Workshop Combined 5-9 - Lecture notes 10 PDF

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CVEN2101 Engineering Construction

Workshop 5 Solution Building Structures

1. A client is planning to construct a storage room with the dimensions of 4m by 6m and the height of 2.8m in the backyard of his house with the plan below. This storage has a door with the dimensions of 0.90m (W) by 1.8m (H), and two windows with the size of 1.8m (W) by 1.2m (H). The floor will be a 150mm concrete slab with two layers of steel mesh SL82. The roof will also be concrete slab with the thickness of 200mm with N16 steel bars at the bottom @100mm both directions and one layer of SL81 on the top.

A) Calculate how much steel and concrete is required for on-gorund slab. Considering the price of concrete and steel $600/m3 and $3,800/ton, and the fixed price of steel fixing, formworking, and concreting of $1,000, how much will be the cost of on-ground slab construction? Allow 5% extra concrete and 20% extra steel for waste and overlapping.

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Solution: Required concrete for on-ground slab = 4m * 6m * 0.15m *1.05 = 3.78m 3 Size of a SL82 mesh is 6m * 2.4m and weight of a SL82 mesh is 52kg. Total mesh weight =

floor area mesh area

=

∗ no. of layers ∗ (1 + waste%) * weight of a mesh

24 14.4

∗ 2 ∗ 1.2 ∗ 52 = 208 kg = 0.208 ton

On-ground slab cost = 3.78 * 600 + 0.208 * 3,800 +1000 = $4,058.4

B) Client is considering the following three options for construction of the walls. i)

Double-wythes brick wall with cavity

Considering the brick size of 100mm (W) * 60mm(H) * 200mm(L), mortar joints of 10mm, and cavity width of 50mm, calculate the number of required brick and the volume of required mortar allowing 5% extra brick and 25% extra mortar as waste. Assuming $1.10 per each face brick including delivery, $1.25 for construction of each brick, and $300 for each cubic meter of mortar, what will be the bricklaying cost of this storage? Solution: Area of openings = 2 * 1.2 * 1.8 + 1.8 * 0.9 = 5.94m2 2

Width of the wall = 100mm + 50mm + 100mm = 250mm = 0.25m Length of the wall = (6m + (4m – 0.25 – 0.25)) * 2 = 19m Net area of the walls = (length of the wall * height of the storage) – openings area = (19*2.8) – 5.94 = 47.26m2 Surface area of one brick including mortar = (0.06+ 0.01) *(0.2+0.01) = 0.0147m2 Number of required bricks including waste = waste percentage) =

47.26 0.0147

area of wall area of one brick

* number of wythe * (1+

* 2 * 1.05 = 6752

Required mortar for each brick: Vb = 0.1 * 0.01 * (0.2 + 0.06 + 0.01) = 0.00027m3 Total volume of mortar: Vt = Vb * N * (1+ Pw) = 0.00027 * 6752 * 1.25 = 2.279m3 Cost of wall if brick is used = 6752 * (1.1+1.25) + 2.279 * 300 = $16,550.9

ii)

Using concrete blocks and filling with fresh concrete

If the size of blocks is 400mm * 200mm * 200mm and the mortar joint is 10mm, calculate the number of required blocks allowing 10% extra for waste, and the amount of fresh concrete required for filling the block holes. The holes of a concrete block includes around 70% of its whole volume. Assuming $6 per each concrete block including delivery, $5.50 for construction of each block, $600 for each cubic meter of concrete, and $300 for each cubic meter of mortar (1.5m3 of mortar is required), what will be the block lying cost of this storage? Allow 5% extra concrete for waste.

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Solution: New area of the walls is 47.82m2 (200mm width instead of 250mm) Surface area of one block including mortar = (0.4+ 0.01) *(0.2+0.01) = 0.0861m 2 Number of required bricks including waste = waste percentage) =

47.82 0.0861

area of wall area of one brick

* number of wythe * (1+

* 1 * 1.1 = 611

Whole volume of wall = area * thickness of wall = 47.82 * 0.2 = 9.564m3 Required volume of fresh concrete to fill the block holes = 0.7 * 9.564 * 1.05 = 7.030m3 Cost of wall if block is used = 611 * (6+5.5) + 1.5 * 300 + 7.030 * 600 = $11,694.5

iii)

Using 200mm dincel wall and fill with fresh concrete.

