work designing the home based on that. If it’s simply not possible or safe to build it exactly like the homeowner desires, then they will inform them accordingly. There are many different factors that go into the building materials used for any custom home, and the best structural engineers will still make the custom home look as close to the homeowner’s vision as possible.

3.) Efficient Designing

Most people don’t think about contacting a structural engineer when designing their home. This is typically done by an architect. However, structural engineers put together plans for the design that takes into consideration the foundation, roof, framing and overall structural integrity to be able to support the desired designs. Architects and other contractors rely on structural engineers for this information, which is why they are typically the first experts needed when designing a custom home. Source

Guide on How to Plan Your ADU

This guide is intended to assist you in determining the feasibility of adding an ADU to your property and will help answer your questions of “How large of an ADU can I add?”, “Where on my property will an ADU fit?”, and many more. The intent with this guide is to be a self-service guide; however, a design professional can be consulted during this early stage as well to help you through this process. This guide poses questions to be considered and checked with your local jurisdictional requirements. You should contact your local building, planning, and environmental health departments to receive their individual requirements.

Each jurisdiction will vary in requirements and may have additional planning requirements to consider beyond this guide. It is important to review the date of your local jurisdiction’s ADU zoning requirements. Many jurisdictions have not modified their requirements to meet the State’s requirements that became effective January 1, 2020. If the local jurisdiction’s requirements are not compliant with the State requirements, then the State requirements supersede.

You can find information about your local jurisdiction by searching online for the name of your County, City, or Town and “Planning Department”.

Step 1 – Determine area allowed for ADU

Here you will want to mark out the minimum setbacks and minimum separations between the ADU and other structures on your property (minimum separations and setbacks can be determined by speaking with your local jurisdiction, rear and side setback minimums are 4’ per State law, however local jurisdictions may reduce this minimum). Once these are marked out, you can measure the allowable footprint of the ADU. This will allow you to calculate the size limitations of the ADU for the property.

Other features to mark out will include the sewer line or septic tanks and leach-field, water line (and well if applicable), utility lines, easements, driveway(s), parking areas, etc and their respective setbacks.

Items to note:

 Fire separation systems will be required if certain setbacks are not maintained. These will increase construction costs and will drive certain design features. If possible, maintaining 5’ between the ADU and property lines will help reduce costs.

Property boundary surveys may be required when constructing close to property lines. You will need to check with your local jurisdictional requirements to determine if a survey is required.

Completing this step will also create the foundation for the site plan, which will be required as part of the submittal package.

Step 2 – Determine jurisdictional planning requirements

What is the maximum height allowed by your jurisdiction? State law requires the maximum height to be at least 16’.

Is your lot in a flood zone? Can the floor of the ADU be located above the minimum flood elevation requirements and still meet the maximum height requirements?

Must the ADU be of similar roof lines, shapes, material finishes, etc as the primary residence? Is a ministerial permit required?

Can parking be accommodated? 1 off-street parking space may be required per ADU. Consider the path of travel from parking areas to the ADU (can your standard of privacy be maintained). What is the distance of this path of travel? Additional requirements may apply.

What is the distance to the nearest fire hydrant?

What dwellings already exist on your property? State law allows for 1 primary residence, 1 ADU, and 1 junior ADU.

Step 3 – Determine environmental factors

Will the placement of your ADU require the removal of trees? In some jurisdictions, the removal of trees may be limited per jurisdictional requirements.

If your property is on a septic system many jurisdictions will require a separate septic tank be installed for the ADU, and may allow the existing leach-field to be utilized and expanded. Is there space for the expansion of the existing leach-field? Or will a new leach-field for the ADU be required, and is there room on the property for this?

Depending on the location of the ADU in relation to property lines and other structures, additional drainage features may be required. For example, the ground is typically graded away from foundations for the first 6’. If the property line and/or other structures impede this 6’, other measures will be required.

Item to note:

 In certain circumstances, buildings may be placed over waterlines and wastewater lines. Buildings may not be placed over septic tanks or active leach-fields.

Step 4 – Determine the maximum footprint of your desired ADU

What size ADU would you prefer? This number must be equal to or less than the size determined in step 1. A few key numbers to remember:

• 1200 sqft of conditioned space is the maximum allowed by State law
• 150 sqft of conditioned space is the minimum size required

If you are less than 750 sqft of conditioned space, no impact fees will be assessed.

Local jurisdictions must allow up to 800 sqft to be constructed regardless of lot coverage requirements. Above 800 sqft may be subject to limitations of lot size, lot coverage, lot coverage specifically around the ADU, bedroom counts, etc.

This 800 sqft is not defined to one type of measurement. Some jurisdictions will allow up to 800 sqft of conditioned, while others will allow up to 800 sqft of footprint, and others yet will count some covered porches, depending on configuration. The way the local jurisdiction measures this must be determined during this step if lot coverage may be an issue.

