marcus_a_j
Senior Member
I noticed that too. PCL is using that area for offices i think 'cause i saw some desks with blueprints and renderings, etc.
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I noticed that too. PCL is using that area for offices i think 'cause i saw some desks with blueprints and renderings, etc.
Edward
Senior Member
How does using steel versus concrete make a difference on the quality of the cladding?
The United Church came from a merger of the Methodist Churches and some Presbyterian ones, and as half the Presbyterian churches in Canada seem to be named St. Andrew's, there a good chance that one was Presby before it went United.
There is a picture of BCE/Brookfield under construction in the passageway that connects Union Station to the Skywalk, which I wandered by this Saturday, and where I noticed that BCE/Brookfield IS a concrete core-steel frame building. Caltrane's right.
42
caltrane74
Senior Member
Steel
4/4 = 100% awesome for all the steel skyscrapers in Toronto
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Concrete
1/ 2000 = .005 % Not bad, but I will admit Scotia Plaza is amazing.
Steel isn't used much in Toronto, but when it is used it has a perfect record compared to concrete.
Redroom Studios
Senior Member
I think we are both partially correct... apparently the construction style here was a sort of hybrid:
" The Canada Trust Tower is made up of reinforced concrete columns as part of its loading system and also has a composite steel deck with a concrete topping that allows for a live loading of 100 pounds per square foot."
(extracted from the following article)
Canada Trust Tower
Toronto, Canada
Structural Analysis I
December 12, 2005
Owner
The creation of The Canada Trust Tower began with a massive redevelopment of downtown Toronto. A noteworthy 5.5-acre block flanking the Royal Bank and Commerce Court, near the historic Dominion of Canada Building, and kitty-corner to the Union Station was chosen to be the gateway into the financial district of downtown. Bell Canada Enterprise’s branch: BCE Development Corp. obtained a 99-year lease on the site and planned BCE Place. The plan for BCE Place was initially going to cost more than $350 million; and be a combination of two major towers, 13 historic buildings that survived the great Toronto fire of 1904, and a shopping district. The first phase of the development was the 53-story Canada Trust Tower, and the second phase was going to be a 49-story Bay of Wellington Tower. Problems soon arose after planning when the immense size of these two buildings in one small area violated Toronto’s density and housing stock regulations. Instead of sacrificing the size of the towers, BCE financed the preservation of the 13 historic buildings, donated $12 million for assisted housing, included a day-care center in the complex, built a tunnel to Union Station, and provided space for the Hockey Hall of Fame.
Over the beginning of the construction of the phase one, cost rapidly increased and BCE Development Corp. crumbled into debt. After striking deals with other corporations BCED Corp. shifted primary ownership of BCE Place into the hands of its subsidiary Brookfield Properties. Brookfield Properties owns more than 50% of BCE Place with smaller ownership into the hands of OMERS Realty and Truscan Property Corp. By the end of the completion of the BCE Place in 1992, the final cost tipped the scales at just over $1 billion, which would be equal to $1.9 billion in 2005.
Construction of the first tower in BCE Place began in the spring of 1988. The plan for the 53-story landmark building was to offer more than 1.2 million square feet of office and retail space. A major feature of the tower was a modern trading floor which would draw major investment dealers of bonds, currency and non-stock trading. As construction was initiated in 1988, BCE was pleased to know that more than 40% of the first tower was pre-leased; and by near completion in 1990, 63% had been pre-leased. One of these major initial tenants of the property was Canada Trustco Mortgage Co. of Ontario, which claimed a piece of the ownership in the first phase, and granted the name Canada Trust Tower to the building.
Though the initial leasing of the Canada Trust Tower was exceptional, there were major concerns in the vacancy rates in the Toronto area. In 1989, over 9 million square feet of office space was created in the metro areas surrounding Toronto. The inclusion of the CT Tower added another 1.2 million square feet. This surge in space had occurred all through the 80’s and nearly doubled the office space in Toronto to reach 133.2 million square feet. Concerns about massive vacancies quickly ensued after the Towers completion. Brookfield Properties was not worried since they attract major financial and professional corporations that have high credit ratings and hold long-term leases. Brookfield is even growing while the neighboring buildings are feelings the pressures of the flooded market. With falling renting prices, BCE Place’s location and premier recognition has attracted corporations to take advantage of these rates and relocate there.