How many square meter of dincel panel and how many linear meter of guide track are required to complete this job? Assuming $95 per square meter of dincel panel and $25 per linear meter of guide track including delivery, $600 for each cubic meter of concrete, and $35 per square meter for labour cost to install, what will be the wall construction cost of this storage? Allow 5% extra concrete for waste. 4

Solution: Area of wall = 47.82m2 Length of wall = 19.2m Whole volume of wall = 9.564m3 Required volume of concrete = 9.564 * 1.05 = 10.042m3 Cost of wall if dincel wall is used = 47.82 * 95 + 19.2 * 25 +47.82 * 35 +10.042 * 600 = $12,721.8

C) Considering $100 labour cost per square meter for formworking, steel fixing, and concreting of the roof, and price of concrete and steel $600/m3 and $3,800/ton, what is the construction cost of the roof? Allow 5% extra concrete and 20 % extra steel for waste and overlapping.

Solution: Through the width of the roof, we need 40 steel bars with the length of 6m. Through the width of the roof, we need 60 steel bars with the length of 4m. In total, 480m of steel bar N16 is required for the bottom reinforcement layer of roof. The weight of steel bar N16 per meter is 1.618kg. Total weight of steel bar= 480 * 1.618 * 1.2 = 931.97kg

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Total mesh weight =

roof area mesh area

=

∗ no. of layers ∗ (1 + waste%) * weight of a mesh

24 ∗ 1 ∗ 1.2 ∗ 104.66 = 209.32 kg 14.4

Volume of concrete = 4 * 6 * 0.2 * 1.05 = 5.04m3 The cost of roof construction = (931.97+209.32) * 3.8 + 24 * 100 + 5.04 * 600 = $9,760.9

D) Calculate the total cost of constructing this building structure. Solution: Total cost = cost of on-ground slab + cost of wall + cost of roof Total cost (if brick is used) = $4,058.4 + $16,550.9 + $9,760.9 = $30,370.2 Total cost (if block is used) = $4,058.4 + $11,694.5 + $9,760.9 = $25,513.8 Total cost (if dincel wall is used) = $4,058.4 + $12,721.8 + $9,760.9 = $26,541.1

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2. What is cavity wall? Explain its purpose, its structure, and its advantages. Solution: Cavity wall is constructed with two separate walls for single wall purpose with some space or cavity between them. These two separate walls are called as leaves of the cavity wall. The inner wall is called as internal leaf and outer wall is called as external leaf.

For non-load bearing cavity wall, two leaves are of equal thickness or sometimes internal leaf with more thickness is provided. The cavity size should be in between 4 to 10cm. The internal and external leaves should have at least 10 cm thickness. The two leaves are interconnected by metal ties or links as shown in above figure. Weep holes are provided for outer leaf at bottom with an interval of 1 m. Weep holes and flashings provide a mechanism for drainage of the moisture or rainwater if they can penetrate through the outer layer of wall . Normal bricks are used for inner leaf and facing bricks are used for outer leaf. Different masonry is also used for cavity wall leaves. The leaves are connected by metal ties or wall ties, which are generally made of steel and are rust proof. The maximum horizontal spacing of wall ties is 900mm and maximum vertical spacing is 450mm. The wall ties are provided in such a way that they do not carry any moisture from outer leaf to inner leaf. Different shapes of wall ties are shown in below figure.

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Advantages 



Cavity walls give better thermal insulation than solid walls. It is because of the space provided between two leaves of cavity walls is full of air and reduces heat transmission into the building from outside. Economically they are cheaper than solid walls.



Moisture content in outer atmosphere is does not allowed to enter because of hollow space between leaves. So, they also prevent dampness.



They also act as good sound insulators.

