Pre-Engineered Frames

It is still very quiet in the construction sector. With the 15 cent decrease per liter in petrol price, I was hoping it will generate some activity. Unfortunately, I really cannot see any difference yet. Maybe its just too soon. Unfortunately, not everybody has the luxury of time, waiting for the economy to improve, as there are bills to be paid and mouths to feed. In the meantime, all we can do is wait, hope and pray…..(can also grumble and moan. Ha ha)

Heard people complaining that the prices of goods have not come down in tandem with the decrease in petrol prices. Hope the Government realize that its easy for prices to go up and so difficult to come down. In the future, I hope the next time we can elect leaders who well-versed in the workings of an economy. For example, I personally think, the former Prime Minister handled the economy very well.

My bank, just called to remind me of my monthly payment. My loan payment is due on the 15th every month, today is the 4th and they have already called me twice this month.! I sure wish they could be as efficient in their other activities. Like lending money to people who are in need instead of driving them to Ah Longs.

MY PRESENT JOBS

The only project I got lat week was an existing building, that the owners was thinking of adding another layer of roof on top of the existing layer. The reasons being, the present roof has rusted or something like that. The roof is supported by pre-engineered frames. Attached is a cross-section of the frame. Note: Pre-engineered frames are made up of tapered I-beams which supposedly tapers according to the magnitude of the Bending Moment at that particular section.

My task was to ascertain whether the present frames was strong enough to cater for the additional loads. As nobody has a copy of the old drawings and calculations, I had to re-analyzed the structure based on actual measurement of the existing steel frame etc.

I checked the frame at various locations (as the frame is tapered), had to work out the section properties at these locations. Then check biaxial bending at these points. To cut a long story short, the frame seems adequate.

Then I check the two interior columns (see above sketch) which were made up of UC254x254x 73kg/m. Note: the height/length of the column is 13.09m. The slenderness ratio in the y axis works out to be 202.98! The maximum allowed per the code is 180. Theoretically, the 2 interior columns failed.

I also checked the various connection joints, that too failed!

My client when informed of this ask “How come the structure is still standing?”

More on this in next entry. Do not want to bore people to much at one go.
Bye & happy engineering!

Steel Engineering - Deflection

Happy Belated Merdeka Day to all fellow Malaysians. This year’s celebration seems subdued and low-keyed compared to previous years. Considering the soaring prices of goods and rocketing inflation nowadays, this is to be expected. I hardly saw any cars decorated with mini flags this year and hardly any shops flying the National flag. Well all these “belt tightening” to cope with high price of goods and services can sure put a damper on everybody’s mood.

It was actually a double whammy for me this year. First, the escalating expenses together with the slowdown in business, and secondly, the news that a leader of the ruling party, allegedly labeling the Chinese as immigrants or squatters. Its a bit depressing, having been born here, grew up here, lived and worked here, and suddenly labeled a “squatter”.

Actually there is a third whammy. All I got from this year Budget is an increase in price of cigarettes, my one bad habit (although my wife will disagree that I have only 1 bad habit – ha! ha!)

Somebody once said, “Its easy to be A Malay hero, or a Chinese hero, or an Indian hero, but its difficult to be a Malaysian hero”. I guess its safe to conclude that Datuk Ahmad does not aspire to be a Malaysian hero.

The most disappointing aspect about the whole episode, is the Prime Minister’s response, which is akin to “Aiyo! Never mind-lah. I am sure he doesn’t mean it”. Wow, that’s that even close to a light slap on the wrist.

Some politicians are still playing the racial card, but despite their best (or worst) efforts, the people in Malaysia as a whole are still living and working in harmony. United we must be, to face the challenges and competition from other countries.

MY PRESENT JOBS

Attached with today’s blog, is a photo of a job in Nilai, which was completed recently. Note that when designing cantilever trusses, do remember to check for deflection and make sure the design meets the requirements as specified in the British code are complied with.

Below is an extract from BS5950 : Part 1 : 1985 on the deflections criteria there must be met. Note, imposed or service loads are just another word for Live Load. Live load is generally equals to 0.25 kN/m² for buildings in this country. (per Uniform Building Code, Laws of Malaysia).

BS 5950 : Part 1 : 1985

Structural use of steelwork in building

2.5.1 Deflection

The deflection under serviceability loads of a building or part should not impair the strength or efficiency of the structure or its components or cause damage to the finishings.

When checking for deflections the most adverse realistic combination and arrangement of serviceability loads should be assumed, and the structure maybe assumed to be elastic.

Table 5. Deflection limits other than for pitched roof portal frames.

(a) Deflection of beams due to unfactored imposed load.