Does your jurisdiction limit the size of covered porches, attached carports/garages, decks?

1 bedroom units may be limited to 850 sqft, 2 bedroom units may be limited to 1000 sqft.

Step 5 – Determine utility requirements

In step 1, you marked out existing utilities. How will these utilities be affected by the ADU? Will wastewater from the ADU be able to drain properly to the septic system or sewer line?

• What is the flow of your fresh water supply? Is this sufficient to provide water to an additional unit? Or will a larger line be required? If your property is supplied by a well, does the well produce enough water flow for another unit?
• What is the distance of new water line, sewer line, electrical line, gas line, etc required to be installed? What are the lead times and requirements posed by your local utility companies to make these changes?

Step 6 – Determine if grading will be required

Is the lot relatively flat? ADUs can extend 50’ or more in one direction, or as little as 10’ or less. ADU placement with the slope of the lot can help reduce grading, but may not entirely negate it. Depending on your jurisdiction, a grading permit may be required. You can roughly estimate the amount of material needed to be graded by multiplying the average depth of grading by the total footprint of the unit. If this number is close to, or exceeds the local jurisdiction requirements, a grading plan may be required.

Step 7 – Repeat Steps 4-6 (if required)

If you find the costs associated with utilities and/or grading are becoming too high, you may want to consider reducing the size or reconfiguring the shape of your ADU by repeating steps 4-6.

Step 8 – Begin the design phase of your ADU

You are finally ready to begin designing your ADU. This can take place in many forms. You may be ready to sit down with a design professional and work through various layouts, or you may want to sketch some ideas out yourself. Either way, you will now know your building limitations (height, allowable conditioned space, allowable footprint, and allowable size of covered porches and attached garages, etc.) Here at Jackson & Sands Engineering, Inc., we have a number of predeveloped ADUs that may fit all your design needs. Utilizing a pre developed design can help save you both time and thousands of dollars in design costs. Source

How to Build a Concrete Block Retaining Wall

Concrete block retaining walls are ideal for holding back the soil after digging into a slope for a pathway, patio, or landscaping project. Concrete block retaining walls are generally the same as freestanding block walls but with a few crucial differences.

A retaining wall must provide a way to release the water that builds up in the slope behind it. Without a pressure-relief system, the weight of the water in the soil would crack or even buckle the wall. Weep holes, lengths of ¾-inch pipe inserted along the top of the first course, escort some of the water out. The other part of the system is a plastic drainpipe covered with gravel. As water accumulates behind the wall, it percolates through the gravel into the drainpipe, which carries it off safely.

Concrete block retaining walls must be stronger than freestanding walls. Insert rebar in the footing when you pour it; this should be done every three blocks or at intervals specified by your local codes. As the last step, fill the cores around the rebar with mortar from the bottom to the top.

Expect to spend 20-36 hours building a 3x10-foot concrete block retaining wall. Before you begin, you'll need to design the layout and pour the footing.

Step 1: Build and Prep Footing

Lay out the wall and excavate the slope and the footing trench. Build the footing and insert rebar into the wet concrete at intervals corresponding to the cores in the blocks. Prepare the footing, spread mortar, and build leads, sliding the block over the rebar as needed.

Step 2: Insert Weep Holes

As you lay the second course of the concrete block retaining wall, insert weep holes (¾-inch pipe) into the mortar every third block. Chip off a small recess in the block and trowel a mortar bed for the pipe, sloping it slightly toward the front. Then, chip out a recess on the next block, butter the ears, and set the block.

Step 3: Scrape Off Excess Mortar

Stop occasionally to check the mortar. When it begins to set up slightly, scrape off the excess with an upswing of the edge of the trowel. Do not plug the weep holes with excess mortar as you remove it.

Step 4: Lay Landscape Fabric

After you've laid at least two courses, spread landscape fabric on the soil behind the base of the concrete block retaining wall, temporarily laying the excess over the grass on the slope. Lay rocks on the fabric to hold it while you work. Backfill the wall with gravel between the rear of the wall and the slope, laying perforated drainpipe on the gravel bed level with the top of the first course. Face the holes down.

Step 5: Cover Drainpipe

Shovel more gravel on top of the drainpipe. Backfill with additional gravel as you add courses to the wall. Fold the landscape fabric over the top of the gravel fill, and backfill with soil. Replace the sod.

Step 6: Fill with Mortar

When you reach the finished height of the concrete-block retaining wall, fill those cores containing rebar to the top with mortar. Mix the fill mortar slightly wetter than what you'd use for joints. Smooth the top with a trowel. Spread additional mortar, and lay cap block to finish the wall. Source

7 Types of Bridges Every Engineer Should Know About

There are many different types of bridges, and each has its own advantages and disadvantages.

