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A hub for civil engineering related designs, analysis, discussion, information, and knowledge.....

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Tuesday, December 18, 2018

Saturday, December 15, 2018

December 15, 2018

Plastic Analysis of Framed Structures


The fully plastic moment of a section (Mp) is the maximum moment of resistance of a fully yielded cross-section. The yielded zone due to bending where infinite rotation can take place at constant plastic moment (Mp) is called a plastic hinge. In order to find the fully plastic moment of yielded section, we normally employ the force equilibrium equation by saying that the total force in tension and compression at that section are equal.
December 15, 2018

How to Analyse Retaining Walls for Trapezoidal Load

In the analysis of retaining walls subjected to earth pressure, it is very common to observe trapezoidal load distribution on the walls. Normally, earth pressure on a retaining wall is assumed to adopt a triangular load distribution, but due to surcharge which is usually assumed to act on the ground surface, the top of the wall experiences some degree of lateral pressure.

Tuesday, November 27, 2018

November 27, 2018

Structural Design of Swimming Pools and Underground Water Tanks



I spent a large part of the last few months developing the contents of this booklet on 'Structural Design of Underground Water Tanks and Swimming Pools' (According to the Eurocodes). Water is necessary for survival of mankind, but in one way or another, water is relatively scarce. We all know that rain does not fall continuously, and for water to be available for usage in homes, it will have to be fetched/pumped from the stream, or harvested during rainfall, or dug up from the ground. As a result, survival instincts made man to create different means of storing water in order to face the periods of scarcity.

Friday, August 24, 2018

Tuesday, August 21, 2018

August 21, 2018

Is This Ultimate or Serviceability Limit State Failure?

Kindly look at the image carefully, and lend your professional opinion if the failure of the building will be categorized under ultimate or serviceability limit state. By posting and discussing your opinion on the comment section, I am very certain that knowledge and deeper understanding of this topic will be enhanced.

Saturday, August 18, 2018

August 18, 2018

Aspects of Modelling of Shear Walls

Shear walls are structural elements usually employed in tall buildings to assist in resisting lateral loads. Shear walls can be solid or pierced (coupled), depending on their location in the building. In the design of  tall buildings, structural engineers normally throw the entire lateral load (say wind action) to the shear walls, which means that the columns will not be relied on for lateral stability. In a more practical scenario however, the shear walls and columns interact in resisting lateral loads, which can be taken into account.

Thursday, August 16, 2018

August 16, 2018

A brief Presentation on Flexural Buckling of Columns

Introduction
When structural members are subjected to compressive forces, the members may fail before the compressive resistance (A.fy) is reached. This premature failure is usually caused by secondary bending effects such as imperfections, eccentricity of loading, asymmetry of the cross-section etc. In such cases, the failure mode is normally buckling, and this is unlike when the member is subjected to tensile forces, where the member will generally fail when the stress in the cross-section exceeds the ultimate strength of the material. Members subjected to tensile forces are inherently stable.

Tuesday, August 14, 2018

August 14, 2018

Structural Design of Cantilever Slabs - Solved Example



Cantilever slabs are common features in buildings due to the need to have bigger spaces at upper floors. To achieve this, architects normally extend the slab beyond the ground floor building line, thereby forming a cantilever. In this post, we are going to show how we can analyse and design cantilever slabs subjected to floor load and block work load.

Wednesday, August 8, 2018

August 08, 2018

How to Calculate the Quantity of Mortar for Laying Blocks


Engineers, site managers, and quantity surveyors are always faced with the challenge of specifying as accurately as possible, the quantity of materials needed to execute a specific item of work. In this post, we are going to explain how you can estimate the quantity of mortar (cement and sand) needed to lay blocks per square metre of wall.
August 08, 2018

Analysis and Design of Pedestrian Bridge Using Staad Pro


Pedestrian bridges (footbridges) are structures designed to enable human beings cross over obstacles such as busy highways, water bodies, gullies, etc. There are several variations of foot bridges based on structural configuration and materials. Modern footbridges are increasingly becoming elements of street beautification, with a view on sustainability and environmental friendliness. In this post, a simple pedestrian bridge has been modelled on Staad Pro software, and the result of internal stresses due to crowd load on the bridge presented.