Brookfield Properties has successfully guided the Canada Trust Tower as well as BCE Place through the 90’s. At the start of the millennium the Toronto skyline saw a major change as the signature red sideways ‘C’ atop the Canada Trust Tower spire was replaces by a green ‘TD’ sign. Toronto Dominion Bank paid $8 billion to takeover Canada Trust. The tower still retains the name Canada Trust Tower, but its prime tenant is now TD-Canada Trust. This new entity now rivals Royal Bank as the country’s largest bank.
Through the past five years Brookfield Properties has effectively built itself into a powerhouse with nearly $14 billion in assets and through 75 properties in North America. The company was just slightly outbidded in the pursuit for ownership of the World Trade Centers in April 2001. Today, BCE Place is one of Brookfield’s most prominent assets, and continues to dominate the skyline and downtown district of Toronto. Canada Trust Tower has blue-chip tenants like CIBC World Markets, William Mercer, Marsh McLennen, and TD-Canada Trust. Brookfield Properties has a strong hold on the future financial stability of Toronto and Canada with their ‘A-class’ tenants and long-term leases.
Architect
The architecture of the Canada Trust Tower was a compilation of efforts from three different architects: Santiago Calatrava, the famous Spanish architect; Skidmore, Owings, & Merrill, LLP, the world renowned architecture firm based out of New York and Chicago; and Bregman & Hamann Architects, one of the leading architecture firms in Canada. Although Santiago Calatrava is mentioned as one of the architects associated with the Canada Trust Tower and the BCE Place, his architecture contributions were made only to the Galleria. The Galleria is an upscale shopping mall, which joins the Canada Trust Tower to all of the other buildings that make up BCE Place. Two architectural firms – Skidmore, Owings, & Merrill, LLP and Bregman & Hamann Architects – who joined forces for this project, designed the Canada Trust Tower. Skidmore, Owings, & Merrill, LLP is an internationally known architecture firm. They have worked on buildings such as the Sears Tower and the John Hancock Center in Chicago, and are currently working on the Freedom Tower, which is to replace the World Trade Center Towers. Bregman & Hamann Architects is one of the leading Canadian architectural firms. They have worked on numerous projects in Canada, specializing in mixed-use urban complexes. These types of facilities include commercial office buildings, hospitals, laboratories, airports, and broadcasting centers.
The Canada Trust Tower has a very contemporary style. The objective of Bregman & Hamann Architects was to create a building that did not simply end at the top, as most skyscrapers do. The Canada Trust Tower has many setbacks (see Figure 1) that give the roof a pointed appearance, as opposed to the flat top appearance that many other tall buildings have. Jagged rooflines and exteriors made of stone and glass are typical features of postmodern buildings, which is the architectural style of the Canada Trust Tower.
The main architectural material of the Canada Trust Tower is Rockville Pink, flamed finish granite. This granite covers the entire exterior of the tower and is visually different from most, due to the color. Another material that is used throughout the Canada Trust Tower is a low-E coated window. These, tinted green, windows are cased in aluminum and double-glazed to reduce energy costs for the building. These windows have good insulating properties, which reduce heating and cooling costs during different seasons of the year. The materials used at the Canada Trust Tower aren’t that unusual from other skyscrapers, but minor adjustments in color give the building a totally different look.
The egress and fire safety issues of the Canada Trust Tower were taken into consideration greatly by the architects. There are many standard safety features that were designed and constructed throughout this skyscraper, but there are also some high technology safety features. The tower has two emergency exits per floor, which are clearly marked and lead to exit stairwells that have an average width of 7 feet. These stairwells are in compliance with all egress safety codes. There are also Emergency Voice Communication (EVC) speakers located on each of the 53 floors, which communicate with the public in emergency situations. The fire safety system is comprised of fully automatic smoke detection and fire alarms, which are monitored by a computerized system. Overall, the Canada Trust Tower meets all standards and has quality egress and fire safety systems in place.
The Canada Trust Tower is one of the most aesthetically appealing buildings in the world. It is designed as a circular shaped building, but is put together with square shaped surfaces. This would be comparable to trying to build a cylinder out of legos – it would end up very jagged. The pink granite walls, combined with tinted green windows give the tower a very unique look as well. The top of the Canada Trust Tower sets this skyscraper apart from all of the others in Toronto, due to its many setbacks. These setbacks provide for 12 corner offices with spectacular views of the city on most floors near the top of the building. The Canada Trust Tower, although not one of the tallest buildings in the world at 51 stories, is aesthetically one of the more exceptional skyscrapers.