If you are an engineering contractor or civil engineer intending to work on bridge projects, here is a refresher of the basic principles behind each type. If not here is a list of the different types of bridges there are.

The Seven Main Types of Bridges

1.) Arch Bridges

Arch types of bridges use one or more arches as the main structural component, with the arches positioned beneath the deck. This method dates back many thousands of years, with stone and brick being the most commonly used materials. However, in modern times you will see arch bridges constructed from concrete.

Whatever material is used the principle remains the same: An arch bridge uses compression – downward pressure from the deck travels laterally towards the keystone and to the supporting structures at each end of the bridge (the abutments).

Advantages of Arch Bridges

• High levels of strength and resistance (many Roman bridges still exist).
• Adapts to local environmental conditions well.
• Greater span compared to beam bridges (though less span than cantilever and suspension types).
• Can be constructed from many different materials; stone, brick, concrete, iron, and steel.

Disadvantages of Arch Bridges

• Creating a long span length requires more arches.
• Time-consuming to construct and maintain.
• Requires strong side support to complete a successful span.
• Requires considerable expertise to build.

Examples of Arch Bridges

• New River Gorge Bridge, Fayette County, West Virginia, USA.
• Rialto Bridge, Venice, Italy.
• Stari Most Bridge, Mostar, Bosnia and Herzegovina.

2.) Beam Bridges

Beam bridges are the simplest type of bridge. In its most basic form, all that is needed is a crossbeam long enough to cover the span, and support from abutments under each end. To achieve a longer continuous span, (e.g., over 250 ft (80 m), piers need to be added to provide extra support. When doing this it means you create a series of bridges joined together.

A beam bridge may include several beams running in parallel to support the deck above. This is often referred to as a simply supported structure.

Advantages of The Beam Type of Bridge

• Simplicity and quick construction.
• Inexpensive (if no piers needed).
• Modules can be prefabricated away from the bridge location.
• Versatile – can be used in many locations.
• Multiple types of material can be used.

Disadvantages of Beam Bridges

• Limited span length between supporting structures.
• They can start to sag as they age (Weight limits are sometimes needed).
• Poor aesthetics.
• Costs are affected by fluctuations in steel prices.
• Maintenance and painting costs of steel bridges is expensive and time-consuming.

Examples of Beam Bridges

• Donghai Bridge: connects Pudong New area in Shanghai to Yangsang Deep Water Port in Zhejiang. 20.2 miles in length from one end to the other!
• Manchac Swamp Bridge, Louisiana, USA.
• Dhola Sadiya Bridge, over the Lohit River in India.

3.) Cantilever Bridges

If you aren’t familiar with the cantilever principle, think of a diving board that is supported at just one end. A cantilever bridge is built using pillars securely anchored to the ground. The structure is then constructed outwards from each pillar with the horizontal beam often supported using diagonal bracing.

A cantilever bridge can be made using different materials, such as structural steel, or box girders of prestressed concrete for larger bridges that carry road or rail traffic.

Advantages of Cantilever Bridges

• A good method for creating long spans.
• Support is required only on one side of each cantilever.
• Suitable for deep rocky valleys and flood-prone areas where supporting structures cannot be built.
• Little or no disruption to traffic underneath the bridge.
• On bridges with multiple spans, the cantilevers can be built simultaneously to reduce time.

Disadvantages of Cantilever Bridges

• Complex to construct and maintain.
• Requires a heavy structure – so more material needed drives up the cost.
• Not suitable for excessive climate conditions or earthquake-prone areas.
• Experiences a high amount of tension during the construction (aka Negative moment).
• Stability relies on balancing compressive and tensile forces.

Examples of Cantilever Bridges

• Forth Bridge, Scotland, UK.
• Quebec Bridge, Quebec, Canada.
• Minato Bridge, Osaka, Japan.

4.) Cable-Stayed Bridges

The cable-stayed bridge dates back to the 16th century and remains a popular design for spans greater than those of cantilever bridges – but shorter than the longest suspension bridges.

This design uses deck cables connected to one or more vertical columns, towers, or pylons which can be connected in either a fan or harp configuration. Although the deck relies on the cables for support, this method should not be confused with the suspension bridge that uses vertical cables between the deck and the main support cable.

The most common build materials used in cable-stayed bridges are steel or concrete pylons, post-tensioned concrete box girders, and steel rope.

Advantages of Cable-Stayed Bridges

• Fast construction time compared to other bridge types.
• More rigid than suspension bridges.
• Cost-effective.
• Can be aesthetically pleasing.
• Multiple design options: (e.g., side-spar, cantilever-spar, multiple-span, cradle-system designs).

Disadvantages of Cable-Stayed Bridges

• Suitable for short to medium distances (Shorter span than suspension bridges).
• Difficult to access in some areas, which means higher-than-average costs of maintenance.
• Cables can be prone to corrosion and high levels of fatigue.
• Easier to vandalize (by cutting cables).
• Not suitable for excessive climate conditions or earthquake-prone areas.

