Suitable choice of stuffs and labor
Insitu support concrete and structural steel are popular and dominates in the bordering market of multi floor edifices. Through the above rating we found that the insitu support concrete frame ‘s stuffs and labor is reasonably much stable so steel and precast concrete frame. Therefore, we recommend utilizing insitu reinforcement concrete frame attack in this development.
Cost is one of the important factors need to be considered in the choice of structural framing options and this costs of framed constructions can be affected by the market status. Through our experience and market analysis, we found that the insitu support concrete frame is much cost efficiency compared to the others type of structural frame. This is due to steel is peculiarly volatile and ever influence by the exchange rates due to international competitions. Adversely, cement monetary value is more stable and harmonizing to ‘BCA ( 2007 ) ‘ , the statistic claims that the UK mean cement monetary value is stable over the last 10 old ages and it is raised below the rising prices rate. Cement is one of the chief constituents in the concrete mixture and therefore do the concrete monetary value by and large will be cheaper. Therefore it is sagely no to suggest steel frame as its monetary value fluctuate more often in comparing with concrete.
Speed of building
In rule, the insitu support concrete frame has a disadvantage in term of building velocity it is comparatively slow due to the clip consumed for bring arounding. However, lead clip for steel frame really is higher than insitu reinforcement concrete frame because one of the grounds is due to the steel frame need to pre-fabricate in mill and it is requires a figure of fiction procedures.
Lead clip can be defined as the existent clip counted from seting in an order ( by the builder ) until to the existent building one site of a peculiar component. Harmonizing to the “ lead clip figure published in the Chartered Quantity Surveyor ( 1992 ) , show that insitu support concrete frame ‘s lead times is 2-8 hebdomads and it is less than the steel frame ‘s lead times ; with 8-14 hebdomads ” . Hence, the insitu support frame building ‘s “ entire building clip ” would be shorter if compared to steel frame. Although steel frame building has an advantage in term of faster structural hard-on clip but in our sentiment the shorter ‘total building clip ‘ produced by insitu support frame building is more important. Therefore, the insitu support concrete frame building is more suited and is recommended in this undertaking.
Ability to standardize
The insitu support concrete frame is more flexible and tolerant in any change during the building procedure. Any sequel change is straightforward and it would non much affect the undermentioned building sequence, procedure, cost and significantly greater hold would non go on. But, both the steel and precast concrete frame has disadvantages in the ability to standardize. This is due to both are mill prefabricated merchandises and subsequently merely present to site for installing. Therefore any sequel change in steel frame or precast concrete frame building either in design or building sequence will do an impact in the mill production line every bit good as to the subsequent following building be aftering procedure.
The insitu support concrete frame has built-in fire opposition advantage compared to steel frame which fire opposition factor is non built-in. Therefore steel need extra fire protection work and this straight will affect extra building clip and cost.
Size and nature of site
As mentioned above both of the steel and precast concrete frame are prefabricated in the mill. Therefore, it has a disadvantage and restriction in bring forthing immense structural frame during the prefabrication procedure and installing procedure at site. Similarly the bringing procedure of prefabricated immense frame will besides tough and monolithic and non practical. But, this does non go on to the insitu support concrete frame where the immense structural elements can be adjusted and produced on site by building it in little portion each clip without affect by the factor of size and nature of site.
Finally we would wish to suggest that this 10 floor edifice to be constructed by utilizing insitu reinforcement concrete frame building due to the above mentioned advantages. In add-on, this insitu support concrete frame is more utile in carry throughing ‘green procedure ‘compared to steel frame. Adversely, we besides do non negligence on the disadvantages points of the insitu support concrete frame such as quality control, monolithic building procedure and etc. However, this insitu support concrete ‘s existing disadvantages factors can be reduced to an acceptable degree by following a proper site direction system and good planned building procedure.