Cantilevers	Length/180
Beam carrying plaster or other brittle finish	Span/360
All other beams	Span/200
Purlins and sheeting rails	See 4.12.2

(b) Horizontal deflection of columns in single-storey buildings

Tops of columns in single-storey buildings	Height/300
In each storey of a building with more than one storey	Height of storey under consideration/300

(c) Crane gantry girders

Vertical deflection due to static wheel loads	Span/600
Horizontal deflection (calculated on the top flange properties alone) due to crane surge	Span/500

NOTE 1. On low-pitched and flat roofs the possibility of ponding needs consideration.

NOTE 2. For limiting deflection in runway beams refer to BS 2853.

Steel Construction & Engineering

VIEW POINT OF AN ENGINEER

To start off, congratulations to Datuk Seri Anwar Ibrahim on winning the by-election in Penang. I think, some of the support he received was that people hope that he can help the economy. Basically a lot of people have lost confidence in the Government’s ability to manage the economy. He should take this opportunity to help find ways to alleviate the suffering of the people. Millions of Malaysians are struggling to survive after drastic increase in EVERTHING!

To both Barisan and Pakatan, please realize that people are so tired with all these politicking. Enough of all the allegations and counter allegations. High time to get back to work to find ways to help the people. The well being of the economy is what is truly important to the people. People have children to feed and bills to pay. I believe the party that manages to do this will surely win the next General Election.

CONSTRUCTION INDUSTRY

The construction industry was in the doldrums the past few months and it seems to be even worse now! Various construction related organizations have pleaded unsuccessfully with the Government to help stabilize the building material prices This is the first and much needed step to get the sector moving again. This will directly or indirectly generate much needed activities which will benefit the entire economy.

MY PRESENT JOBS

None to speak of. (ha! ha!). I submitted some roof framing (steel beams and columns made up of rectangular and square hollow section (RHS & SHS)) for a housing project in Puchong last week. Other than that, a meeting tomorrow on framing of laminated glass for IOI Building, also in Puchong. Anybody got work for me?

I have included a drawing of a job I was involved in a couple of months ago. The sketch was done using the “Sketchup” program. I did the steel drawings on Autocad which they require for submission to the authorities. The roof is supported by ‘curved’ steel trusses. Looks nice? By the way, this building is in Australia.

If only I can get more overseas job. Its’ really a win-win situation. I am sure we can do it at much lower costs compared to if its’ done locally (in this particular case, if its done in Australia). Got it done all via email.

Effective lengths of Compression Members

Here in Malaysia, the governing code is the British Standard, specifically BS 5950 : Part 1 for steel structures.

I had some questions from some engineers regarding effective lengths last week. So, maybe it would help to write out the specific clause on effective lengths per the British code.

Clause 19.6.2. Effective lengths of compression Members

BS 5950 : Part 1 : 1985 limits the slenderness permissible in struts to the following :

• 180 for members resisting loads other than wind loads
• 250 for members resisting self-weight and wind loads
• 350 for members acting as a tie but subject to lad reversal under wind action.

The slenderness ratio, which is the effective length divided by the radius of gyration, is used to determine the axial capacity of a structural member.

Hope the above is of use to you. Anybody needs further clarifications, please let me know.

Till the next time, Happy Engineering.

VIEWPOINT OF AN ENGINEER

ECONOMY

Whew! Finally some good news. The PM has announced that he will stepping down (but only in 2 years time). My first reaction is, “Its too long”. However, maybe this long transition is good. Hopefully this will stop the politicking and the Honorable leaders will get down to work, which is helping the people. Millions of citizens are suffering caused by the steep price hike. Besides, as a friend mentioned a new leader does not mean things will get better – could be even worse. All we can do is hope and pray.

Please come up with better ideas than telling people to sell “goreng pisang” after they are done with their day job. Those that are doing this full time are already struggling to make a living! Having extra competition from part-timers does not help. Probably only guarantee losses for all involved!

Another bright idea is paying civil servants twice a month. Maybe I am stupid, but I can’t figure out how this will help the people involved. Unless they are thinking the people couldn’t be trusted with their money and this prevent them from spending all in a couple of days upon receiving their salaries.

Wonder, who comes out with all these ideas?

CONSTRUCTION INDUSTRY

The construction industry is seemingly in a coma. A common respond I get nowadays is, “Project on hold, as budget exceeded” “How to quote, prices now like the stock market” etc. Until the prices of building material prices are stabilized, there is no hope of recovery. I can’t understand why the Government never thought about all this, before they happily hike up the fuel prices.

I applaud the initiatives of the Master Builders’ Association suggestion that the Government stockpile certain materials to stabilize prices. Whether this works or not, nobody knows, but at least its an attempt to stabilize prices and get the construction industry moving again. Its been said that the construction industry has the biggest multiplier effect on a country’s economy (maybe, I am biased).