Examples of Cable-Stayed Bridges

• Millau Bridge, Occitanie, France.
• Queensferry Bridge, Scotland, UK.
• Jiaxing-Shaoxing Sea Bridge (Jiashao Bridge), China.

5.) Suspension Bridges

The principle of a suspension bridge is not new – early designs simply used rope and wooden planks. Today, they are a popular design for long road bridges – thanks to the ability to create large spans across broad channels. Probably the most famous of all is the Golden Gate Bridge in San Francisco, US.

A suspension bridge uses vertical towers or pylons constructed from steel or reinforced concrete.

Attached Between the pylons are the main supporting cables. These cables are made from galvanized steel wire, and including their casing, can measure as much as 36 3/8 in (0.92 m) diameter. The Golden Gate suspension bridge is arguably the world’s most famous suspension bridge and is one of the most photographed. The American Society of Civil Engineers voted this as one of the Seven Wonders of the Modern World.

Advantages of Suspension Bridges

• The best bridge type for creating the longest spans with minimum piers.
• Regarded by many as aesthetically pleasing – creating a landmark for the community.
• The waterway can be left open while the bridge is under construction – (almost all of the work takes place on the top of the bridge).
• Flexibility – design allows for deck sections to be replaced.
• Can be built with a high deck, allowing plenty of clearance for passing ships.

Disadvantages of a Suspension Bridge

• Not as robust as some bridge types.
• A combination of vertical pressures and extreme side wind speeds can lead to a failure of the span.
• High winds can cause a suspension bridge to start vibrating.
• They can struggle to support focused heavy weights (e.g., trains).
• Failure of just one cable can be enough to cause the entire bridge to collapse.
• Access below the deck is difficult during construction and maintenance.
• Some suspension bridges require extensive foundation work if the ground is soft.

Examples of Suspension Bridges

• 1915 Çanakkale Bridge, Turkey.
• Humber Bridge, England, UK.
• Golden Gate Bridge Suspension Bridge, San Francisco, US.

6.) Tied-Arch Bridges

A tied-arch or bowstring bridge uses features seen in both a suspension bridge and an arched bridge. However, unlike a traditional arched bridge, the arch is positioned above the deck and uses vertical cables attached to support the deck.

This arch (or bow) uses the tension of its vertical cables, together with the compression of the arch, to support the load – keeping the bridge very stable.

Advantages of Tied-Arch Bridges

• Very strong.
• Less force on abutments.
• Can be built off-site and transported into place.

Disadvantages of Tied-Arch Bridges

• Regular maintenance is required to ensure the stability of the hangers and arch.
• If one hanger breaks the entire structure can be adversely affected.
• The size of each span is limited as compared with suspension bridges
• More expensive to build as compared with other types of bridges the same length.

Examples of Tied Arch Bridges

• Fort Pitt Bridge, Pittsburgh, Pennsylvania, USA.
• Clyde Arch Bridge, Glasgow, UK.
• Puente de la Barqueta, Seville, Spain.

7.) Truss Bridges 

There are many different configurations of a truss bridge, but you will notice they all use triangular sections typically bound together by welded or riveted joints. The trusses are constructed vertically and horizontally which absorb tension and compression. The end result is a structure and decking area capable of withstanding relatively strong winds.

The truss design is reasonably inexpensive and has been around for a long time. In the early days during the 19th century, most were built of wood, before later shifting to iron and steel.

Advantages of Truss Bridges

• The strongest type of bridge.
• Can be built off-site and quickly installed on location.
• Lighter than other bridge types.
• Economical.
• Withstands extreme weather conditions.
• Versatile – able to carry its roadway above (deck truss), along the middle (through truss), or on a lower truss sitting below the major structure.

Disadvantages of Truss Bridges

• Truss bridges require perfect construction to work. They must distribute weight evenly.
• Older truss bridges designed for light traffic can have a lower weight tolerance.
• Requires a lot of space. Interconnecting triangular components need to be large to bear and distribute heavy loads.
• There are width requirements in relation to span length to achieve the required strength
• Less attractive to look at compared to modern concrete bridges
• Requires architectural and engineering specialists – less use of general laborers and steelworkers.

Examples of Truss Bridges

• Tokyo Gate Bridge, Kōtō City, Japan.
• Astoria-Megler Bridge, Columbia River, USA.
• Quebec Bridge, Canada.

The 7 types of bridges covered above represent the main configurations, but there are many variations within each category and some interesting hybrid designs. Source

What Is a Gable Roof? 8 Styles to Know

A gable roof is a popular roof design that is used with most architectural styles. Not only are gable roofs beautiful, but they're easier to construct than other roof styles, such as hip roofs, mansard roofs, and gambrel roofs. Plus, the simple design sheds water easily and provides more attic space than most other roof styles. 