- Construction Technology 5, Heriot-Watt University
- Comparison Of Reinforced In-Situ Concrete And Structural Steel In Multi-Storey Building Framework Construction, RIAD QUADERY ( ICE Membership Number: 64405090 )
- BCA ( 2007
- Chartered Quantity Surveyor ( 1992 )
Unit of measurement 1 ( degree Celsius )
In order to increase the edifice height to 30 floors, the old proposed construction demand to see and get by expeditiously to the gravitation tonss and resists important sidelong tonss or “ sway ” force cause by air current, while at the same clip, non showing inordinate ego weight tonss on the foundation system. Therefore, some change in footings of frame will necessitate to take into consideration for accomplishing the tall edifice design safety factor.
Harmonizing to “ Chew, Y L M. , Construction Technology for Tall Buildings ( 2nd Edition ) , the sum of stuffs needed in a tall edifice to defy gravitation tons is about additive with its tallness, nevertheless the sum of stuff needed to defy sidelong forces increases with the square of the air current velocity. ” The Figure 2.1 below is an illustration of the sidelong forces imposed by air current addition exponentially with the edifice tallness.
A ) Introduction of “ Shear Truss – Shear wall Structure ”
Shear walls usually is reflected to the perpendicular elements in the sidelong force defying system ( LFRS ) . This shear wall is really celebrated apply in many constructions. For conventional concrete frame system, shear wall is designed to work as a deep, thin perpendicular cantilevered beams members where it is robustly connected from the roof degree onto the foundations degree. While at the same clip the insitu reinforcement concrete floor are designed in robust connexion into the shear wall ( perpendicular component ) and executing the map as a horizontal stop to reassign sidelong tonss to the perpendicular component and later into the foundation. Please refer the below illustration of “ Diaphragm of Shear wall ( Figure B ) , ‘Shear Wall Action ( Figure C ) ‘ , ‘Diaphragm Action ( Figure D ) ‘ and
For this 10 storey office edifice, it is design with a symmetrical floor layout and this layout makes it appropriately to make few shear wall system. Furthermore this shear wall design and its execution will merely affect some minor agreement and structural design change, such as ;
- alter the type of foundation,
- change over the bing wall component go perpendicular support concrete wall,
- alter the floor system in order it must be robust plenty and able to reassign the sidelong force to the shear wall within the bound of design warp.
- Similarly the design of the beam ( underneath at unfastened infinite country ) must be stiffly tied into the back uping shear walls make certain the sidelong burden can expeditiously for transportation to the foundation.
With the above change the whole shear wall will be formed ( mention layout program grid line A-B/3-6 & A ; F-G/3-6 ) and this new created system non merely carries perpendicular burden but it floor system moving as a stop to reassign the sidelong tonss to this shear wall and so reassign those burden to the foundation expeditiously. With this alternate design the edifice tallness will able to accomplish 30 floors and upper limit to accomplish 35 floors height. Besides, through this attack the overall edifice construct will be remained unchanged.
B ) Introduction of Frame Using Vertical Trusses, Belt Trusses and /or Outrigger Trusses
This construct is development from the earlier shear wall. The intent of this design is to supply a perpendicular truss call ‘Outrigger Trusses ‘ where it is robustly connected to the margin column/exterior column with the intent to organize a much stiffer construction at external column and enables it to defy greater air current forces or other signifier of sidelong burden, every bit good as the resistant of gravitation burden. In add-on the ‘Belt Trusses ‘ will be built and it is working in wrapping through the margin column at the same degree as the outrigger trusses to farther stiffen of the construction.
This design is suited in apply to amend this edifice height into 10 floor. The Figure E and Figure F below shown two diagrams to exemplify the construct of this perpendicular trusses, belt trusses and outrigger trusses.
In order to use this construct in this undertaking, the margin edifice column ( facade column ) will be tied by utilizing beam act as outrigger trusses and robustly connected to cardinal nucleus ( besides act as shear wall ) . Through this alternate frame solution the whole construction will move as a big system will enabling a construction about 25 % stiffer than a original construction entirely trusting on a shear truss or shear wall system while without altering the floor program agreement. Figure F shown how the outrigger truss combine with shear wall to farther enhance this whole edifice construction to defy sidelong forces.