Saturday, August 4, 2018

August 04, 2018

Bonding of Old and New Concrete


In construction, there always comes a time when there is need to bond old hardened concrete (substrate) with fresh concrete topping/overlay. This post aims to explain how to bond old and fresh concrete successfully, and also review the strength of  interfacial bond between old and new concrete based on already carried out experimental works.




Bonding is very important for adequate performance of finished concrete when fresh concrete topping is used to overlay an existing hardened concrete. This construction feature is usually found during bridge deck construction, concrete pavement, precast filigree slab, pile caps (in some cases) etc. The truth is that adequate bonding is not always guaranteed between the two layers, unless adequate precautions are taken.

For adequate bonding, it is very important to prepare the surface of the substrate adequately. The preparation of the surface usually involves roughening the surface, and removal of all dirt, oil, grease, loosened or unbonded portions of the existing concrete. By implication, the surface of the substrate should be hard, firm, clean, and free from loosened particles. This can be achieved by the use of chipping hammers, wire brushing the surface etc. After this is done, the exposed concrete surface can be cleaned by using pressurised clean water, air, etc. The man hours involved depends on the area of the surface, location, and the ease of cleaning (e.g reinforcement interference).

Precast Filigran Slab





After surface preparation, there is usually need to apply bonding agent on the surface of the existing concrete in order to facilitate the bonding. Epoxy based bonding agents are very popular for such operations. It is recommended that bonding agent is applied prior to casting the fresh concrete.  In essence, the procedure should be 'wet-to-wet' as the bonding agent should not be allowed to dry before the fresh concrete topping is placed.

Hardened Concrete With Bonding Agent Ready for Topping/Overlay
In a research carried out by Vandhiyan and Kathiravan (2017), the compressive strength of monolithic and bonded concrete was compared using 150mm x 150mm cube specimens at 28 days. With epoxy based bonding agent, the compressive strength of the bonded concrete was about 5% less than the monolithic strength, while without bonding agent, the compressive strength was about 28% less than the monolithic compressive strength.

Research has also shown that the moisture condition of the substrate affects the shear bond strength of bonded concrete. Shin and Wan (2010) investigated the interfacial bond strength of old and new concrete considering saturated surface dry (SSD) and air dry conditions. Saturated surface dry is  condition that can be described as the concrete containing moisture that is equal to its potential absorption, without the surface being wet or damp. At water/cement ratio of 0.45 (for the topping concrete), the shear bond strength at the interface was about 44% greater when the substrate was at SSD condition than when it was air dry. At water/cement ratio of 0.6 for the topping layer, an increase in shear bond strength was recorded, but there was a reduction in the compressive strength of the concrete.

So the recommendation in this article is that when casting a topping layer of fresh concrete on old concrete, adhere to the following guidelines;

(1) Prepare the surface properly
(2) Make sure that the substrate is at saturated surface dry condition
(3) Use a bonding agent and follow the manufacturer's technical recommendation properly.

Thank you for visiting Structville today, and God bless.

References
Vandhiyan R., Kathiravan M. (2017): Effect Of Bonding Chemical On Bond Strength Between Old And New Concrete. SSRG International Journal of Civil Engineering- (ICRTCETM-2017) - Special Issue – April 2017 ISSN : 2348 – 8352 pp 129-134

H-C. Shin,  Z. Wan (2010): Interfacial shear bond strength between old and new concrete. Fracture Mechanics of Concrete and Concrete Structures - Assessment, Durability, Monitoring and Retrofitting of Concrete Structures- B. H. Oh, et al. (eds) ⓒ 2010 Korea Concrete Institute, Seoul, ISBN 978-89-5708-181-5 pp 1195 - 1200



Thursday, August 2, 2018

August 02, 2018

Meet the Winners of Structville Design Competition

In the month of May, we announced the commencement of Structville Design Competition, where civil engineering students and serving NYSC members from various universities and polytechnics in Nigeria competed for small tokens in the design of reinforced concrete structures. The exercise was aimed at developing the interest of students in Structural Design, and preparing them for excellence in the field of structural engineering. You can view the details of the competition below;
August 02, 2018

A simpler Approach to the Design of Ground Beams Using Staad Pro


Ground beams are employed in reinforced concrete substructures for a lot of reasons. Ground beams can be differentiated from plinth beams due to a slight variation in the purpose of their construction. Plinth beams are used to connect (chain) separate pad bases together, and blockwork can be built off from the plinth beams. On the other hand, ground beams are designed mainly for the purpose of receiving load from ground floor slab or raft, alongside other functions as envisaged by the designer.