What Is a Gable Roof?

A gable roof is a roof style consisting of one horizontal ridge and two slopes that form a triangular shape. Because gable roofs are very simple, they're often accompanied by dormers, which rise vertically from the roof slopes to create more living space and architectural interest.

Variations of Gable Roofs

Within the larger genre of gable roofs are numerous variations. Some methods are commonly used across many home designs, while others are reserved for specific architectural styles.

Here are some popular types of gable roofs:

• Open Gable: The open gable is a standard gable roof consisting of two slopes meeting at one ridge to form a triangular roof. The gable's end is left open and the wall fills the space between the slopes.

• Box Gable: On a box gable, the gable's end is closed and the wall stops below the start of the gable. The finished triangular section gives the roof a more finished look.

• Front Gable: A front gable is a standard gable roof that jets out at the front entrance of the home.

• Gambrel: While often designated as a separate roof style altogether, a gambrel roof is technically a variation of a gable roof in which the sloping sides are broken into two pieces with different pitches.

• Saltbox Gable: A saltbox gable is one with an off-center peak, resulting in two slopes with differing lengths. The slopes can be the same pitch, which allows them to reach different wall levels by spanning different distances, or different pitches, which allows them to reach the same wall level over different distances.

• Dutch Gable: A Dutch gable is a hybrid roof style combining features of a hip roof and a gable roof. The lower portion of the roof is a hip roof and the upper portion is a gable roof.

• Shed Gable: A shed gable is often called a skillion or a lean-to. This design is defined by a single roof slope that's often standalone but can be attached to a building or another roof surface.

• Jerkinhead: A jerkinhead roof is a gable roof with a hipped portion near the peak. This hybrid style creates a unique aesthetic while offering a significant level of wind resistance over a standard gable roof.

Gable Roof: Pros and Cons

Gable roofs are undoubtedly the most popular style of roof in America. The reason for this? Gable roofs have many more advantages than disadvantages. Here are some pros and cons of gable roofs.

Pro: Attic Space

When compared to a hip roof, another popular roof style, gable roofs create far more usable attic space.

Pro: Easy to Build

A simple gable roof is the easiest type of roof to build, as it has a very simplistic frame.

Pro: Rain and Snow Resistance

A gable roof's simple two-slope design allows it to easily shed rain and snow, assuming the roof has the appropriate pitch for the given location. This is because gable roof design lacks an excess of ridges and valleys, which may create potential leak points.

Con: Poor Wind Resistance

While gable roofs are plenty strong, they aren't always the best pick for areas that see high winds or hurricanes. Hip roofs have superior wind resistance thanks to their aerodynamic design and strong frame design.

Pro: Design Possibilities

Gable roofs aren't limited in their design potential, making them popular choices for many architectural styles, from Bungalows to Colonials to Greek Revivals. On the other hand, hip roofs, gambrel roofs, mansard roofs, and other common roof styles tend to heavily alter a home's overall look.

Pro: Ventilation

The horizontal gable at the end of a gable roof creates an ideal spot for an attic vent. This is preferable, as gable vents are some of the best ways to vent an attic, over other options like ridge vents, roof turbines, and soffit vents. Source

Top Design Tips From ADU Owners

There’s a lot that goes into designing an ADU, particularly because they’re smaller than most houses, and are on the same plot as your home. 

Work With Your Small Space

Because you’re likely working with a smaller area than you’re used to, it’s important to be mindful about optimizing the space you do have. Kimberly says you should follow the classic construction rule of thumb when it comes to ADU floor plans and furniture: Measure twice and buy once.

“Each room and each area has to be both highly defined and uniquely accessible without being overly decorated or filled with furniture,” says Kimberly. “The last thing you want is a sofa that is too big for your living area, or a dining table that is too big for your dining area.”

Storage Is Key

In a small space with shifting uses, clever storage solutions are essential to a comfortable (and uncluttered) stay. Kimberly suggests taking advantage of vertical space by hanging shelves and hooks, incorporating multi-use furniture with storage, building closets and drawers into the ADU’s structure, and avoiding clutter at all cost.

Lean Into Lighting

Lighting is key to creating a comfortable, aesthetically pleasing ADU—and to making a small space feel less claustrophobic.

“Maximize the interior space by adding height and as many windows as you can afford, because sunlight makes a small space feel larger,” says Diana.

Windows, and the natural light they bring, are essential, but there are other creative ways to brighten up an ADU. Kimberly suggests mixing natural light with ambient and task lighting fixtures, and says that installing skylights above the bed and in the bathroom in her ADU really helped open up the space. 

If you don’t have the option to add more lights or windows, consider painting and decorating with light colors—an easy hack to make a space feel lighter and more spacious. Also, in a pinch, mirrors will reflect light around the ADU, giving the illusion of a larger space.