C ) Introduction of Tube System and Bundle Tube System
The tubing system has been the most efficient structural system used for tall edifice. This tubing attack creates a 3 dimensional system ( Refer Figure G ) . This system can be formed by utilizing the conventional frame system where the external columns around the margin of the edifice are designed in much closer together. Subsequently, these columns around the corners of the four edifice frontages are tied robustly with short beam and will organize a continuity system around all four frontages and efficaciously make a construction similar to a immense box subdivision that cantilevers from the foundation to the top of the edifice. This structural system capable in defying sidelong forces in any way as in rule a ‘Box ” subdivision has built-in strength.
This tubing system is appropriate to follow in order to increase this edifice height to 30 floors. From this edifice bing layout design ( in term of form ) it is appropriately to organize a ‘Tube form ‘ . Therefore, harmonizing to this tubing system design standards, the margin column ( facade column ) of this edifice will be placed much closer ( Refer Figure H ) and tied robustly by beam surrounded the four frontages of the edifice and go more stiffened. This will enable the whole construction act as a whole system to defy the sidelong force every bit good as working to reassign the gravitation burden to the foundation. The advantages of this tubes system is it is allow fewer interior columns, and so make more useable floor infinite.
In add-on the above propose tubing system can sagely complect or unite act as a whole with the bing tubing frames, i.e. two figure of lift nucleus and the option proposed new shear walls ( place at grid line A-B/3-6 & A ; F-G/3-6 ) , to make and execute another attack call ‘bundle tubing system ‘ . Through this combination a stronger construction will be created and expeditiously to defy the sidelong forces and gravitation tonss. The Figure F illustrate the package tubing system and through this integrate structural frame it is decidedly will go more expeditiously to resists sidelong tonss or “ sway ” force cause by air current.
As a decision, with the above solution of alternate frame design ( i.e shear walls, perpendicular trusses, belt trusses and Outrigger Trusses, tubing system ) . This edifice will be able to increase to 30 floors height with any one of the above individual alternate frame design. However it is advisable to unite those attacks by looking at the advantages and permission of this bing symmetrical edifice layout with the aim to resists important sidelong tonss or “ sway ” force ( cause by air current ) , every bit good as header expeditiously with the gravitation loads ( perpendicular burden ) . Furthermore theses combination will non do many alterations in footings of the original design and the edifice construct.
- Chew, Y L M. , Construction Technology for Tall Buildings ( 2nd Edition ) ,
- Construction Technology 5, Heriot-Watt University
- Brick Industry Association, Technical Notes 24C-The Contemporary Bearing Wall, Introduction To Shear Wall Design, ( Sept./Oct.1970 ) ( Reissued May 1988 ) www.gobrick.com
- Tall Building Structures Analysis And Design, By Bryan Stafford Smith, Alex Coull )
Double tegument frontages is really popular apply in many European metropoliss. This wall system is attractive due to its characteristic such as lastingness, ecology, greener engineering, aesthetical screening and etc. This dual tegument frontage able to supply natural airing into a edifice infinite and besides can cut down energy ingestion. These dual tegument frontages sometimes besides referred to as a ‘building in edifice ‘ .
This wall system can be define as a traditional individual frontage doubled indoors or outside by a 2nd, basically glazed frontage. Each of these two frontages is normally called a tegument. Each of the facade tegument can be constructed by assorted different combinations of stuffs, normally by two tegument of glazed. However, it is besides popular to use an outer bed of glass used together with a solid inner tegument. The country between the two teguments can name ‘ventilated pit ‘ or ‘air infinite ‘ . It is intentionally in such designed for perpendicular air circulation intents. The ventilated pit between the two teguments can be in assorted breadths, usually range from every bit narrow as several centimeters to as broad as several meters ( in order to organize accessible pits ) . The pit breadth will act upon the manner that the frontage is maintained. This air circulation infinite can be used in many different maps, but in the simplest analysis, the air will be drawn into the edifice by using the circulation utilises stack consequence, so that a natural airing consequence will be created for the internal infinite of the edifice. However, this pit infinite in some other design can be consists of fan supported or automatically ventilated.
