www.sefindia.org

STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

 Forum SubscriptionsSubscriptions DigestDigest Preferences   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups  RegisterRegister FAQSecurity Tips FAQDonate
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log in to websiteLog in to websiteLog in to websiteLog in to forum 
Warning: Make sure you scan the downloaded attachment with updated antivirus tools  before opening them. They may contain viruses.
Use online scanners
here and here to upload downloaded attachment to check for safety.

Some general view
Goto page Previous  1, 2, 3 ... 55, 56, 57 ... 65, 66, 67  Next
 
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion
View previous topic :: View next topic  
Author Message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sat Jul 24, 2021 6:11 am    Post subject: Reply with quote

ECONOMY CONSIDERATIONS BY STR DESIGNERS

In preceding posts , the generosity AND high heartedness of Structural designers has been discussed for sake of AESTHETIC considerations.  But Structural engineer task is manifold in nature . apart from safety , and aesthetics , he has to ensure that proposals are economical too.

Economic considerations as given hereinbelow:

1.0 FOUNDATIONS. -
These are chosen based on soil bearing capacity , depth of foundations  and Gravity loading. But the focus is to provide economical foundations. First choice is Isolated footings , then combined , and lastly raft in selection of shallow foundation economy wise . If soil strata is not suitable , deep foundations in form of piles is needed which are costly but all efforts are made in the direction of eco proposal.
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sat Jul 24, 2021 6:25 am    Post subject: Reply with quote

ECONOMIC CONSIDERATIONS BY STR ER

2.0 MIXED (SEMI- FRAMED ) STRUCTURES
The residential /school / other buildings are either planned as LOAD BEARING on brick walls OR FRAMED STRUCTURE comprising of rcc columns and beams with brick walls as filler walls. In a quest to achieve economy , the designer is inclined to go for mixed design involving inner walls as load bearing and outer walls as framed to allow for  large openings in these outer walls. The walls are load bearing with proper stepped footings , and where columns are introduced , these are on rcc footings based on gravity load shared by them.
However in notes , it is clearly stated that all walls are Load Bearing and Any Walkie any portion of wall shall not be removed /disturbed. This way economy is achieved in the project.
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sat Jul 24, 2021 7:50 am    Post subject: Reply with quote

ECONOMIC CONSIDERATIONS BY STR ENGINEERS

3.0 DETAILING OF REINFORCEMENT  -
It is the sincere endeavour of Structural  Designer to curtail / reduce reinforcement at locations where it is not required to reduce steel consumption in the project .
In simply supported beams , few bottom bars not exceeding 50% , are curtailed at about  0.10  L from span.
Top reinforcement at continuous supports , are required upto 0.30 L from support face. Some  designer provide only minimum two nos 12 mm dia bars in central 0.40L portion + LD on either side,  unless higher top reinf is needed from midspan BM compression aspect .

Even stirrups are provided  five zones , one central 0.50L , and two zones of 0.125L on each side , to detail stirrups in quest to provide economy to large span beams by the structural designers.

No body wants to give credit to such designers for their sincerely, it is pity.

(to be continued)
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sat Jul 24, 2021 8:13 am    Post subject: Reply with quote

ECONOMIC CONSIDERATIONS BY STR ENGINEERS

4.0 DETAILING OF REINFORCEMENT - RCC columns
RCC  columns are designed with loads and moments  for establishing reinforcement , the designer always like to reduce the Reinforcement as it moves to upper floors  , generally , every two floors in a multistorey building columns. This is also an economic consideration and seen in all drawings of structures.

5.0 DETAILING OF REINFORCEMENT - SLABS
Slabs reinforcement is generally shown in plan . The curtailment / cranking up of Reinforcement bars and extent of detailing in an endeavour to achieve economy is evident from structural drawings showing slab reinf details in plan.

Structural engineers's efforts are never complimented .
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sat Jul 24, 2021 1:49 pm    Post subject: Reply with quote

ECONOMIC CONSIDERATIONS BY STRUCTURAL DESIGNERS

6.0 BRIDGE DESIGNS  -
Bridge designs are the best example for designers efforts in proposing economical, constructible , structurally safe and environmentally aesthetic structures .
The combinations and permutations are done in design office  based on various studies  to arrive at most economical proposal without compromising other above stated requisites. The final proposal is a result of complex  calculations , brainstorming  and precise decision making by Bridge Structural engineers.