Offer Thoughtful Amenities

Whether you’re building an ADU for your family or for Airbnb guests, you’ll want to make sure to provide everything that your visitors need to feel comfortable, no matter how long their stay. Bathroom and kitchen amenities may seem obvious, but there are some things you won’t want to forget if you want to avoid trips back and forth from the main house—or out to the store.

Stocking the kitchen with pots, pans, utensils, and dishware makes a space feel like home, and adding counter space and modern appliances ensure your guests don’t have to leave the house to find a full meal. 

“Think about the kind of magical experience YOU would like to have, and then begin with the end in mind,” says Kimberly.

Diana also suggests implementing the amenities you might find in a luxury hotel room—a coffee bar, mini fridge, and fresh, white linens—to upgrade your guests’ stay. Plus, making sure your visitors have a comfortable place to work remotely is an added bonus in this work-from-everywhere era, says Isabelle, who owns an Airbnb ADU in Austin.

Take Advantage of Outdoor Space

One of the perks of bringing an ADU into your backyard is the built-in outdoor space that comes with it. A mini patio, balcony, or seating area adds more comfortable living space for guests, and can make a world of difference. Implementing outdoor lighting, too, will help you keep an eye on your space, and will make coming and going much easier for visitors.

Also, keep the garden in mind! Kimberly says that an outdoor plant display can quickly become an ADU’s best friend.

“Because the outdoor space is probably going to be small, don’t be afraid to go wild or experiment with your foliage options,” she says. “We use copious amounts of ferns, wild ivy, flowers, plants, and other things to give the small outdoor space a forest/tropical vibe.”

Don’t Forget About Privacy

Something ADU hopefuls often forget about is privacy—for guests and homeowners alike. Whether you install partition walls, small fences, gates, or doorways, creating a barrier between the ADU and your home will ensure that nobody intrudes upon anyone else’s space. 

“Think about how the ADU can fit into your backyard and how you will enter and exit—we really value having a separate private entrance to our backyard so that guests can come and go as they need,” says Diana.

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What Qualifies As An ADU In California?

An accessory dwelling unit, or ADU, is a separate living area on a property with a proposed or existing primary residence. ADUs, sometimes called granny flats or backyard cottages, are cost-effective housing options because homeowners can create new living spaces without buying property. Accessory dwelling units maximize space and expand housing options in existing neighborhoods.

An ADU is a versatile space that can be used as a home office, a guest house for family members to live or stay when they visit, or a rental property to earn passive income. California has relaxed ADU laws and streamlined the permit approval process to encourage building ADUs and creating more affordable housing.

ADU vs. JADU 

ADUs and junior accessory dwelling units (JADUs) are separate living spaces that fit into all kinds of neighborhoods, from suburban communities to city centers. There are a few types of ADUs, including detached, attached, and ADU conversions.

Detached ADUs are stand-alone units on the same lot as a proposed or existing primary dwelling. Attached ADUs connect to the main house and are generally added to the side or back of the house. Conversion ADUs, like garage conversions, involve transforming an existing space into a residence.

Unless there is a local ordinance that states otherwise, ADUs can be up to 1,200 square feet or 50% of the main home’s living area and must have their own kitchen and bathroom facilities. Depending on local regulations, ADUs may or may not need to include a parking spot.

Junior ADUs can be no more than 500 square feet and are allowed within the walls of a proposed or existing single-family residence. JADUs require an entrance separate from the main house and owner-occupancy of either the primary home or JADU. Junior ADUs do not need to include a parking space.

For fee purposes, JADUs are not considered new or separate housing, meaning no providers, including non-municipal providers, can charge fees for providing water, sewage, or power.

What’s the difference between an addition and an ADU in California?

Additions and ADUs add livable space to a property, but ADUs must meet different California building code requirements for a second dwelling unit.

Additions can be an extra bedroom, office, or game room within the primary residence. An ADU is an independent housing unit with a permanent kitchen and a minimum ¾ bathroom, including a toilet, sink, and shower. An ADU can be a room addition if it meets the requirements, but an addition isn’t an ADU.

Does an ADU increase property taxes in California? 

Building an ADU on your lot in California is developing your real estate and can increase your property value by up to 30 percent. As your property value increases, so will your property taxes.

California assessors treat ADUs like home additions and will complete a blended assessment. The assessment will only account for the new square footage; the assessor will not consider the existing home.

Your taxes will likely increase by 1 to 1.5 percent of the construction cost. So, if your ADU costs $250,000 to build, you might pay around $2,500 annually in additional property taxes.

ADU requirements in California

California ADU laws impose standard requirements for ADUs at the state level. Local governments may have zoning rules and adopt ordinances regulating ADUs. Understanding your municipality’s unique rules is essential before you start planning new construction.

Lot Size: There is no state minimum lot size requirement to build an ADU on your property, and local governments cannot impose minimum lot size requirements.