Monday, July 23, 2018

Friday, July 20, 2018

July 20, 2018

Comparative Design of Staircase Using StaadPro and Manual Calculations


Staircases provide simple solutions for vertical circulation in a building. In this post, we are going to model a simple  staircase using finite element plates, and compare the answer with manual calculations in which we assume the staircase to be a simply supported beam. The aim of this post is to verify the results obtained from the different procedures, and give reinforced concrete designers a little idea about the results to expect from their assumptions.

Tuesday, July 3, 2018

July 03, 2018

Structville Design Challenge Results (1st Edition)


On 14th of May, 2018, Structville Integrated Services announced the commencement of Structville Design Challenge for civil engineering students in Nigeria. (If you missed it, you can read post HERE). By the special grace of God, the competition has come and gone, and I wish to appreciate everyone who participated in the exercise.




The price money goes as follows;
1st position - NGN 10,000
2nd position - NGN 3,000
3rd position - NGN 2,000

Competition Details
Total number of successful applicants = 20
Total number of scripts submitted by dead line = 14
Total number of accepted scripts = 12
Total number of assessed scripts = 12

Rationale
Human capacity building in Nigeria has become a necessity, and we must all wake up to that fact. The motivation to start up something is one thing, but staying motivated to finish it up is another thing. The main aim of this competition was to steer the younger generation to a path of creativity, curiosity, technical capacity, problem solving, and tenacity. It was also designed to make them optimistic and look forward to a wonderful career in structural engineering.

While assessing the scripts, I made a lot of observations, and I will briefly summarise them using the points below;



(1) A lot of participants disregarded the first instruction of the exercise which was to pay attention to details. A lot of people lost marks by assuming weight of finishes, when the details of the finishes were clearly specified. Other people quoted values and formulars without properly referencing them. This affected a lot of people.

(2) In most cases, there was poor reading and interpretation of the architectural drawing. All those who modified the structure significantly lost a lot of marks.  However, I saw a lot of brilliance in some people with the way they managed the complexities of the architectural drawing, and produced a very good design. Some others came up with interesting GA's that are stable and buildable, but not very economical, so they lost marks in that aspect. For some others, they came up with GA's that are good, but did not reflect it properly in their analysis.

(3) No single person from South-East or South-South part of Nigeria participated in the exercise. I hope to see more of them next time.

(4) Finally, structural design is not about evaluating  M/fcubd2 and providing 2Y16, but it is more about the processes that led to the result, and the ability to execute the design economically, with adequate reliability.

So this is the result of the challenge;

I wish to say a very big congratulations to the winners;

1st Position - USMAN UMAR (Ahmadu Bello University, Zaria)
2nd Position - Ogungbire Adedolapo (Osun State University, Osogbo)
3rd Position - Olajide Bukoye (Federal Polytechnic Offa, Kwara State)

We will be celebrating them with their certificates and prize money in our next post. Structville will engage all the participants with corrections, recommendations, and discussion on all aspects of the design. Thank you, and God bless you.


Saturday, June 30, 2018

June 30, 2018

Design of Precast Seating Decks for Stadium


One of the most common construction concept of sports stadiums today normally involves having precast concrete terrace units (seating decks) span between inclined (raker) steel or reinforced concrete beams and rest on each other, thereby forming a grandstand. The raker beams are usually formed in-situ with the columns of the structure, and forms part of the structural frame of the grandstand. It is also feasible to construct precast raker beams as was done in the Corinthians Arena Sao Paolo, Brazil for the 2014 FIFA world cup.




Fig 2: Double L Precast Seating Deck


Fig 3: Structural Section of a grandstand

Precast seating decks are usually of L-shaped reinforced concrete units of length usually between 7-8 meters spanning between the raker beams. The seating decks also rest on each other. The role of the third (resting support) is to stop the units from undergoing excessive twisting, and in general, provide extra stability. Seating units are used to span between raker beams, and form the exposed surface which the seats are bolted onto. The seating units are fabricated in moulds depending on the length of the span, angle of inclination/curve, and support conditions.

Fig 4: Triple L Seating Deck being installed at Cape Town Stadium SA

Seating units can be easily installed on site, and when the joints between units have been sealed, form an effective barrier against external elements. Precast seating units can also be easily installed in steel structures.