A ) Natural Ventilation
The design of exterior portion of the tegument organizing a protective shield for the edifice and through the circulation utilises stack consequence the natural air will be drawn into the internal infinite of the edifice, so that a natural airing consequence will be created. Therefore, the interior comfort would non be affected even though the Windowss maintain unfastened throughout the whole twenty-four hours.
B ) Promote Greener Technology
The natural airing for high-rise conditions comparatively will cut down air-conditioning tonss and therefore will understate the CO2 end product produced during the edifice operational stage. Harmonizing to the research, carried out by ‘Franklin Andrews, Professor Michael Wigginton of the University of Plymouth and Battle McCarthy ‘ , who represent the United Kingdom Department of Environment, Transport and Regions has shown that dual tegument edifices when compared to progress individual tegument edifice are capable to cut down 50 % of CO2 emanations within the cold temperate clime prevalent in the United Kingdom.
C ) Better acoustic insulation-improve noise protection
Besides improved the noise protection, this dual tegument frontage are capable to derive an first-class acoustic insularity magnitude even though under the Windowss unfastened status. The magnitude of the acoustic insularity is equal to that obtained in classical glass frontage with the Windowss closed status.
D ) Reducing heating energy demand
The air stored in the pit between the two teguments would be heated by the Sun rays particularly in winter clip. Therefore bettering both the heat-insulating maps of the frontage and its thermic public presentation and later will cut downing the warming costs.
Tocopherol ) Reducing chilling energy demand
Double tegument frontage can let for nigh-time chilling of the interior edifice with make the window in unfastened during dark clip and thereby decreasing chilling tonss of the edifice ‘s HVAC system. Therefore particularly, use during summer clip the dark chilling can cut down the edifice energy ingestion peculiarly the costs of air-conditioning in the summer.
F ) Exploiting solar power
Both energy ingestion and costs are possible to cut down by use the Sun ‘s energy peculiarly with the incorporation of photovoltaic glass. By this method, the air stored inside the pit will be heat by the solar beams and cut down the energy ingestion.
G ) Increased Natural Daylighting
The dual tegument frontage will better the entree of natural light transmittal into the edifice infinite and therefore will bring forth a better indoor comfort and give positive consequence to residents wellness and every bit good as addition the productiveness of office forces. Physically with this increased natural daylighting will do a important cut down in the sum of electrical lighting required because the quality of visible radiation from natural daytime is more discriminatory to electrical lighting.
H ) Fire Escape
For some of the widest pits ( usually width scope from 600mm to maximum 2m ) , located between the two teguments will be able to supply a fire flight during fire occur. Therefore, with this dorsum up exigency flight will enable the fire brigade to salvage more life during there is fire to the edifice.
The above have indicated the benefit of dual tegument frontage wall and do it derive a batch of popularity throughout the universe.
- Construction Technology 5, Heriot-Watt University
- Franklin Andrews, Professor Michael Wigginton of the University of Plymouth and Battle McCarthy
Coursework Unit 6 ( B )
The proficient challenges that would necessitate to get the better of to bring forth a dual tegument frontage for this edifice are as below ;
1 ) Overheating challenges
The overheating job may go on particularly on warm twenty-four hours where hot air will roll up and emerge at the top air infinite and this may do the top floor offices suffer due to this overheating issue cause by this accretion of hot air in the pit. Therefore, technically approach to get the better of this job is to plan the ‘air infinite ‘ . There are two type of air infinite,
- undivided air infinite, and
- divided air infinite.
The undivided air infinite will has advantage from the stack consequence. On warm yearss hot air collects at the top of the air infinite and with the appropriate gaps at the top of the pit, therefore will syphon out warm air and at the same clip the replacing of ice chest air is draw in from the exterior.
The benefit of divided air infinite design is it can cut down over-heating peculiarly on upper floors. It is besides can cut down noise, fire and fume transmittal within the division. Furthermore, this floor-by-floor divisions add building simpleness of a reiterating unit and in bend can bring forth economic nest eggs.