Structural Engineer
The structural engineering firm that was involved in the design and construction of the Canada Trust Tower at BCE Place was Yolles Group Inc. Yolles was founded in 1952 and has established itself in numerous building sectors including commercial, sports, retail, and residential. Some of Yolles more notable projects include One Canada Square at Canary Wharf in London (this is the tallest building in the United Kingdom), the World Financial Center in New York, and the Air Canada Building in Toronto. In December of 2004, Yolles Group Inc was acquired by Halcrow Group Ltd. The two companies merged to form Halcrow Yolles which currently has principal offices in Toronto, New York, London, and Dubai. Halcrow Yolles is currently involved in such projects as the design and engineering of the Lester B. Pearson International Airport terminal redevelopment in Toronto, the British Embassy in Moscow, and the Trump International Hotel and Tower in Toronto.
The main structural framing system in the Canada Trust Tower at BCE Place is a tube-in-tube system (see Figure 2). The creation of the tube-in-tube system has been credited to the famous engineer Fazlur Kahn, who while he worked for the world renowned firm of Skidmore, Owings, and Merrill, had the opportunity to have a hand in the design of such world famous buildings as the John Hancock Center and the Sears Tower. The main idea behind a tube-in-tube structure is that there are two tubes in the building, an exterior tube that handles almost entirely vertical loading, and an interior tube that handles almost entirely lateral loading. The exterior tube carries the gravity loading to the foundation through the numerous columns that line the exterior of the building. The interior tube handles the lateral loading due to winds, or in extreme cases, earthquakes by using the interior tube as a shear wall. A shear wall acts as an extremely large cantilevered column with an extremely large bending stiffness that is considerably larger than that of the columns that make up the exterior tube of the structure. The Canada Trust Tower is made up of reinforced concrete columns as part of its loading system and also has a composite steel deck with a concrete topping that allows for a live loading of 100 pounds per square foot.
Because of the use of a tube-in-tube system to carry the loading of the building, the Canada Trust Tower is able to have completely column free office floors. This feature makes the Canada Trust Tower a very attractive location for companies because they have flexibility in the setup of their office space due to the fact that they wouldn’t have to design around columns in the middle of their office space. Another unique structural feature of the building is that each floor contains 12 corner offices. This allows the owner of the building more opportunities to rent out these more sought after properties within the building. The existence of the 12 corner offices not only give the owner this ability, but along with it comes the feature that the normally harsh winds that form around the base of a skyscraper are dissipated due to the angled circumference of the building. Normally with a box shaped skyscraper, winds will strike the flat surface of the building and get forced down towards the ground, where they combine with the wind from below and create an extremely large gale by the time it reaches the ground. Through wind tunnel tests that were done on models of the various designs of the Canada Trust Tower, the engineers were able to reduce the amount of wind that occurs at the base of the skyscraper.
MEP Engineer
High rise buildings cause many difficulties in the design process of mechanical systems. Dramatic changes in pressure due to elevation and temperature differences must be considered in the design process. The mechanical system should be designed to use minimum space as to maximize rentable floor space to tenants, but should also be able to handle the capacity needed for the building, be properly incorporated into the structural system, and be able to account for movement during operation and use. The Mitchell Partnership, a firm founded in Toronto, was the main firm involved in the design of the mechanical system of the Canada Trust Tower.
The heating ventilation and air conditioning (HVAC) portion of a tall building can cause many problems, especially when the building is located in a cold climate. A phenomenon called the stack effect is especially prevalent when the difference between the outside and inside air temperature is large. The stack effect is a draft of air going from the top of the building to the bottom due to a massive pressure difference. The massive temperature difference between the inside and the outside that occurs, especially during the winter months in Canada, causes higher pressure on the outside of the building than the inside. Due to the rising of hot air in the building and a large change elevation, the pressure at the top of the building becomes very low. The high pressure cold air quickly flows through the building, often through an elevator shaft or HVAC systems, to the bottom of the building and out openings in the building.
This problem can be mitigated with a combination of different methods. Creating a tighter building with enclosures around elevator shafts and rotating doors can help prevent the high flow of air. Also, providing excess inflow air supply to floors on the lower portions of the building and excess exhaust to upper levels can help reduce pressure differences between floors. In the Canada Trust Tower the HVAC system is designed for very extreme temperatures ranging from -10ºF during the winter to 90 ºF during the summer. The fresh air system provides 40 ft3 per minute per 200 ft2 of outdoor air per worker. In addition, each level provides separate compartmental control, keeping the levels relatively tight.
