As a student or professional engineer, you are always faced with the challenge of making structures that can hold a lot of weight.
The bearing plate is an important part of a building's structure that helps keep the building stable.
Even though they look small, bearing plates spread the weight of a wall-bearing beam over a larger area.
This keeps the beam from warping, cracking, or even breaking in a big way.
If the bearing plates aren't chosen and put in the right way, the structure's integrity could be broken, which would pose serious safety risks.
In this article, I'll talk about the basics of bearing plates, including their types, how to choose them, and how to put them in place.
You'll learn a lot about how bearing plates are used in building and how to make sure your designs meet the highest safety and stability standards.
So let's jump in and learn about bearing plates.
Bearing Plates in Construction
Formal definition:
A flat steel plate is used under the end of a wall-bearing beam to distribute the load over a broader area.
A bearing plate is a special kind of metal plate that is used to spread the force of a load-bearing wall or column over a larger area.
It's usually less than an inch thick, but it's wide and long, and its length and width depend on what it's meant to fit under.
A bearing plate's job is to redistribute weight and keep structures from settling or sagging so that they last longer.
Types of Bearing Plates
Different kinds of bearing plates are used in construction, such as sliding bearings, rocker and pin bearings, roller bearings, elastomeric bearings, curved bearings, pot bearings, and disk bearings.
Each type is good for a certain use and has its own pros and cons.
Sliding bearings are made up of two metal plates that move relative to each other.
This allows for translational movement, and lubricants are put between the plates to keep them moving smoothly.
Rocker and pin bearings have the same shape, but pin bearings have a flat bottom that is attached to a concrete pier.
Roller bearings can be used to build bridges made of both steel and reinforced concrete.
Rubber is used to make elastomeric bridge bearings, which don't have any moving parts because the rubber itself lets the bridge move.
They are cheap to make and don't need to be maintained like other types of bearings.
Disk bearings are made for structures that have a lot of weight on one side or need to be able to turn.
Curved bearings allow the bridge to rock as it opens up to allow horizontal movement.
Pot bearings are made up of a shallow cylinder filled with elastomer and attached to a steel piston inside the cylinder.
The piston is then put on a polished stainless steel surface that lets it turn freely.
There are two main types of bearings that are used to build bridges: expansion bearings and fixed bearings.
Expansion joints let the structure expand or contract due to temperature changes without hurting the structure next to it.
Fixed joints support vertical loads and let the structure move horizontally due to temperature changes.
Uses of Bearing Plates
In building, bearing plates are used to move concentrated compressive forces from one structural element to another.
They are often used to spread the force of a steel beam over a larger area made of a less strong material than steel, like concrete or masonry.
The action is like a footing that spreads a heavy load over soft ground.
When the pressure under a beam flange is higher than what is allowed, a bearing plate should be put under the flange to spread the load of the beam over the concrete or masonry.
The beam load can be assumed to be evenly spread across the bearing plate over an area of 2kN, where k is the distance from the bottom of the beam to the web toe of fillet and N is the length of the plate.
In truss systems, a truss bearing enhancer can be used when the forces going through the triangles that connect them are more than what the beam or top plate can handle.
These metal plates take the load from the truss and come from different suppliers in different sizes and shapes.
Bearing plates are also used to test the flow of water.
The axial pull-out load from the hydraulic cylinder is spread evenly over the whole surface of the test sample by the bearing plate.
Materials Used in Bearing Plates
Slide plates, which are another name for bearing plates, can be made from many different materials, such as graphite, PTFE, 25% glass filled, stainless steel, and bronzphite.
Carbon steel is often used to make different parts for bearings.
Engineering ceramics are also used to make cutting tools, valves, nozzles, materials that keep heat out, and parts of buildings.
Polymers are good for cages because they are easy to work with and don't rust.
They can be used on their own or with functional fillers to make a composite material whose properties can be changed.
Discover the Unsung Hero of Construction: The Bearing Plate
Still hard to understand? Let me change the point of view a bit:
Want to make your next engineering project more interesting? Don't worry about the steel beams and high-tech parts.
Instead, pay attention to the humble bearing plate, which is the unsung hero of construction.
Yes, we are talking about a flat steel plate that sits quietly under the end of a wall-bearing beam, distributing loads and preventing a catastrophic failure.