Design Example
Let us design a 6m long precast seating deck for a stadium with a section shown below;


Fcu = 35 N/mm2; Fyv = 460 N/mm2; Fy = 460 N/mm2
Concrete cover = 30 mm
Unit weight of concrete = 24 kN/m3

Loading Analysis
Load type = uniformly distributed loading

Dead Load
Self weight of the unit = (24 × 0.15 × 0.25) + (24 × 0.15 × 0.95) = 4.32 kN/m
Make allowance for stair units and railings = 2 kN/m2

Live Load
For grandstands with fixed seating = 4 kN/m2
Making allowance for dynamic magnification = 5 kN/m2

At ultimate limit state;
n = 1.4gk + 1.6qk
n = 1.4(6.32) + 1.6(5) = 16.848 kN/m


Design Moment Mmax @ 3.0m = (ql2)/8 = (16.848 × 62)/8 = 75.816 KN.m
End shears = ql/2 = (16.848 × 6)/2= 50.544 KN

Design of the section to resist the applied moment
M = 78.816 KN.m
Effective depth d = h – Cc - ∅⁄2 - ∅links

Assuming Y16mm for main bars and Y8mm for links
d = 400 – 30 – 10 – 8 = 352 mm

b = bw = 150mm (since the flange is at the bottom)
k = M/Fcubd2 = (78.816 × 106)/(35 × 150 × 3522) = 0.121

la = 0.5 + √[0.25- 0.121/0.9] = 0.8399

ASreq = M/(0.95Fy.la.d) = (78.816 × 106)/(0.95 × 460 × 0.8399 × 352) = 610 mm2

In the web, provide 2Y16mm + 2Y12mm (ASprov = 628 mm2)
Provide 2Y12mm (Asprov = 226 mm2) in the compression zone.

Spread the As,req also along the width of the thread
Provide Y12 @ 175mm c/c Top and Bottom (Asprov = 646 mm2/m)

Distribution bars
Provide Y10 @ 200mm c/c as closed links




Check of Deflection
Basic span/effective depth ratio = 16 (for simply supported beams of b/ b < 0.3)

In this case bw/bf = (0.15)/(0.95) = 0.157

Modification factor for tension reinforcement
Service stress F.S = (2FyAsreq)/(3Asprov) = (2 × 460 × 610)/(3 × 628)
f.s = 297.9 N/mm2
m.f = 0.55 + (477 - Fs) / 120(0.9 + M/bd2)
m.f = 0.55 + (477 - 297.9) / 120(0.9 + 1.1445) = 1.28

Limiting span/effective depth = 1.28 × 16 = 20.48
Actual span/effective depth = 6000/352 = 17.045
Actual < Limiting, therefore deflection is satisfied


Design of the section to resist shear
Critical end shear = 50.544KN
Shear stress v = V/bd = (50.544 × 103) / (150 × 352) = 0.957 N/mm2

0.957 N/mm2 < 0.8 √35 < 5 N/mm2

Concrete resistance shear stress
vc = 0.632 × (100As/bd)1/3 × (400/d)1/4
vc =0.632 × [(100 × 628)/(150 × 352)]1/3 × (400/352)1/4
vc = 0.632 × 1.059 × 1.032 = 0.69 N/mm2

For concrete grades greater than 25 N/mm2
vc = vc(Fcu/25)1/3 = 0.69 × (35/25)1/3 = 0.772 N/mm2

0.772 N/mm2 < 0.957 N/mm2
0.5 vc < v < (vc + 0.4)

provide minimum links with spacing
sv = (0.95AsvFyv)/0.4bv
(Trying 2 legs of Y8mm bar)
sv = (0.9 5 × 107 × 460)/(0.4 × 150) = 735.62mm

Maximum spacing of links = 0.75d
0.75 × 352 = 264m
Provide Y8 @ 250mm c/c links

Detailing Sketches



Sunday, June 24, 2018

June 24, 2018

Concealing of PVC pipes in RC Columns


In modern building construction, PVC pipes (plumbing works) on the surface of buildings is not always very desirable. In a country like Nigeria, PVC surface pipes deteriorate quickly due to weather conditions thereby leading to increased maintenance costs. On the other hand, they are usually not aesthetically pleasing.

Fig 2: Surface piping in a building




To solve this problem, architects normally provide ducts for MEP services (which is the best practice) during the design of a building. Another option that is normally considered is to conceal the pipes in walls or structural members.