A design difficulty with HVAC systems in large office building is meeting the needs of a variety of tenants. The Canada Trust Tower has a separate cooling mechanism for each floor so the tenant can adjust the temperature for their particular needs. The air runs through ductwork in the ceiling from variable air volume (VAV) boxes on the floors that provide differential cooling to the floor based on need. VAV boxes are provided with information of the surrounding room temperature and can cool the area based on that information (see figure 3 for illustration of how VAVs work). VAVs can drastically save in energy costs because the correct amount of cooled air is directed to the place of greatest need.
The design of the electrical system of the Canada Trust Tower was led under the expertise of Mulvey & Banani International Inc. The electrical distribution system runs through the suspended ceilings nine feet above floor level. The building is designed so an in-floor distribution system can be installed. The emergency power system is operated by diesel generators that would start immediately in the case of an outage. The generators will operate some elevators and emergency lighting in addition to continuing much needed air circulation.
Many aspects of the design of the Canada Trust Tower help to reduce energy costs. The glass for the windows is a green tinted low energy glazed sealed glass to reduce energy loss. A Digital Direct Control (DDC) system is in place to create the most efficient system for heating and cooling. DDCs can sense existing conditions of the floor and allow for rapid control of building environment with reduced error. The variable air volume boxes also help in reducing energy consumption by providing heating and cooling to the places of greatest need on the floor. The base heating and cooling system is continually running in order to save energy in the start up of the system when tenants need to be running their systems often.
In order to conserve energy and reduce waste, Brookfield Properties has multiple programs to help tenants be more earth friendly. Project Blue is a program that encourages recycling of paper and ink cartridges and energy saving initiatives for tenants. Through a program called B.E.S.T. (Brookfield Energy Savings for our Tenants), energy audits are performed by Brookfield Properties to determine who is consuming more energy than needed and provides assistance for tenants who need to reduce their energy use.
Construction Engineer
Professional construction management is a project management team which includes a professional construction manager and other individuals who are responsible for the comparison of systems of construction and their interrelationship; material handling and management including selection of cranes, hoists, and concrete pumps; on site observation and report on tall building construction. The practice of professional construction management includes:
· Working with the owner(s) and the A/E firms from the beginning and make recommendations on design improvements, construction technology, schedules and construction economy.
· Obtain materials and equipment.
· Coordinate all construction contractors, payments to contractors, changes, claims, and inspections for the design.
· Propose design and construction alternatives if appropriate
· Analyze the effects of the alternatives on the project cost and schedule.
· Monitor continuous development of the project to ensure that project cost and schedule are not exceeded without knowledge of the owner(s).
· Perform other project related services as required by owner(s).
The general contractor for the Canada Trust tower, responsible for coordinating all tasks on the job site, was PCL Constructors, Inc. Three general stages that they would have gone through for this project are the estimate stage, the monitoring and control stage, and the evaluation stage.
The estimate stage involves the development of a cost and schedule for the construction as part of the proposal. A systematic analysis of different conditions set by project design and by site characteristics are used to create a best estimate. The success of a contractor depends upon the accuracy of this estimate. It is used to obtain the job as well as make a large profit. The contractor must determine the best way to be successful in his/her commitment. It is a fine line to determine the best estimate. A high estimate would result in the loss of the job to a competing firm. A low estimate may win the job but result in a low profit. A contractor must keep in mind the possibility of changes to the project. Initial estimates are almost always rejected; a collective barraging process is done between the owner and the firm to determine a final bid.
In the monitoring and control stage of the construction process, the construction manager has to keep constant track of both activities' durations and ongoing costs. Weather and building conditions can play a big role in delay or postponement of jobs, which can lead to increased costs. Constant evaluation of the construction process is necessary until building is complete. As jobs are completed they are relayed to the contractor, the third stage can start.
The evaluation stage is the where results of a finished construction process are compared against the estimate. A contractor deals with this uncertainty during the estimate stage and only when the process is completed is she/he able to estimate the precision of the estimate. It is in this last stage of the planning process where the hypothesis is checked to see if they were correct. If they were not or if new constraints emerge, he/she should introduce corresponding adjustments in future planning.
Works Consulted
Ali, M. “Evolution of Concrete Skyscrapers: from Ingalls to Jin Maoâ€. 2001. http://www.ejse.org/Archives/Fulltext/200101/01/20010101.htm.