Forget about cool gadgets and the latest technology.
When it comes to building safety and stability, the bearing plate is the most important thing.
So, grab your flat steel plates, engineers, and let's get started!
Okay, that was just a joke made to look like a TV ad.
Now let's go back to the explanation.
Load Bearing Capacity of Steel Plate
To figure out how much weight a steel plate can hold, we need to know how thick the plate is and how strong the steel is.
Yield strength is the most stress a material can take before it changes permanently.
You can figure out how much weight the plate can hold by multiplying the thickness of the plate by the yield strength and then multiplying that number by a safety factor.
Performing a Plate Load Test
By causing the ground to settle with an increasing load on a circular steel plate, a plate load test can find out how strong the ground is and how much weight it can hold.
The size of the plate used in the test affects the bearing surface on the ground.
If a bigger plate is used, the bearing capacity value will be lower.
Interpreting Plate Load Test Results
To figure out what the results of a plate load test mean, we first have to figure out how much total load is needed to cause settlement.
Then, we can figure out the ground's ultimate bearing capacity (the most pressure that can be put on it vertically before it breaks) by dividing the total load by the area of the plate.
From here, we can figure out the safe bearing capacity of the ground by dividing the ultimate bearing capacity by a factor of safety (typically 3).
Calculating Load-Bearing Capacity for Beams
To figure out how much weight a beam can hold, we need to find its Ymax, which tells us how much it can bend in the middle.
Young's modulus, moment of inertia, length, and thickness are some of the variables in this equation.
Beam Bearing Plate Design
A bearing plate takes the force that a steel beam puts on it and spreads it over an area made of materials that aren't as strong as steel.
For designing beam bearing plates, we use SCM equations J8-1 and J8-2 to figure out Pp, which is the nominal concrete surface strength.
In short, you can find out how much weight a steel plate can hold by multiplying the thickness of the plate by the yield strength and then multiplying that number by a safety factor.
When you do a plate load test, you can find out how strong the ground is.
To understand the results, you have to figure out the total load value needed to cause settlement and the ground's safe and ultimate bearing capacity.
To figure out a beam's load-bearing capacity, you have to figure out Ymax.
To design a beam bearing plate, you have to figure out Pp, which is the nominal concrete surface strength.
Identifying Load-Bearing Walls
Load-bearing walls can be found by.
When planning a home improvement project, it's important to know which walls hold weight so you don't damage the building's structure.
Here are some ways to tell which walls carry weight:
Check from a basement or crawlspace for support structures under the first-floor wall.
It is probably a load-bearing wall if there is a beam, column, or another wall right below it or going in the same direction.
Load-bearing walls can also be outside walls that stand on the foundation sill.
Most walls that are more than 6 inches thick can hold weight.
- Talk to an expert in building, like an architect, carpenter, or structural engineer.
They can tell if the wall in question bears weight and needs a bearing plate.
- If the wall is perpendicular (at a 90-degree angle) to the joists above, it is likely to carry weight.
But it may not be load-bearing if it runs parallel to the floor joists above.
- Before removing any walls during home improvement projects, it's important to figure out which walls hold weight and which don't.
Identifying these types of walls should be done by structural engineers since it's not recommended for beginners.
Remodeling plans should pay extra attention to load-bearing walls when working on floors or roofs.
How to Replace a Rotten Bottom Plate on a Load-Bearing Wall:
When the bottom plate of a load-bearing wall has rotted, the wall must be propped up so that the roof and beams are supported.
Then, the studs and bottom plate must be taken out and replaced.
Here are the steps involved in replacing a rotted bottom plate:
Check with a structural engineer or building inspector to make sure that the load-bearing wall is properly supported during the repair process.
Also, safety measures, like wearing the right gear and using the right tools, should be thought about.
- Use temporary supports to hold up the load-bearing wall, such as a temporary wall under the ends of the garage ceiling joists that rests on the garage floor.
You can also build a temporary wall 12 to 24 inches inside the rotten one, from one end to the other, all the way up to the load-bearing truss bottoms or roof joists, and brace it on both sides to make a "X.
- Take anything heavy off the sill first.
Then, fix any damage and come up with a new sill and/or stud system that fits your needs and meets current building codes.
