Calculate Wall Bracing - Part 4 - Design Bracing Systems - Nominal Bracing - Wind Direction 1

Summary

In this fourth installment of the 'Buildsum' series, the focus shifts to designing bracing systems for walls. The video explains the concept of 'nominal bracing,' which relies on internal lining materials like Gyprock. It outlines rules for using nominal bracing, such as its capacity to resist only 50% of the total racking force and exclusion of panels smaller than 450mm. Using the example of a house, the video demonstrates how to calculate the resistance provided by nominal bracing for both single and double-sided walls, ultimately determining the total resistance needed in Wind Direction 1. The video promises to address Wind Direction 2 in the next episode.

Takeaways

• 🏗️ The video discusses the design of bracing systems for walls, focusing on 'nominal bracing' as the initial topic.
• 📝 Nominal bracing is made up of internal lining materials such as Gyprock or villaboard, which play a crucial role in wall stability.
• ⚠️ There are limitations to using nominal bracing; it can only resist up to 50% of the total racking force in any direction.
• 📏 A panel size less than 450mm cannot be considered for nominal bracing calculations, emphasizing the importance of panel dimensions.
• 📚 The Timber Framing Code provides specific capacities for nominal wall bracing: 0.45 kN/m for single-sided walls and 0.75 kN/m for double-sided walls.
• 📐 The process involves calculating the total length of walls that contribute to bracing and multiplying by the bracing capacity to determine resistance.
• 🏡 In the example house, the total bracing capacity for single-sided walls is calculated by adding the lengths of the walls and multiplying by 0.45 kN/m.
• 🔢 For double-sided walls, the calculation is similar but uses the 0.75 kN/m capacity, resulting in a combined resistance from nominal bracing for Wind Direction 1.
• 📉 After calculating the resistance provided by nominal bracing, the video concludes that additional resistance is required beyond what nominal bracing can provide.
• 🌪 The video script also mentions that the next part of the series will address Wind Direction 2, indicating a continuation of the topic.
• 📺 The presenter encourages viewers to subscribe or follow on social media for more informative videos on similar topics.

Q & A

What is the main topic of this video?

The main topic of this video is the design and calculation of wall bracing systems, specifically focusing on nominal bracing.

What is the purpose of calculating the racking force on a wall?

The purpose of calculating the racking force on a wall is to determine the force that will act on the wall due to wind pressure, which is essential for designing the bracing to resist that force.

What is the wind direction that resulted in the highest racking force in the example provided?

Wind Direction 1 resulted in the highest racking force of 47.908 kN in the example provided.

What is the maximum percentage of the total racking force that nominal bracing can resist?

Nominal bracing can resist up to 50 percent of the total racking force in any direction.

Why can't a panel size less than 450mm be considered in the nominal bracing calculations?

A panel size less than 450mm cannot be considered in the nominal bracing calculations because it is too small to contribute effectively to the overall bracing capacity.

What are the bracing capacities per meter for single-sided and double-sided walls according to the Timber Framing Code?

According to the Timber Framing Code, the bracing capacity for single-sided walls is 0.45 kN per meter, and for double-sided walls, it is 0.75 kN per meter.

How is the total bracing capacity of nominal bracing calculated for single-sided walls in the example house?

The total bracing capacity for single-sided walls is calculated by adding the lengths of the walls (16.2m) and multiplying by the bracing capacity per meter (0.45 kN/m), resulting in 7.424 kN.

What is the total resistance from nominal bracing in Wind Direction 1 for the example house?

The total resistance from nominal bracing in Wind Direction 1 for the example house is 21.150 kN.

What is the remaining racking force that needs to be resisted after accounting for the nominal bracing in Wind Direction 1?

After accounting for the nominal bracing, the remaining racking force that needs to be resisted in Wind Direction 1 is 26.758 kN.

What is the next step after calculating the nominal bracing for Wind Direction 1?

The next step, as mentioned in the video, is to calculate the bracing for Wind Direction 2.