Two things are actually involved;

(1) If it is an intentional design, or
(2) if it is an afterthought.

When it is part of the design, the structural engineer takes into account the effect of the pipes before producing working drawings. But when it is an afterthought, there is need to carry out checks and evaluate the effect of the plumbing work on the structural element before signing off.

Fig 3: PVC pipe concealed in masonry wall
We have always seen situations in buildings where structural members are compromised in order to allow pipes and other services pass through. This should not be so because starting from the onset, we should realise that services are part of a building, and should be considered during the planning and design stage. The flow of services in a building should not be an afterthought.

Let us use this example below to highlight the effect of installing PVC pipes in reinforced concrete columns.

Example
What is the effect of passing a 75 mm diameter pipe longitudinally through an axially loaded short reinforced concrete column with the following data?

Size of column = 230 x 230 mm
Grade of concrete = 25 Mpa
Grade  of steel = 410 Mpa
Reinforcement provided = 4Y16
Design axial load on column = 593 kN




Solution
From equation (39) of BS 8110-1:1997;

N = 0.35fcuAc + 0.7fyAsc

From the data provided above;
Asc = 804 mm2 (4Y16)
A=  (230 x 230) - 804 = 52096 mm2
N = [(0.35 × 25 × 52096) + (0.7 × 410 × 804)] = 686588 N = 686.588 kN

686.588 kN > 593 kN (Therefore column is adequate without the pipe)

On introducing the 75mm PVC pipe;
Area of pipe = (π × d2)/4 = (π × 752)/4 = 4417.86 mm2

Hence;
A=  (230 × 230) - 804 - 4417.86 = 47678.14 mm2
N = [(0.35 × 25 × 47678.14) + (0.7 × 410 × 804)] = 647931.725 N = 647.931 kN
647.931 kN > 593 kN (Therefore column is still adequate with the 75 mm pipe passing through it)

However, we should anticipate more complex interaction and verifications when the loading of the column is complex. Apart from the reduction in load carrying capacity of columns, care should be taken to ensure that the concrete is well consolidated to avoid honeycombs especially around the pipes. Also adequate care should be taken to ensure that the pipes are not leaking (inclusive of the joints) by pressure testing before concreting is done. Leakage of pipes might compromise the reinforcements by corrosion.

Summarily, adequate design and planning for pipe network in a building is the best solution - all options available should be evaluated. As far as possible, it is best to let the structural members be.


June 24, 2018

Question of the Day (25/06/2018)





Structville daily questions
From now henceforth, Structville will be publishing daily questions on different aspects of civil engineering. You are expected to enter your response in the comment section. At the end of every week, exceptional participants will stand a chance to win some gifts. This exercise is open to participants all over the world.

Today's Question
What is the degree of static indeterminacy of the frame shown above?

Thank you for participating in exercise today, remember to enter your answer in the comment section. The main aim of this exercise to stimulate knowledge of structural analysis on the internet in a fun and exciting way. We are always happy to hear from you, so kindly let us know how you feel about Structville.

E-mail: info@structville.com
WhatsApp: +2347053638996

You can also visit Structville Research for downloads of civil engineering materials.

STRUCTVILLE REINFORCED CONCRETE DESIGN MANUAL
We have this very affordable design manual available...


Do you want to preview the book, click PREVIEW
To download full textbook, click HERE


Saturday, June 23, 2018

June 23, 2018

Basic Information on Fire Protection of Buildings


Fire outbreak is a problem in buildings since it causes loss of human lives, injuries, destruction of properties, and poses serious environmental challenges. Injury and loss of life are caused by heat, inhalation of toxic gases generated by combustion of furnishings/properties, falling debris, etc. Destruction of property and structural damage and failure are caused by heat and burning of combustible material.


Prevention and control of damage due to fire can be achieved through the following means;

(1) Early detection by smoke and heat detectors or manual sighting followed by extinction of the fire by automatic sprinklers, manual application of water, foams, fire extinguishers etc.

Fig 2: Fire Sprinkler System

(2) Containment of the fire by dividing the building into fireproof compartments to prevent fire spread and smoke travels, and provision of fireproof escape routes, fire rated doors and windows, fire rated finishes, etc.

Fig 3: Fire rated doors

(3) Fire protection of load bearing structural members to ensure collapse does not occur before people can escape or the fire be extinguished. This is usually achieved by giving the building a fire rating during the design process.