Unit Size:

• All types of ADUs must be at least 150 square feet.
• Detached ADUs can be a maximum size of 1,200 square feet unless there’s a local ordinance with a different size requirement.
• Attached ADUs can be a maximum of 50% of the primary dwelling’s living area or 1,200 square feet, whichever is smaller. Again, this is dependent on local ordinance.
• A one-bedroom ADU must be at least 850 square feet. A two-bedroom unit must be at least 1,000 square feet. Local agencies can adopt ordinances to set minimum and maximum unit sizes for ADUs so long as they meet these square footage requirements.

Bedrooms:

California state law does not allow a limit on the number of bedrooms in an ADU. Limiting the number of bedrooms can be considered discriminatory towards protected classes and impede the development of new ADUs. Local governments cannot adopt ordinances that impose bedroom limits for new ADUs. However, building code requirements still apply.

Amenities:

ADUs must have living, sleeping, and cooking provisions, including a permanent range with a stovetop and oven and at least a ¾ bathroom with a toilet, sink, and shower.

JADUs must have the same provisions, except they may share a bathroom with the primary house.

Height Limits

State ADU law does not impose a height limit on accessory units. Local governments can adopt ADU ordinances imposing height limits as long as the limit is no less than 16 feet for a single-story unit.

In conclusion, an ADU is a secondary dwelling unit with complete independent living facilities for one or more persons and generally takes three forms:

• Detached: The unit is separated from the primary residential structure
• Attached: The unit is attached to the primary residential structure
• Repurposed Existing Space: Space (e.g., master bedroom or garage) within the primary residence is converted into an independent living unit

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OSHA Standards for Construction and Workplace Safety

What is OSHA?

OSHA, the Occupational Safety and Health Administration, is a federal agency under the United States Department of Labor. It was established in 1970 with a primary mission: to ensure safe and healthy working conditions for employees across various industries. OSHA achieves this mission through the development and enforcement of workplace safety standards, outreach programs, and training initiatives.

OSHA’s Mission

OSHA’s core mission revolves around:

• Setting and enforcing safety and health standards.
• Providing training, outreach, education, and assistance.
• Conducting inspections to identify and rectify workplace hazards.

OSHA Standards for Construction

The construction industry is known for its dynamic nature and diverse range of tasks. OSHA recognizes these challenges and has implemented specific standards to address them. These standards encompass various aspects, including fall protection, electrical safety, and hazard communication.

Key OSHA Regulations for Construction

Some crucial OSHA standards for the construction industry include:

• Fall Protection (29 CFR 1926.501)
• Scaffolding (29 CFR 1926.451)
• Excavation and Trenching (29 CFR 1926.650)
• Electrical Wiring Methods (29 CFR 1926.405)
• Hazard Communication (29 CFR 1926.59)

OSHA Standards for General Industry

General industry encompasses a wide range of sectors, including manufacturing, healthcare, and warehousing. OSHA has tailored standards to ensure the safety and well-being of employees in these diverse work environments.

Key OSHA standards for general industry include:

• Hazard Communication (29 CFR 1910.1200)
• Machine Guarding (29 CFR 1910.212)

• Respiratory Protection (29 CFR 1910.134)
• Control of Hazardous Energy (Lockout/Tagout) (29 CFR 1910.147)
•  Personal Protective Equipment (PPE) (29 CFR 1910.132)

While construction and general industry have their unique challenges, there are common threads that run through OSHA standards. These shared principles include the importance of proper training, hazard identification, and the use of  personal protective equipment.

OSHA Enforcement

Inspection Process

OSHA conducts inspections to ensure employers comply with safety regulations. These inspections can be planned, programmed, or in response to a complaint or accident. During inspections, OSHA inspectors examine the workplace, review records, and interview employees to identify potential hazards.

Penalties for Non-Compliance

Non-compliance with OSHA standards can lead to severe penalties for employers, including fines and potential legal action. The severity of penalties depends on the gravity of violations and the employer’s history of non-compliance.

OSHA Training Requirements

Importance of Training

Training is a cornerstone of OSHA’s approach to workplace safety. Properly trained employees are better equipped to identify hazards, use  safety equipment, and respond to emergencies effectively.

Training Guidelines

OSHA sets specific training requirements for various industries. Employers must provide training to employees on topics relevant to their job responsibilities, ensuring that workers have the knowledge and skills needed to work safely.

Employees have the right to a safe workplace, free from recognized hazards. They can request an OSHA inspection if they believe their workplace is unsafe and can participate in safety and health committees.

Employees also play a vital role in workplace safety. They must comply with all safety regulations, report hazards, and use provided safety equipment correctly.

Employers bear the responsibility of creating and maintaining a safe working environment. This includes providing training, implementing safety programs, and ensuring that employees have access to necessary safety equipment.