MY PRESENT JOBS

1) Bungalow at Bukit Damansara

I am working on a bungalow in Bukit Damansara but only on the structural steel portions only, namely the car porch, the staircase and the roof top (which consists of cantilever columns supporting a ‘wavy’ roof structure – tough!) However it’s a creative concept, they even plan to have a ‘koi’ pond on one of the upper open levels and a steel bridge! The owner is an established and successful architect with his own company.

2) Training

I provided some training for the technical staff of a roof truss manufacturer in Klang last week. Basically it’s a training on “How to design a roof truss (using RHSs & SHSs) and its connections”. Design is based on BS5950 , which is the governing code for Malaysia. Considering, that this is my first time I am doing this, I think I did not do too badly. I am quite sure, most of them were still awake when I was through – ha! ha! Anybody, interested in Steel Design training?

CONSTRUCTION INDUSTRY & THE SUPERNATURAL

Not going to talk much about politics or the economy. Depressing stuff. So how about a little ghost story…

CONSTRUCTION INDUSTRY & THE SUPERNATURAL

I have been working in this industry for a long time. I have heard a lot of stories about strange happenings related to this industry. Some believe that this is so because spirits stay in isolated places like trees, abandoned houses etc and when these types of places are cleared for development, there’s when we encounter those from the other side. Whether this theory is true or not, I do not know, but I admit that I personally have experienced some things that is hard to explain.

Anyway, a client dropped by last night. After the usual moaning about the state of the construction industry, he related to me, the strange encounters he had in the site that he is working in.

He is currently working, renovating an old and large colonial bungalow near the border of Selangor and Negeri Sembilan. That place must have been abandoned for a long time as the garden was overgrown with weed the height of a man. Most of the paint on the structure has peeled off and what remained has turned mildew yellow. The wooden framing for doors and windows have long gone missing except for small decayed portions of the frame.

The present owners wanted to spruce up the place so that they can attempt to sell it. He managed to secured this project which was basically to fix that place up.

He stationed 3 of his Indonesians workers there including an old portable cabin placed within the compound. The cabin was intended for the workers to stay in and also to be used as a mini office.

However, two days after that, he received the desperate call from his workers’ that they do not want to work anymore. Fuming, he rushed down there from his Cheras office/house. His workers refused to say anything except that they do not want to stay there. As a compromise, he booked a room in a budget hotel at the nearest small town, a couple of km away. They were willing to work there during day time provided they leave by 6pm.

A few days after that, after dinner one night, he realized he left some drawings at the cabin which he needed for a meeting. He drove down there, and got there just before midnight. As he was exhausted he decided to spend the night there at the cabin.

He woke up in the middle of the night as he thought he heard some sound. However, after listening for a while and not hearing anything he decided to go back to sleep. Just as he was about to doze off, he again heard something, this time he barely but was sure he heard children crying. Puzzled he went out to check but the crying stopped and everything seemed normal. He finally managed to force himself to fall asleep.

Early the next morning, he met up with his workers to instruct them what to do that day. Just before leaving, he decided to climb up the scaffolding to the platform on the second floor to inspect on the work done. After he was on the platform, he noticed a few sets of footprint on the platform. Nothing really special about it except for 2 things. It was made by someone who was bare footed and it was about half the size of an adult foot print!

He quickly erased those foot prints thinking there must be some explanation. No point scaring his already jittery workers and jobs are so hard to come by come by.

On his way out, he stopped by a small roadside stall, at the “main” road. The stall was run by an old Malay lady in her sixties or seventies. As she brought over his drink she asked whether he is working at that old place. He briefly told her that he is renovating that place. The old lady nodded and said, “Jaga. Tempat kotor” (Be careful. Place is dirty). Further attempts to obtain further information was met with a smile and the shake of the head. Finally, when finally paying his bill he attempted one last question asking what the place was used for originally. With a sigh she sat down and told him that a long time ago, when she was just a little girl, that building was used as an orphanage. One night it caught fire…and most of the children were killed.

Coincidence or what? I don’t really know.

Steel Connection Design

I have written a little previously on bolt shear. I was going to was planning to write about plate bearing. However, on second thoughts, I think most of us had a tough and worrying week. So I won’t bore anyone with the technical stuff. I will continue with this the next time.

So have a good weekend and happy Engineering.

CONSTRUCTION INDUSTRY – STILL QUIET

As millions of Malaysian struggle to eke out a living, the political drama continues. I have read some of the comments given by SAPP for their decision include, flip-flop positions, fire fighting due to poorly conceived plans, economic incompetence etc.

Let’ say even if all these are true, wouldn’t any action against the ruling party now create more instability to the economy. As it is now, people are already lost and confused no thanks to the gigantic increase in fuel prices and the resulting increases in prices in almost everything. In the end, it’s the lower and middle class people (the majority of the citizens) who will suffer most.