" The Canada Trust Tower is made up of reinforced concrete columns as part of its loading system and also has a composite steel deck with a concrete topping that allows for a live loading of 100 pounds per square foot."
(extracted from the following article)
Canada Trust Tower
Toronto, Canada
Structural Analysis I
December 12, 2005
Owner
The creation of The Canada Trust Tower began with a massive redevelopment of downtown Toronto. A noteworthy 5.5-acre block flanking the Royal Bank and Commerce Court, near the historic Dominion of Canada Building, and kitty-corner to the Union Station was chosen to be the gateway into the financial district of downtown. Bell Canada Enterprise’s branch: BCE Development Corp. obtained a 99-year lease on the site and planned BCE Place. The plan for BCE Place was initially going to cost more than $350 million; and be a combination of two major towers, 13 historic buildings that survived the great Toronto fire of 1904, and a shopping district. The first phase of the development was the 53-story Canada Trust Tower, and the second phase was going to be a 49-story Bay of Wellington Tower. Problems soon arose after planning when the immense size of these two buildings in one small area violated Toronto’s density and housing stock regulations. Instead of sacrificing the size of the towers, BCE financed the preservation of the 13 historic buildings, donated $12 million for assisted housing, included a day-care center in the complex, built a tunnel to Union Station, and provided space for the Hockey Hall of Fame.
Over the beginning of the construction of the phase one, cost rapidly increased and BCE Development Corp. crumbled into debt. After striking deals with other corporations BCED Corp. shifted primary ownership of BCE Place into the hands of its subsidiary Brookfield Properties. Brookfield Properties owns more than 50% of BCE Place with smaller ownership into the hands of OMERS Realty and Truscan Property Corp. By the end of the completion of the BCE Place in 1992, the final cost tipped the scales at just over $1 billion, which would be equal to $1.9 billion in 2005.
Construction of the first tower in BCE Place began in the spring of 1988. The plan for the 53-story landmark building was to offer more than 1.2 million square feet of office and retail space. A major feature of the tower was a modern trading floor which would draw major investment dealers of bonds, currency and non-stock trading. As construction was initiated in 1988, BCE was pleased to know that more than 40% of the first tower was pre-leased; and by near completion in 1990, 63% had been pre-leased. One of these major initial tenants of the property was Canada Trustco Mortgage Co. of Ontario, which claimed a piece of the ownership in the first phase, and granted the name Canada Trust Tower to the building.
Though the initial leasing of the Canada Trust Tower was exceptional, there were major concerns in the vacancy rates in the Toronto area. In 1989, over 9 million square feet of office space was created in the metro areas surrounding Toronto. The inclusion of the CT Tower added another 1.2 million square feet. This surge in space had occurred all through the 80’s and nearly doubled the office space in Toronto to reach 133.2 million square feet. Concerns about massive vacancies quickly ensued after the Towers completion. Brookfield Properties was not worried since they attract major financial and professional corporations that have high credit ratings and hold long-term leases. Brookfield is even growing while the neighboring buildings are feelings the pressures of the flooded market. With falling renting prices, BCE Place’s location and premier recognition has attracted corporations to take advantage of these rates and relocate there.
Brookfield Properties has successfully guided the Canada Trust Tower as well as BCE Place through the 90’s. At the start of the millennium the Toronto skyline saw a major change as the signature red sideways ‘C’ atop the Canada Trust Tower spire was replaces by a green ‘TD’ sign. Toronto Dominion Bank paid $8 billion to takeover Canada Trust. The tower still retains the name Canada Trust Tower, but its prime tenant is now TD-Canada Trust. This new entity now rivals Royal Bank as the country’s largest bank.
Through the past five years Brookfield Properties has effectively built itself into a powerhouse with nearly $14 billion in assets and through 75 properties in North America. The company was just slightly outbidded in the pursuit for ownership of the World Trade Centers in April 2001. Today, BCE Place is one of Brookfield’s most prominent assets, and continues to dominate the skyline and downtown district of Toronto. Canada Trust Tower has blue-chip tenants like CIBC World Markets, William Mercer, Marsh McLennen, and TD-Canada Trust. Brookfield Properties has a strong hold on the future financial stability of Toronto and Canada with their ‘A-class’ tenants and long-term leases.