In the world of industry and construction, safety is non-negotiable. OSHA’s unwavering commitment to establishing and enforcing safety standards has made a profound impact on workplace safety.

By understanding OSHA standards and fostering a culture of safety, employers and employees alike can contribute to a safer and more secure work environment. Source

What Causes Structures to Collapse due to Earthquake

The effects of earthquakes on structures can be devastating and sometimes catastrophic. Structures need to be built to withstand seismic activity to mitigate the impacts of such events. The underlying cause of structures collapsing due to earthquakes often has to do with design, construction, and maintenance. In this article, we discuss the main causes of structural collapse during an earthquake and provide insights for civil engineers on how to design and construct structures that are resilient to seismic activity.

One of the main causes of structural collapse during earthquakes is poor design. For instance, buildings that are not designed to withstand the lateral forces exerted by an earthquake can easily collapse. In addition, buildings that are not properly reinforced are also susceptible to collapse. In many cases, the use of sub-standard materials and construction methods can also contribute to the collapse of a structure during an earthquake.

Another cause of the collapse is poor construction. This can happen when buildings are not constructed according to their designed plans. For example, if the foundation of a building is not properly dug or if the building is not properly reinforced, it is more likely to collapse during an earthquake.

The third cause the  of structural collapse is poor maintenance. When buildings are not properly maintained, they become weaker and more susceptible to damage. This is especially true for buildings that are located in areas with high seismic activity. For instance, if the foundation building cracks, it can cause the building to collapse during an earthquake.

As civil engineers, it is important to design and construct buildings that are resilient to earthquakes. In addition, it is important to properly maintain buildings to ensure their strength and stability.

Foundation Failure Due to Soil Liquefaction

Soil liquefaction occurs when loose and water-saturated soil temporarily loses its strength and stiffness. This phenomenon is also known as earthquake ground failure, because it occurs most frequently in areas with high seismic activity that have loose, saturated soils.

Falling buildings due to soil liquefaction can occur even when the earthquake magnitude is low, particularly if the soil is sandy or unconsolidated. Soil liquefaction may cause significant damage to property and loss of life. Anyone who has built on a landfill site should be aware of the risk of liquefaction during a major earthquake. When the internal soil layers are liquefied as indicated in the above figure, there will be additional bending moment and shear forces developed in the pile that would cause the failure of the pile foundation if the section reinforcements are not adequate to bear the additional stress.

Short column Effect

Short column causes structural failures of the buildings. A short column is a kind of column that is have the height considerably less than the other columns. Though the frame structure itself the has same column height, construction partition walls could reduce the effective height of the columns.

Excessive Settlement

Soil liquefaction, having compressive soil that are not properly treated before the construction of the structure could undergoes excessive deformation due the seismic event.

Liquefaction of internal soil layer could cause settlement of the topsoil layers together with the building foundation.

If the unbalance soil capacities are induced with ground shaking, building could overturned.

Overturning of Buildings

Overturning of the building could be due two main reasons.

Soil bearing failures

• P – delta effect
• Soil Bearing Failure

Due to the shaking of the building in the vertical and horizontal direction soil under the foundation subjected to the excessive stress. As a result of that, there are possibilities of foundation failure.

In a shallow foundation, failure of soil one part of the foundation could lead to overturn the building.

P-Delta Effect

Excessive deflection of the building causes the load eccentricity of the building. In addition, permanent deformation causes due to the action of an earthquake shift the load center of the structure.

Soft Stores

In the technical point of view, having low stiffens in the lateral direction when compared to the other floors can be considered as the soft story effect.

When the lateral loads from the earthquakes are applied, floors with high lateral safeness will be able the bear the forces and control the lateral deflections. However, soft story will have excessive lateral deformation leading the failure of the floor. These kinds of failures result in collapse of the structures.

Torsional behavior of structure in a earthquake would cause severe damage to the structure if it is not considered during the structural design. The most common practices is to modify the stiffness of the structure to avoid the torsional modes becomes dominant.

Insufficient Ductility

Ductility of the structure is very important factor considered in the design of structures against seismic loading. Right structure absorbs more energy and could cause failure. However, when the structure is ductile, it has more deformations.

The ductility of the structure is controlled by the reinforcement detailing. There are special requirement to be met when the detailing of the reinforced concrete element are made. Further, failure of the connection of the beam and columns, column and foundation could cause structural failure.

The hinge form close to the beam column connection. That area shall be detail in a way that it does not fail due to the cyclic loading applied seismic excitations, and to have adequate ductility.

Inadequate Lateral Stiffness 

Lateral loads applied on the structure will be shared by the reinforced concrete frame structure and the shear walls. In some structures, there would be shear walls. In such situations, frame structure will be taking the loads.

When there are shear walls and frame structure, shear wall and frame interaction can be considered for the design as it enhances the lateral load resisting capacity.

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