Bridge Structural Designers are the best economical design developing engineers.
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sun Jul 25, 2021 3:18 am    Post subject: Reply with quote

DURABILITY CONSIDERATIONS BY STR ER

In preceeding postings , some cases of Aesthetic  , economic considerations are highlighted , there could definitely be more such cases .

Durability of structures is the essence of a  civil engineering development so that Structure could able to live its intended life . All efforts on QUALITY ASSURANCE  during Construction are aimed to achieve one goal , i.e. Longevity of structure . Durabe construction is the combined efforts from all concerned , be at site , PMC , design. The QA starts from Design office itself .

Few examples of QA concern , durability related considerations are enumerated hereinbelow :

1.0 NOTES , INSTRUCTION IN STRUCTURAL DRAWINGS  -
Providing important notes , specific instructions in str drawings is the first step by Structural designers towards Quality Assurance. Notes regarding concrete mix , steel reinf grade , clear cover, Lap length , brick quality , brick mortars etc are given as part of design basis BUT Durability /QA instruction notes like Minimum cement content in conc mix , maximum aggregate size , Lap staggering , CURING (timely and fully) , camber instruction , Electrical /Plumbing / Internet / gas line conducting/sleeves instructions , References and much more , are given in structural drawings indicating  the intent / concern of structural engineer s on DURABILITY .

(to be continued)
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sun Jul 25, 2021 4:02 am    Post subject: Reply with quote

DURABILITY CONSIDERATIONS BY STR ER

2.0 PROVIDING HIGHER THICKNESS  IN OH TANK  ROOF DOME
Generally those locations of structure which are exposed to extreme weather conditions and not easily accessible after construction to take care of maintenance needs later dates, are judiciously provided with higher thickness than that required from design considerations , especially in thin members.
Roof domes of OH tanks require very thin  dome thickness when designed . But providing 25 to 40 mm extra thick over and above design will take care of durability concerns , since 80 mm to 100 mm thickness as per design requirements , with poor inspection and difficult accessibility may not suffice , whatsoever possible quality control taken. This is a case of durability consideration by engineer.
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sun Jul 25, 2021 5:05 am    Post subject: Reply with quote

DURABILITY CONSIDERATIONS BY STRUCTURAL DESIGNERS

3.0 PROVISION OF CORROSION RESISTANT STEEL & SULPHATE RESISTANT CONCRETE
Though CRS & SRC are comparatively costly, their provision ensure structure durability . In coastal areas with aggressive environment , and in  soils chemically harmful , taking these measures along with epoxy painting helps to ensure structure longevity.
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sun Jul 25, 2021 5:39 am    Post subject: Reply with quote

DURABILITY CONSIDERATIONS BY STR ER

3.0 CANTILEVER REINFORCEMENT -
Cantilever slabs and beams require thorough check during design calculations as these are subject to higher BM wrt span . Normal as beam require BM = w*L^2 / 8 for udl but a cantilever beam require  FOUR TIMES for the same loading and span. As such ,the cantilevers reinforcement to be checked doubly design stage.

For slabs which have thin thickness and no stirrups to hold top bars in position unlike beams, there are always chances that top bars may not stand at desired position due to construction LL or otherwise , despite best QA efforts and provision of chairs. It is seen that some wise designers provide little extra reinforcement depending on status of  supervision . This is definitely a Durability concern from designers considering the holistic view .
Back to top
View user's profile Send private message
vikram.jeet
General Sponsor
General Sponsor


Joined: 26 Jan 2003
Posts: 3156

PostPosted: Sun Jul 25, 2021 5:59 am    Post subject: Reply with quote

Preceding post - Extra reinf provision in cantilever slabs

Some Consultants / & Structural engineers may not like to provide extra and stick to the calculated values.

But in my opinion , engineer  take the calculated values as guide and as lower bound values. But wisdom of designer shall not be slaved to the calculations only. Reasons for such extra provisions can always be recorded in the design.
In  Govt Organisations like CDO / CPWD , DDA DESIGN, & other Govt Undertakings , the engineers were refrained of providing extra as CTE / Tech Vigilance were there to vett  sample designs yearly to see excess Reinforcement provisions. But if reasons are mentioned , I think these were cleared.

Some Private Consultants ,  are wise to consider construction difficulties even at best QA and keep such provisions as design policy.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion All times are GMT
Goto page Previous  1, 2, 3 ... 55, 56, 57 ... 65, 66, 67  Next
Page 56 of 67

 

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


© 2003, 2008 SEFINDIA, Indian Domain Registration
Publishing or acceptance of an advertisement is neither a guarantee nor endorsement of the advertiser's product or service. advertisement policy