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CVEN2101 Engineering Construction Workshop 6 T3, 2021 Solution In answering the following questions, they are programmed as discussion questions, and that requires you to attend your scheduled Workshop. Your Demonstrator will lead the Workshop discussion. You are expected to contribute to the discussion. 1. Explain what is meant by the term, Environmental Sustainability and how does it differ from Construction Sustainability? Environmental Sustainability is about the use of processes that enables material usage to be used, reclaimed and reused in a responsible way. Construction Sustainability requires the use of materials in a responsible way but also requires that an organisation to consider maximising profitability by reducingwaste, rework of construction processes and producing work outputs that meets the required specification requirements. In doing work in this way it also requires that the tasks are completed safely. An organisation able to achieve this will be at near industry best practice and will continue to thrive in that market Note that Environmental Sustainability can be achieved in the actions taken for Construction Sustainability. 2. List the hierarchy of the environmental sustainability principles? • Replace (by substitution of another product) • Reduce (by minimising waste or substituting an alternative product) • Reuse (by recycling) • Re-engineer (to improve the configuration) • Reclaim (by a further processing) • Re-educate (by training) 3. In Question 2, which is the easiest of the environmental sustainability hierarchical principles to achieve? This is to be a student-led discussion point. First 5 points in descending order require more and more energy being spent in the environmentally sustainable process. The last point, Re-educate, is about changing people’s thinking on what energy is associated within the hierarchy. Clearly, the biggest gains are achieved in Replace and Reduce, but it requires considered thinking in actioning these processes in real life! From a home perspective, most people recycle their waste using the colour-lidded recycle bins, thinking that their action/practice is a very sustainable action by sending the waste to reclamation. Better option is to think about their action and implement Replace and Reduce where-ever possible.

-24. What is different to how we as engineers view environmental sustainability by comparison to the how the ‘general public’ views environmentally sustainable matters? This is to be a student-led discussion point based on the discussion from Question 3. Consider: On a construction site, rainwater runoff has to be filtered to collect sediment, yet rainfall surface flows in our places of residence is allowed to flow straight the gutter. Is there a conflict environmentally between these two different practices here? 5. For the Sydney Light Rail Project or the Parramatta Light Rail Project discuss how the environmental sustainability principles have been employed in developing parts of that project. This is to be a student-led discussion point. 6. In the construction of the Sydney Light Rail Project or the Parramatta Light Rail Project are there any elements of the sustainability hierarchy that you detailed in Question 2 that a specialist sub-contractor could not influence in completing the task? (You might want to look at a particular construction task that the Head Contractor might let by Sub-contract and comment upon how the sustainability principles can be actioned by the sub-contractor. (E.g. Traffic control, specialist engineering design work [like drainage design], the installation of drainage pipelines, excavation tasks, etc.)

In answering this question subcontractors present a good exemplar. Sub-contractors are employed to perform specific tasks. It is usual that subcontractors have little ability to influence the planning process that allows Replace, Re-engineer and Reclaim actions for products and materials. Instead their Construction Sustainability is achieved by Reducing (waste and/or rework), Reuse (of materials) and by Re-education (through training to upskill a workforce to improve construction efficiencies. In ‘design and construction’ contracts the Head Contractor may be able to gain the efficiencies available through Replace, Re-engineer and Reclaim actions for products and materials because they have the time and ability to review alternate designs and consider construction alternative solutions. 7. If the project undertaking was now a fully designed structure (like a building; for instance, the replacement sports stadium to be built at Moore Park - adjacent to the Sydney Cricket Ground), how would the contractor selected to build it, maximise engineering sustainability for this work? (Again, use the hierarchy details in Question 2 to help you frame your answer.) For building construction jobs (as against civil infrastructure projects) the same principles, detailed in Question 4, still apply. In building construction work because the work is restricted to a small land area and the duplicated in the vertical plane (for multi-storey construction) there is the ability to tightly manage the construction processes, the work schedule and the construction program because of the repeatability of process. In a building construction job, the finesse and scrutiny of the work processes sees the Reduction of waste and the minimising of rework as the focus in maximising construction profitability and wherever possible, the Reuse of materials. In civil infrastructure projects, the sites are much larger and so there is likely to be geotechnical differences in the foundation material across the whole of the site. (Consider the length of the M7 motorway which was over 40 km in length.) These changes in foundation conditions, requires discrete engineering designs being made across the site. Clearly this draws on those with very special knowledge(s) and so in ‘design and construct’

-3contracts it allows for many alternative designs to be achieved before final selection of the most appropriate designs. 8. Why are sustainability matters best dealt with at the ‘planning stage’ of a project rather than just at the ‘construction stage’ of the work? This is to be a Student-led discussion point. 9. As you will be entering into the engineering workforce in a few short years from now, it will be imperative that you can adapt in your work practices to make yourself a ‘sustainable person’ in industry. Discuss some of the ways that you will maintain your relevance to the profession after you finish your engineering degree. Students need to think about where they will work within the Civil Engineering profession as they progress through 2nd, 3rd, and, 4th years to graduation! Design? (There are not many designers needed to design structures given proliferation of engineering analysis and design programs) • Construction? (Many more Civil Engineers are employed inn construction than in design. Ratio may be as high as 15 to 20: 1?) • Other? (Includes sales and marketing roles in material supplier organisations, education roles, engineering research roles, Project Management roles, further study at Master or PhD qualification levels, other tertiary training in another profession).