Outlines

00:00

🏗️ Designing Wall Bracing Systems

This paragraph introduces the process of designing wall bracing systems, focusing on 'Nominal bracing.' The speaker explains that the internal lining of a wall, such as Gyprock or Villaboard, constitutes the nominal bracing. It is highlighted that nominal bracing can only resist up to 50% of the total racking force in any direction, and panels smaller than 450mm are not considered in calculations. The capacity of nominal wall bracing is given as 0.45 kN per meter for single-sided walls and 0.75 kN per meter for double-sided walls. The example of a house is used to calculate the resistance provided by the nominal bracing in Wind Direction 1, with the total length of walls and their respective capacities being factored into the calculation.

05:00

🔢 Calculating Required Bracing Force

In this paragraph, the speaker continues the discussion on wall bracing by calculating the remaining force that needs to be resisted after accounting for the nominal bracing's contribution. The calculation shows that after subtracting the resistance provided by the nominal bracing (21.150 kN) from the total racking force in Wind Direction 1 (47.908 kN), there is still a requirement for an additional 26.758 kN of resistance. The speaker reassures that the 50% rule does not apply in this case since the required force is less than half of the total racking force. The paragraph concludes with a teaser for the next video, which will address Wind Direction 2, and an invitation for viewers to subscribe or follow for more content.

Keywords

💡Wall Bracing

Wall bracing refers to the structural support systems used to strengthen walls against lateral forces such as wind, earthquakes, or other loads. In the video, wall bracing is the central theme, focusing on calculating and designing these systems to ensure the stability and safety of a building. The script discusses calculating the racking force due to wind and how to design bracing systems to resist that force.

💡Racking Force

Racking force is the lateral force that acts on a structure, typically due to wind or seismic activity. It causes the structure to rack or deform. In the script, the racking force is calculated for two wind directions, with values of 47.908 kN for Wind Direction 1 and 20.254 kN for Wind Direction 2, which are critical in determining the necessary bracing strength.

💡Nominal Bracing

Nominal bracing is a term used to describe the inherent structural strength provided by the internal lining of a wall, such as Gyprock or villaboard. It is a key concept in the script, where the presenter explains that nominal bracing can only be used to resist up to 50% of the total racking force in any direction, and certain panel sizes are excluded from calculations.

💡Gyprock

Gyprock is a type of plasterboard used as an internal lining in walls. It is mentioned in the script as a component of nominal bracing, contributing to the wall's resistance against racking forces. The script discusses how Gyprock and similar materials are factored into the calculations for wall bracing capacity.

💡Villaboard

Villaboard is another type of lining board used in wall construction, similar to Gyprock. It is mentioned alongside Gyprock as part of the nominal bracing in the script. Villaboard contributes to the wall's overall strength against lateral forces, and its inclusion in the bracing calculations is based on certain rules and limitations.

💡Timber Framing Code

The Timber Framing Code is a set of guidelines or standards that dictate the construction and design of timber-framed structures. The script references the code to explain the bracing capacities for single-sided and double-sided walls, which are crucial in calculating the nominal bracing's ability to resist racking forces.

💡Bracing Capacity

Bracing capacity refers to the amount of force a bracing system can withstand. In the script, the bracing capacity is calculated based on the length of the walls and the type of bracing (single-sided or double-sided). The Timber Framing Code provides the values of 0.45 kN per meter for single-sided walls and 0.75 kN per meter for double-sided walls.

💡Wind Direction

Wind direction is a critical factor in determining the racking force on a structure. The script discusses two wind directions, each with different racking forces. The design of the bracing system must consider these directions to ensure adequate resistance against the wind's impact.

💡Internal Lining

Internal lining is the material used to finish the interior surfaces of walls, such as Gyprock or villaboard. In the context of the script, the internal lining contributes to the nominal bracing, providing structural support against lateral forces. The script emphasizes that the internal lining is a crucial component in calculating the wall's resistance.

💡50% Rule

The 50% rule mentioned in the script is a guideline stating that nominal bracing can only be used to resist up to 50% of the total racking force in any direction. This rule is important in the design process to ensure that the bracing system is adequate and does not rely solely on the nominal bracing for its full resistance.

Highlights

Introduction to designing bracing systems for walls in part 4 of the series on calculating wall bracing.

Explanation of 'Nominal bracing' and its significance in wall design.

Recalling the calculated pressure applied to the wall from previous discussions.

Detailing the racking force calculations for Wind Direction 1 and Wind Direction 2.