Arguably, the most common answer an MP (all parties) gives when asked why he/she is in politics, and chances are they will reply, “To serve the Rakyat.” Well. For once, do it! Work together now (ALL political parties), if they still want, slug it out when things are better. What we need now is stability.

Steel Engineering – Connection Design

This is a continuation of the Support Truss that I was doing previously. Since, it has to be connected to Reinforced Concrete (probably to the beam or column) the usual methods are either 1) Cast-in bolts or 2) Chemical bolts.

Can’t include a sketch, as I noticed the sketches (done originally in Microsoft Excel) that I inserted earlier did not come out properly. Can anyone help me with this?

Basically Cast-In bolts are inserted into the timber formwork before the beams or columns are concreted. The protruding threads (say 50mm protrusion) connects to pre-punched plates that have been welded to the truss.

As for chemical bolts (example Hilti, Ramsett etc) are special bolts that are used after RC beams or columns have been casted. Holes are drilled into the concrete and these bolts are then inserted breaking a seal which releases certain chemical which bonds the bolt to the concrete.

Anyway, I have a stand alone program that calculates bolt shear, bolt bearing, plate bearing, welds, bolt tensile capacity and good things like that. All these are designed based on the British Code, BS5950. (Must see how I can improve that software now that I have more free time).

Please note that there are 2 common types of bolts, Grade 4.6 and Grade 8.8. The different grade has different shear strength. The formula for calculating the shear capacity is : Ps = ps x As , where ps is the shear strength ( 160 N/mm² for Grade 4.6 and 970 N/mm² for Grade 8.8). As is the tensile area of the bolt.

Similar there are 2 common different grades for steel plates, Grade 46 and Grade 50.

HOW TO GET BY

I got to think ways how to get through this downturn. Remember, for always every disaster, there are always opportunities. Think out of the box. Not merely increasing productivity but more ideas that one can do. A successful friend once told me, that there is no law that dictate that a person can’t get rich during the worst recession. Just can’t rely on the Government to improve things. More about these the next time.

STEEL ENGINEERING – Truss Design

Surprise announcement by SAPP today, guess they are not too happy with the present Government. I think I should clarify that I am neither pro-Government nor pro-Opposition. I support whoever that strive to improve the lives of the ordinary people.

However, I think any further stability now would only worsen the economy. Please, its time for everyone (especially ALL the political parties) to unite and work together to get the economy moving again. At the very least, they should at least postpone their quarrel until things get better. Serve the people, the lower and middle-class is struggling to make ends meet.

TRUSS DESIGN – STEP BY STEP SUMMARY

· Determine the nodal coordinates to model the truss.

· Determine the Uniformly Distributed Loads and apply it to truss. (based on Live, Dead & Wind Load)

· Run Analysis

· Check maximum axial and tensile forces in members.

· Check selected members for their axial and tensile capacity. (dependent on area, radius of gyration, unbraced length etc)

Remember, in Malaysia, we have to comply with the British Code – BS5950.

Voila! – we are done. Easier than baking a cake, right? (I have been watching a lot of those cooking shows on TV).

Got to cut this short as I still have to work on the connection design. That is how to connect the truss to the RC beam. More on that the next time.

In the meantime, happy Engineering & take care.

STEEL CONTRUCTION

Well, its’ another new day. I do try to have a positive outlook each day, with thoughts like, I might get a new project or maybe I will be paid. One can always hope, right?

News still dominated by the fuel hike. Bad news is petrol has exceeded US139 a barrel. The good news is Saudi Arabia plan to increase their output.

I applaud the Government in their efforts to alleviate the sufferings of the people through cash rebates, petrol card plan etc. However, it seems they are doing it in a haphazard way. I wonder whether they conducted a thorough study and planning before the petrol hike.

The biggest fear I had when I heard about the increase was not so much the actual increase in price but more how it will adversely affect the economy. Unfortunately, that nightmare has come to pass as the Construction (can’t really comment about the other sectors) sector has slowed tremendously.

I sincerely hope the Government fully concentrate on reviving the economy (not measures by cutting their entertainment allowance by a whopping 10%)

TRUSS ANALYSIS

I sent the following sketch to my client today to clarify on the actual dimensions. Without this information I am unable to proceed with the design of the support truss.

The actual design is not difficult. However, sometimes the actual clarifications etc is a bit time consuming.

Project :	SUPPORTING TRUSS FOR SCAFFOLDING							Date :
Bldg :
Item :
						Design Loads
					?
	RC Slab ?
	?
?
	Need Dimensions.
	Based on the diagram above, the structure is unstable. Only 1 point of support. Is if possible to use the following
				?
	RC Slab
	?
?
	Add Strut		OPTION 1

More on the above support truss once I have the dimensions.

So happy Engineering & take care.