- Mark where the studs are on the old plate, and cut the nails between the plate and the studs with a reciprocating saw.
- Take off the old plate and studs and put in a new bottom plate that has been treated with pressure.
Anchor bolts should be used to connect the new plate to the foundation.
Framing nails or screws should be used to connect the studs to the new plate.
- Put a water-resistant barrier between the bottom plate and the foundation to stop water from causing rot in the future.
- When the repair is done, take down the temporary supports and make sure the wall is straight and level.
Before you start, you should talk to a professional if you aren't sure how to do the job or if the wall is load-bearing.
Clutch Throw-Out Bearings
A clutch throw-out bearing is a key part of the clutch system in a car.
During a gear change, it disconnects the engine from the transmission for a short time.
When you step on the clutch pedal, the throw-out bearing moves toward the flywheel.
This pushes the release fingers of the pressure plate in, which moves the pressure plate away from the clutch disc.
This moves the engine away from the transmission, making it easier to change gears.
Importance of the Throw-Out Bearing
The throw-out bearing is an important part of a car's clutch system and has a big effect on how the car drives and how it handles.
If the throw-out bearing starts to wear out, it can cause a number of problems, such as gear shifts that are stiff or slow, noise and vibration when the clutch pedal is pressed, and trouble changing gears.
Keeping your foot on the clutch pedal while driving can cause the throw-out bearing to wear out faster than it should because it is always engaged.
Symptoms of a Failing Throw-Out Bearing
If you notice any of the following, it could mean that the throw-out bearing is failing:
- Gear shifts that are stiff or slow.
- Noise and shaking when the clutch pedal is pressed.
- It's hard to change gears.
When you drive a car with a bad throw-out bearing, it can hurt other parts of the car, like the transmission.
With a bad throw-out bearing, it's not a good idea to keep driving, and a mechanic should check it as soon as possible.
Maintenance and Replacement
Most throw-out bearings last as long as the clutch does.
But if you see signs that something is wrong, you should have a mechanic check it out as soon as possible.
Regular maintenance of the clutch system, including checking the throw-out bearing, can prevent premature wear and tear and avoid costly repairs.
In case of a failing throw-out bearing, it is essential to have it replaced promptly by a professional mechanic.
To replace the transmission, the car has to be taken apart, which takes a lot of work.
So, it is very important to have it done by a skilled mechanic who can make sure the new bearing is put in correctly and works well.
Preventing Damage to the Throw-Out Bearing
Use the clutch pedal correctly to keep the throw-out bearing and other clutch parts from getting broken.
Don't rest your foot on the clutch pedal while driving.
This can cause the throw-out bearing to wear out faster than it needs to because it is always engaged.
Only use the clutch when you need to, and don't ride the clutch while you're driving.
Lubricants for Pilot Bearings and Flex Plates
Pilot bearings and flex plates in cars need to be oiled to keep them from wearing out too quickly.
Lithium-based grease for high temperatures is often suggested as a lubricant for these parts.
EP moly grease with an NLGI rating of 2 is also a good choice.
It is important to follow the manufacturer's instructions and use the right amount of lubricant to make sure it works right and avoid any problems.
Applying grease to a pilot bearing
When putting grease in a pilot bearing, you should put enough grease in but not so much that it runs down onto the clutch.
Some sources say to put grease in the hole of the bearing to make it easier to take the bearing out.
Applying oil to a sintered bronze bush
One source says that the best way to put oil in a bronze bush that has been smelted is to put it in oil in a vacuum.
But it's important to follow what the manufacturer says about how to grease this part.
Bearing plate
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Conclusion
As we finish talking about bearing plates, it's important to remember that these small but important parts have a big impact on the stability and safety of a building.
When chosen and put in the right way, they help spread loads and keep individual parts from being overloaded, which can cause a catastrophic failure.
As engineers, it's important to make sure that every part, no matter how small, gets the attention it deserves during the design process.
Bearing plates may not seem important, but they are very important to a building's structural integrity.
So, the next time you design a building, think about the bearing plates and how important they are to keeping the building safe and stable.
Remember that when it comes to engineering, every little thing matters, and it's often the small things that make the biggest difference.
Links and references
Steel Design Guide Series 1 - Column Base Plates
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