Limitation that nominal bracing can only resist 50% of the total racking force in any direction.

Rule about not considering panels less than 450mm for nominal bracing calculations.

Distribution of nominal bracing should be even throughout the building.

Capacity of nominal wall bracing for single-sided and double-sided walls as per the Timber Framing Code.

Method to calculate the length of walls for bracing capacity assessment.

Example calculation for single-sided walls using the bracing capacity per meter.

Calculation of total bracing capacity for double-sided walls and the process involved.

Summation of resistance from nominal bracing for Wind Direction 1.

Analysis of the remaining resistance required after accounting for nominal bracing.

Confirmation that the calculated nominal bracing does not exceed the 50% rule.

Upcoming discussion on Wind Direction 2 in the next video.

Invitation to subscribe to the YouTube channel and follow on Facebook for more content.

Transcripts

Gday and welcome back to Buildsum and this is part 4 in the series on

calculating wall bracing and now we're going to start looking at designing the

bracing systems and the first thing we can look at as far as that's concerned

is what we call Nominal bracing okay so just to recap so previously we worked

out the, the pressure that it's going to be applied to our wall and we know that

Wind Direction 1 had an area elevation of 43.553

square metres which gave us a total racking force of 47.908 kN

okay that's the force that is going to act on that wall and for wind

direction too we had 20.254 kN acting in Wind

Direction 2 so now we're going to look at actually designing the bracing to

resist that force and the first thing we have to consider is what we called

nominal bracing okay so nominal bracing is basically made up of what our

internal lining is so for using Gyprock, villaboard

or any type of lining boards our internal lining makes up our nominal

bracing so a couple of rules around that we can only use nominal bracing to

resist 50 percent of the total racking force in any direction and if

there's a panel size that's less than 450mm we can't consider it okay so if

you go to a section of wall let's left and less than 450mm long you can't

include that in your calculations okay and it should be evenly distributed

throughout the building okay other well that should be pretty normal

okay so the tables in the Timber Framing Code say that the capacity of nominal

wall bracing for single sided walls is 0.45 kN per meter and for

walls sheeted on both sides its 0.75 kN per meter so basically what

we have to do is work out the length of those walls in the building

then times it by the bracing capacity that will give us how much resistance

the nominal bracing is going to give us let's do that with our example house so

Wind Direction 1 is down the bottom here the wind's blowing against

the long side the house so that all the walls at 90 degrees to the Wind

Direction alright will be resisting that so yeah 90 degrees or the same

direction as the actual wind direction, I guess, now there the walls that are

actually resist it, Because the wall the wind will blow against this wall and

these walls will help resist the load if you know what I mean so the first time

we can look at is walls with one side sheeted only so they are your external

walls because in this case there's a cavity and then the brickwork okay so

I've got the two external walls and then I've got these two ones here near the

near the door so we just work out the length of those walls so Wall 1 which

is starting on the left-hand side the long wall, 7m long, Wall 2, which

is next to the door it's 1.1m long

Wall 3, 1.1m long and the Wall 4, 7m long so we just add them up

there's me a total length of 16.2m and we times that by

our bracing capacity per metre which was 0.45 for single-sided walls so that

gives us a total bracing capacity of 7.424 kN for

the single sided walls so then we have to do the double sided walls so here

we've got a double sided walls highlighted so all these walls on this

side of the building pretty much the same length so I'm just going to work

them out all together okay so 4 walls, 2.5mlong there then we've got

this wall here so one wall at 3.5m long there and then these two, so two

walls at 2.4m long gives us 4.8 so again times, 4 x 2.5 gives you 10

1 x 3.5 gives you 3.5, 2 x 2.4 gives you 4.8, a total length of 18.3m

18.3 times our bracing capacity for

double-sided walls for two sides 0.75 gives us 13.725kN so we add those two amounts together we

get a total resistance from our nominal bracing in wind direction one of

21.150kN so we can go back over. so we've worked at a

nominal bracing of 21.150 so we required

47.908 minus the

21.150 it's less than a half so we do not have to worry about the 50%

rule so we still require 26.758kN of

resistance in when Wind Direction 1 all right so that's Wind Direction 1

done in the next video I'll have a look at Wind Direction 2

G'day I'm back just let you know that if you like this video you can subscribe

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