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Sustainability for you is about amassing new technical knowledges and skills and seeking out a mentor within industry to help you consolidate for your engineering understanding and having the communication skills to convey the information. There are other requirements that you need as well. The following elements are referred to as ‘soft skills’, on comparison to your ‘technical skills’ coming from you engineering training. So, how are your communication skills? Over time you will need to develop the skills (or be trained) to do the following: • Write an Engineering Report • Prepare and give a concise explanation about a topic • Research for information about a new topic or process • Prepare a Dot-point Brief • Prepare a speech for public address (say 10 minutes long) • Prepare a written critique • Work in a team environment with other professions • Be able to manage semi-skilled personnel or untrained personnel • Work safely • Manage the safety process so as others under your charge complete their work safely • Deal with owners, stakeholder groups, unions, and employees, • Mix socially with politicians and other dignitaries • Prepare quotations and Tender submissions (with others in a team) • Prepare a Specification • Prepare a construction program • Prepare a budget, manage a project and produce a profit • Manage project quality

CVEN2101 Engineering Construction Workshop 7 Solution Construction Equipment Introduction and Economics 1

1. What are the main applications of construction equipment? Name two equipment pieces for each application.

Solution: Equipment Applications: 1. Excavation and Loading (excavators and loaders) (CVEN2101) 2. Pushing and Hauling (dozers, trucks, and scrapers) (CVEN2101) 3. Finishing (rollers and motor graders) (CVEN2101) 4. Lifting (cranes and forklifts) (CVEN4102) 5. Tunneling (tunnel boring machines (TBM) and roadheaders) (CVEN4102)

2. A hydraulic excavator with the bucket capacity of 1.15 m3 is used for excavating the basement of a building. The material is common earth with the bucket fill factor of 0.90, and the job efficiency is estimated to be 50 minutes per hour. The machine’s maximum depth of cut is 7.3 m, and the average digging depth is 4 m. Estimate the hourly production rate of this excavator if the average swing angle is 90 degrees.

Solution: P = C*B*S*V*E C = cycles/h C value depends on two parameters of bucket size and the type of material.

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Table 1

Bucket size = 1.15 (medium excavator), type of material = common

earth (average)

C = 160 cycle/h

B = bucket fill factor B = 0.90

S= swing-depth factor S value depends on two parameters of depth of cut and angle of swing. Swing angle = 90 degrees depth of cut = 4m/7.3m = 0.55 = 55% S value for swing angle of 90 degree and cut depth of 50% is 1.10. (Table 3) S value for swing angle of 90 degree and cut depth of 70% is 1.00. (Table 3) Interpolation is needed. So, S value for swing angle of 90 degree and cut depth of 55% is 1.075. Assume 1.08. V= bucket volume = 1.15 m3 E= job efficiency = 50/60 = 0.83 P = C*B*S*V*E = 160 * 0.90 * 1.08 * 1.15 * 0.83 = 148.44 m3/h

3. A contractor has two excavators with the bucket sizes of 0.85 m 3 (small excavator) and 1.20 m3 (medium excavator) in the equipment fleet. This contractor has recently won a tender for a project to excavate 40,000 m 3. The average depth of excavation is 4 m with common earth, and the maximum digging depth of these two small and medium excavators are 4.45 m and 5.7 m respectively. These two excavators work 45 minutes per hour with the swing angle of 120 degrees and bucket fill factor of 0.90. Considering that the total cost per hour for using the medium excavator is 30% higher than the smallsized excavator, select the optimal excavator for this project, and how many 2

days are needed to complete this project. Excavators work 8 hours per day from 7 am to 3 pm.

Solution: As the first step, the production rate of these two excavators is estimated. The optimal excavator is then selected through comparing the production rate and cost. Production rate of small excavator: P = C*B*S*V*E C = 200 cycles/h (small excavator, average material, Table 1) B = 0.90 S = 0.85 (swing angle =120 degrees, depth of cut =

4 4.45

= 0.90 = 90%, Table

3) V = 0.85 E=

45 60

= 0.75

P = 200 * 0.9 * 0.85 * 0.85 * 0.75 = 97.54 m3/h Production rate of medium excavator: P = C*B*S*V*E C = 160 cycles/h (medium excavator, average material, Table 1) B = 0.90 S = 0.94 (swi...