Fig 4: Beams and Columns Protected By Spraying 
The last two control methods form an essential part of the design considerations for steel structures (architectural and structural). All multi-storey commercial and residential buildings require fire protection of structural members, but single-storey and some other industrial buildings might not need protection.




Fire resistance requirements of buildings are usually based on the parameters influencing fire growth and development. These include:

  • Fire [probability of Fire occurrence, Fire spread, Fire duration, Fire load, Severity of fire…]
  • Ventilation conditions
  • Fire compartment (type, size, geometry)
  • Type of the structural element
  • Evacuation conditions
  • Safety of the rescue teams
  • Risk for the neighbouring buildings
  • Active fire fighting measures


Structural Considerations in Fire Design
Structural steelworks lose their strength on exposure to fire. Temperatures commonly reach 1200°C at the seat of the fire, while the critical temperature for steel is about 550°C. (see brief calculation below). At this temperature the yield stress of steel has fallen to about 0.7 of its value at ambient temperatures that is to the stress level in steel at working loads.


For instance in the calculation above, the critical temperature (failure temperature) is found to be 603°C (calculation according to EC3). The next step in the calculation is to determine the time at which the bare section reaches the critical temperature. This can offer the right information about the type of protection needed.

To request for a fully solved example of fire design (PDF) in a building, contact the author by clicking HERE.



Types of Fire Protection for Steel Structures
  • Solid protection for columns, where the concrete assists in carrying the load (this is not so much used in modern construction). Beams can also be cased in concrete. A concrete thickness of 50 mm will give about 2 hours protection.
  • Brick-clad steel-framed buildings, where brick provides the walling and fire protection, are a popular building system.
  • Hollow casing can be applied in the form of pre-fabricated casing units or vermiculite gypsum plaster placed on metal lathing.
  • Profile casing, where vermiculite cement is sprayed on to the surface of the steel member, is the best system to use for large plate and lattice girders and is the cheapest protection method. A thickness of 38 mm of cement lime plaster will give about 2 hours protection.
  • Intumescent coatings inflate into foam under the action of heat to form the protective layer.
  • Fire resistant ceilings are used to protect floor steel.
Thank you for visiting Structville today, and God bless you.



Monday, June 18, 2018

June 18, 2018

Design Example of Punching Shear in Slabs (Eurocode 2)





For the flat slab with the general arrangement as shown below, let us design the punching shear for column B1 given the following design information;

Ultimate axial force on column VEd = 400 kN
Thickness of slab = 250 mm
Dimension of column = 450 x 230 mm
Reinforcement of slab in the longer direction = H16@150mm (As,prov = 1340 mm2)
Reinforcement of slab in the shorter direction = H16@175mm (As,prov = 1149 mm2)
Grade of concrete = C30
Yield strength of reinforcement = 500 Mpa
Concrete cover to slab = 25mm


Solution
Effective depth of slab in y-direction dy = 250 - 25 - (16/2) = 217 mm
Effective depth of slab in x-direction dx = 250 - 25 - 16 = 209 mm

ρly = (1340) / (1000 × 217) = 0.00617 (reinforcement ratio)
ρlx = (1149) / (1000 × 209) = 0.00549 (reinforcement ratio)

(a) Check shear at the perimeter of the column

VEd = β VEd/(u0d) < VRd,max



From figure 6.21N of EN 1992-1-1;
β = 1.40
d = (217 + 209)/2 = 213 mm

u0 = c2 + 3d < c2 + 2c1 For edge columns (clause 6.4.5(3))


u0 = 230 + (3 × 213) <  (230 + 2 × 450)
u0 = 869 mm
VEd = 1.40 × 400 × 1000/(869 × 213) = 3.025 MPa
VRd,max = 0.5 ν fcd
= 0.5 × 0.6(1 - fck/250) × αcc fckm
= 0.5 × 0.6(1 - 30/250) × 1.0 × (30 /1.5) = 5.28 MPa
VEd < VRd,max ...OK




(b) Check shear at u1, the basic control perimeter
VEd = β VEd/(u1d) < VRd,c

β,VEd as before
u1 = c2 + 2c1 + π × 2d
u= 230 + (2 × 450) + (π × 2 × 213) = 2468 mm