From the above, indicate that both air infinite utilizing the natural natural philosophies principals ( hot air rises ) to pull air upward. We need to foreground that the 2nd type ; i.e. divided air infinite by floor is practically use for fire protection and sound transmittal intents.
2 ) Care Challenges
Although some of the edifice which is use the to the full glazed dual tegument frontage to accomplish an aesthetical pleasing position but its care is critical in footings of cleansing procedure. The air infinite demand to be cleaned more often because this country is tend to emerge of dust atoms which is circulates rapidly during the airing procedure. From an research carried out by ‘Terri Meyer, Associate Professor, school of Architecture, University of Waterloo ‘ indicate that glazed dual tegument facade demand to transport out full cleaning on a regular basis from 2 to 4 times a twelvemonth.
Therefore, the air infinite ‘s design standards need to see the imparts of cleansing particularly for the uninterrupted pit. Similarly, others barrier elements such as louvres placed within the pit must be removable in order to ease entree during cleaning procedure. Normally a device called boatswain ‘s chair platform which is similar to the window rinsing rig is used to entree the interior infinite of pit for cleansing intents.
In some dual tegument frontage design an ‘open gratings ‘ will be put at floor by floor or at peculiar topographic point act as the cleansing agent standing platform and without affected the airflow design.
For divided air infinite or pit, usually the interior Windowss will work as the entree panels for In some cases, where the pit is more divided, the interior Windowss, whether operable care intents. Therefore the design of air infinite need a consideration to supply an equal infinite for care intents besides the airing functionality. The interior clear dimension for air infinite is normally range from 600 to 900 millimeters.
2.2 ) Replacement of Deteriorate Mechanical Part
The high-tech machinist which is incorporated for the operation of dual tegument frontage ( peculiarly in airing procedure ) tend to hold a higher failure rate and fix cost. The same mechanics besides necessitate higher replacing costs. For cases, the replacing of wiring after a certain figure of old ages. Therefore, a preventative checking is need to transport out often in order to observe any mechanical job in an earlier phase before its give a negative impact onto the airing system. Besides, a proper information record and operation manual on those relevant mechanic device besides need to be keep properly. Through this information any instances of malfunction of mechanic device would be able to happen the direct causes and the solution can be carry out every bit shortly every bit possible every bit good as in happening the suited trim portion replacing within a shorter period of clip.
3 ) Control of Natural Ventilation
For high-rise edifice with dual tegument frontage, usually will establish a job on how to command and keep its natural airing ( here mean the quality of air ) to its resident. The country between the dual tegument frontage in rule is non affected by high speed air current because this country have been protected by the exterior tegument. Therefore, this part typically will entree by the dwellers for natural airing and this will do some unexpected impact of sound, fume, noise or heat transportation over this zone either from one subdivision, degree or room to the propinquity country. In order to extinguish these impact expeditiously usually this ‘buffer zone ‘ will be propose in compartmentalize design and separate into parts with air supplied by wickets or blowholes at the single zone or each degree. Then with the usage of blowholes or wickets allows for the control of the incoming air by cut downing air speed, every bit good as protecting from the rain and cut downing the noise transmittal from the outside. Regular cleansing procedure besides necessitate to be carried out in order to do certain that the ventilated air is ever in good quality such as out of dust atom. Hence, tower block edifice is basically need to be after and implement this control in order all its resident will be provide with a natural airing.
4 ) Fire Regulation
Although the air infinite between the teguments can be usage for fire flight but the fire ordinance might do troubles if no excess attending is provided. Therefore, for safety measured a proper indicant of fire flight path have to supply and topographic point at suited location at each floor.
5 ) Reduce of Space
As mentioned earlier the breadth of the pit can be formed from few centimeters until few metres. So, this will do some cut down in the edifice useable infinite. Therefore, it is important to happen the optimal pit breadth in order to derive an optimal office infinite in this edifice.