VEd = 1.4 × 400 × 1000/(2468 × 213) = 1.065 MPa
VRd,c = 0.12 k(100 ρl fck)1/3

k = 1 + (200/d)1/2 = 1 + (200/213)1/2 = 1.969

ρl = (ρlyρlx)1/2 = (0.00617 × 0.00549)1/2 = 0.00582

VRd,c = 0.12 × 1.969(100 × 0.00582 × 30)1/3 = 0.613 MPa

VEd > VRd,c ?
1.065 MPa > 0.613 MPa ... Therefore punching shear reinforcement required

NA check:
VEd ≤ 2.0VRd,c at basic control perimeter
1.06 MPa ≤ 2 × 0.613 MPa = 1.226 MPa - OK

(c) Perimeter at which punching shear no longer required
uout = β VEd/(dVRd,c)
= 1.4 × 400 × 1000/(213 × 0.613) = 4289 mm

Rearrange: uout = c2 + 2c1 + π rout
rout = (uout – (c2 + 2c1))/π
rout = (4289 – 1130)/π = 1005 mm

Position of outer perimeter of reinforcement from column face:
r = 1005 – 1.5 × 213 = 686 mm

Maximum radial spacing of reinforcement:
sr,max = 0.75 × 213 = 159.75 mm, say 150 mm

(d) Area of reinforcement
Asw ≥ (VEd – 0.75VRd,c)sru1/(1.5fywd,ef)
fywd,ef = (250 + 0.25d) = 303 MPa

Asw ≥ (1.065  – 0.75 × 0.613) × 150 × 2468/(1.5 × 303)
≥ 492 mm2 per perimeter

Provide 7H10 (Asprov = 549 mm2 per perimeter)

Within the u1 perimeter the link spacing around a perimeter,
st ≤ 1.5d = 1.5 × 213 = 319.5 mm

Outside the u1 perimeter the link spacing around a perimeter,
st ≤ 2d = 426 mm
Use say st,max = 300 mm

Minimum area of a link leg:
Asw,min ≥ [0.053 sr st sqrt(fck)] /fyk = (0.053 ×  150 ×  300 ×  √30) / 500
≥ 26 mm2

Use H10s (78.5 mm2) and 7 per perimeter.
@ 300 mm tangential spacing and @150 mm radial spacing

Thank you for visiting Structville today and God bless you.


Sunday, June 10, 2018

June 10, 2018

Provision of Longitudinal Reinforcement in Piles: Solved Example


Precast piles are designed to withstand stresses caused during their installation, and the load from their service life. Bored piles on the other hand and usually designed to withstand the stresses they are subjected to while supporting the superstructure and other actions as may be anticipated. These could be earthquake forces, other lateral loads, or uplift forces. Furthermore, piles of all types may be subjected to bending stresses caused by eccentric loading, either as a designed loading condition or as a result of the pile heads deviating from their intended positions. This post is aimed at exploring the methods of providing longitudinal reinforcement for bored piles, and the minimum reinforcement acceptable.

Monday, June 4, 2018

June 04, 2018

Question of the Day (04/06/2018)


Structville daily questions
From now henceforth, Structville will be publishing daily questions on different aspects of civil engineering. You are expected to enter your response in the comment section. At the end of every week, exceptional participants will stand a chance to win some gifts. This exercise is open to participants all over the world. Happy new month to you all.




Today's Question
What is the vertical support reaction at point B of the frame?

Thank you for participating in exercise today, remember to enter your answer in the comment section. The main aim of this exercise to stimulate knowledge of structural analysis on the internet in a fun and exciting way. We are always happy to hear from you, so kindly let us know how you feel about Structville.

E-mail: info@structville.com
WhatsApp: +2347053638996

You can also visit Structville Research for downloads of civil engineering materials.

STRUCTVILLE REINFORCED CONCRETE DESIGN MANUAL
We have this very affordable design manual available...


Do you want to preview the book, click PREVIEW
To download full textbook, click HERE


June 04, 2018

Structville Online Professional Training and Webinars


Structville Integrated Services in our commitment to human capacity development, has decided to launch series of online lectures and webinars for civil engineering professionals and students. We wish to specify that this program is by choice, and there must be interest to participate before you can embark on this journey. We called it a journey because the whole program will be carried out online, and you should have enough data to download the videos, PowerPoint presentations, and papers that would circulated during the program. This is the only way you can maximize your benefits.

The program will last for 3 weeks (Friday 15/06/2018 to Friday 06/07/2018), and the arrangement is prepared in such a way that you will be able to download the resource materials and follow the discussions even if you are not online at a period that a particular session will be held. A time table would be published for the program, and it is advisable that you plan ahead and make yourself available so as to enable you ask questions. The promise is that all questions would be adequately attended to. We have mobilised distinguished resource persons from civil engineering profession all over the world to participate in the different sessions and give us the best ideas/interactions.

The online training has been divided into two categories;
- Category 1 -  ₦5,000
- Category 2 - ₦10,000

The topics to be treated are as follows;

Category 1 (₦5,000 / $15.00)
(1) Basis of Structural Design (PowerPoint Presentations, Papers, Case Studies, Discussions)

(2) Structural Analysis and Design of Office Complex Using Staad Pro Software (Video Tutorials, PowerPoint Presentations, Lecture notes)

(3) Structural Analysis and Design of Industrial Steel Structure Using Staad Pro Software (Video Tutorials, Powerpoint Presentations, Lecture Notes)

(4) Structural Analysis and Design of Beam and Raft Foundation Using Orion Software (Video Tutorials, Powerpoint Presentations, Lecture Notes)

(5) Matrix Methods of Structural Analysis - Force Method, Stiffness Method, and Finite Element Analysis (Lecture notes, Video Tutorials, Solved Examples)

(6) Life as a Civil Engineer and Challenges of the Industry (Power Point Presentations, Discussions, and Case Studies)

Category 2 (₦10,000 / $30.00)
(1) Leadership, Intelligence, Investment, and Capacity Building in Civil Engineering Profession (Papers, PowerPoint, Case Studies, Videos, Foreign Interactions)

(2) Basis of Structural Design (PowerPoint Presentations, Papers, Case Studies, Discussions)

(3) Limit State and Structural Reliability Theory (Papers, Lecture notes, and discussions)

(4) Structural Analysis and Design of Office Complex Using Staad Pro Software (Video Tutorials, PowerPoint Presentations, Lecture notes)

(5) Structural Analysis and Design of Industrial Steel Structure Using Staad Pro Software (Video Tutorials, Powerpoint Presentations, Lecture Notes)

(6) Structural Analysis and Design of Beam and Raft Foundation Using Orion Software (Video Tutorials, Powerpoint Presentations, Lecture Notes)

(7) Advanced Modelling and Analysis on Staad Pro - Bridges, Box Culverts, and Staircases (Video tutorials, PowerPoints,  and Lectures)

(8) Advances in Civil Engineering Materials (Videos, PowerPoint, Case studies, and Papers)

Followers of Structville blog can testify on our commitment to quality and excellence, and this webinar and online training will be another testimony. Just like I stated earlier, the idea is for you to have adequate data bundle beacause there will be excess downloads to make (especially for the videos). If you cannot afford it, do not bother yourself so much, but you would really miss. Structville's vision and mission is very accommodating.

REGISTRATION WOULD RUN FROM MONDAY 04/06/2018 TO THURSDAY 14/06/2018

To participate in this program, and for further inquiries, all you need is to send an e-mail and/or whatsapp message to;

E-mail: ubani@structville.com
WhatsApp: +2347053638996

To register expressly click HERE


Sunday, June 3, 2018

Thursday, May 31, 2018

May 31, 2018

Question of the Day (01/06/2018)


Structville daily questions
From now henceforth, Structville will be publishing daily questions on different aspects of civil engineering. You are expected to enter your response in the comment section. At the end of every week, exceptional participants will stand a chance to win some gifts. This exercise is open to participants all over the world. Happy new month to you all.




Today's Question
What is the deflection at point 2 of a structure if diagram (a) is the bending moment due to externally applied load, and (b) is the bending moment due to vertically applied virtual load at point 2? (The main bending moment diagram is obtained from equation of the form, wl2/2)

Thank you for participating in exercise today, remember to enter your answer in the comment section. The main aim of this exercise to stimulate knowledge of structural analysis on the internet in a fun and exciting way. We are always happy to hear from you, so kindly let us know how you feel about Structville.

E-mail: info@structville.com
WhatsApp: +2347053638996

You can also visit Structville Research for downloads of civil engineering materials.

STRUCTVILLE REINFORCED CONCRETE DESIGN MANUAL
We have this very affordable design manual available...


Do you want to preview the book, click PREVIEW
To download full textbook, click HERE