6 ) Climate
In some European state the dual tegument frontage will confront the climate issue such as humidness. For those dual tegument frontage associate with the inactive design schemes, ( i.e. thermic mass ) and beaming ( hydronic ) system, the condensation control will go an issue. Therefore, this critical factor demand to be solved in order it would non give a negative comfort consequence inside the edifice. This job can be technically solved by following condensation control through the appropriated mechanical ventilated system, i.e. ‘extract air system ‘ . This system usually use for location where the natural airing is non possible ( due to it locations built-in with high noise, air current and smoke ) . Through this system the fresh air will be supply by HVAC and it is precludes the natural airing. These systems tend non to cut down energy demands as fresh air alterations must be supplied automatically. In add-on, the residents are advisable non to set the temperature even though belong to their single infinites. However, the precedence consideration will still be put on the possible usage of natural airing. For cases, to come out a desirable hours of natural airing scheduled through the utilisation computerise control system can accomplish this aim.
7 ) HVAC Technically Design
The HVAC will play a major function for the edifice where the natural airing is non suited due to its negative clime conditions. Therefore, in instances the functionality of a HVAC system will go a important point and it will give an impact onto the edifice airing system. So, in order to work out that job, during the earlier design procedure demand to to the full integrates architectural and mechanical concerns is need to to the full integrates during the earlier design procedure. By this earlier phase planning will able to accomplish a smooth operation of HVAC system. In economical point of position it will less dearly-won and it is a wise planning because the cost economy figure is adequate to counterbalance for the building cost of the 2nd frontage.
8 ) Solar Heat Gain
This point come to the issue of inordinate of the incoming solar radiation above the comfort degree particularly in the summer clip. So, in order to keep solar heat addition under a standard design degree is by forestalling the heat from ab initio come ining the infinite. Particularly for a extremely full glazed edifice, usually an external shading devices are the most efficient agencies of cut downing solar heat addition. However, this external shading devices need to be cleaned often in order its can work efficaciously.
In the other attack is to utilize the particular glazing such as ‘spectally selective glazing ‘ and where this glazing stuffs is able to react otherwise to assorted wavelengths of solar energy or in other agencies is to allow seeable visible radiation while rejecting unneeded unseeable infrared heat. An ideal spectrally selective glazing permits merely the art of the Sun ‘s energy which is utile for daylighting.
Another type of glass called ‘electrochomic glass ‘ besides able to better the solar public presentation. The type of glass able to alter its coloring material from clear to dark utilizing electrical current. The electrical current can be activated in two ways, either by manually activated or by sensor reaction to the light strength. In physic rule dark coloring material glass will cut down solar transmittal into the edifice. Adversely when it is small sunlight, the glass will execute brightens in order to allow more suns beam into the edifice and minimized use of unreal visible radiation.
Both of the above mentioned stuffs is really practically use for the full glazed dual tegument high rise edifice. Besides, the application of horizontal blind can allow usage of daylighting and at the same clip still can accomplish the exterior position and it is a more economic attacks.
9 ) DSF Self Loading Transfer.
This dual tegument frontage ( DSF ) particularly full glazed type, is unable to take its ain burden. Therefore, the dead burden and imposed burden of teguments have to transferred to the next structural wall and frames. Therefore, the design of structural wall and frames need to see to transport the frontage skins lading.
10 ) Installation Process Challenges
His installing procedure is hard particularly for full glazed dual teguments facade because it is tough to work with the addition of the edifice tallness. Besides encounter near girls and possibility of the jeopardy of falling. Besides the air current blast is ever a inquiry of safety to its installer. Furthermore the are merely limited motions in the on the job topographic point. Therefore, the design of ‘open gratings ‘ to set at floor by floor to move as the installer standing platform is advisable and can ease the installing procedure.
From the above, we have analysed the possible proficient challenges of the dual tegument frontage for this propose 10 floor of office. Therefore, the undertaking design squad demand to see that proficient challenges during the earlier phase of design in order to come out a proper and efficient dual tegument frontage constructing design in footings of aesthetical pleasing and care capableness.
- Construction Technology 5, Heriot-Watt University
- Terri Meyer, Associate Professor, school of Architecture, University of Waterloo