Architect
The architecture of the Canada Trust Tower was a compilation of efforts from three different architects: Santiago Calatrava, the famous Spanish architect; Skidmore, Owings, & Merrill, LLP, the world renowned architecture firm based out of New York and Chicago; and Bregman & Hamann Architects, one of the leading architecture firms in Canada. Although Santiago Calatrava is mentioned as one of the architects associated with the Canada Trust Tower and the BCE Place, his architecture contributions were made only to the Galleria. The Galleria is an upscale shopping mall, which joins the Canada Trust Tower to all of the other buildings that make up BCE Place. Two architectural firms – Skidmore, Owings, & Merrill, LLP and Bregman & Hamann Architects – who joined forces for this project, designed the Canada Trust Tower. Skidmore, Owings, & Merrill, LLP is an internationally known architecture firm. They have worked on buildings such as the Sears Tower and the John Hancock Center in Chicago, and are currently working on the Freedom Tower, which is to replace the World Trade Center Towers. Bregman & Hamann Architects is one of the leading Canadian architectural firms. They have worked on numerous projects in Canada, specializing in mixed-use urban complexes. These types of facilities include commercial office buildings, hospitals, laboratories, airports, and broadcasting centers.
The Canada Trust Tower has a very contemporary style. The objective of Bregman & Hamann Architects was to create a building that did not simply end at the top, as most skyscrapers do. The Canada Trust Tower has many setbacks (see Figure 1) that give the roof a pointed appearance, as opposed to the flat top appearance that many other tall buildings have. Jagged rooflines and exteriors made of stone and glass are typical features of postmodern buildings, which is the architectural style of the Canada Trust Tower.
The main architectural material of the Canada Trust Tower is Rockville Pink, flamed finish granite. This granite covers the entire exterior of the tower and is visually different from most, due to the color. Another material that is used throughout the Canada Trust Tower is a low-E coated window. These, tinted green, windows are cased in aluminum and double-glazed to reduce energy costs for the building. These windows have good insulating properties, which reduce heating and cooling costs during different seasons of the year. The materials used at the Canada Trust Tower aren’t that unusual from other skyscrapers, but minor adjustments in color give the building a totally different look.
The egress and fire safety issues of the Canada Trust Tower were taken into consideration greatly by the architects. There are many standard safety features that were designed and constructed throughout this skyscraper, but there are also some high technology safety features. The tower has two emergency exits per floor, which are clearly marked and lead to exit stairwells that have an average width of 7 feet. These stairwells are in compliance with all egress safety codes. There are also Emergency Voice Communication (EVC) speakers located on each of the 53 floors, which communicate with the public in emergency situations. The fire safety system is comprised of fully automatic smoke detection and fire alarms, which are monitored by a computerized system. Overall, the Canada Trust Tower meets all standards and has quality egress and fire safety systems in place.
The Canada Trust Tower is one of the most aesthetically appealing buildings in the world. It is designed as a circular shaped building, but is put together with square shaped surfaces. This would be comparable to trying to build a cylinder out of legos – it would end up very jagged. The pink granite walls, combined with tinted green windows give the tower a very unique look as well. The top of the Canada Trust Tower sets this skyscraper apart from all of the others in Toronto, due to its many setbacks. These setbacks provide for 12 corner offices with spectacular views of the city on most floors near the top of the building. The Canada Trust Tower, although not one of the tallest buildings in the world at 51 stories, is aesthetically one of the more exceptional skyscrapers.
Structural Engineer
The structural engineering firm that was involved in the design and construction of the Canada Trust Tower at BCE Place was Yolles Group Inc. Yolles was founded in 1952 and has established itself in numerous building sectors including commercial, sports, retail, and residential. Some of Yolles more notable projects include One Canada Square at Canary Wharf in London (this is the tallest building in the United Kingdom), the World Financial Center in New York, and the Air Canada Building in Toronto. In December of 2004, Yolles Group Inc was acquired by Halcrow Group Ltd. The two companies merged to form Halcrow Yolles which currently has principal offices in Toronto, New York, London, and Dubai. Halcrow Yolles is currently involved in such projects as the design and engineering of the Lester B. Pearson International Airport terminal redevelopment in Toronto, the British Embassy in Moscow, and the Trump International Hotel and Tower in Toronto.
The main structural framing system in the Canada Trust Tower at BCE Place is a tube-in-tube system (see Figure 2). The creation of the tube-in-tube system has been credited to the famous engineer Fazlur Kahn, who while he worked for the world renowned firm of Skidmore, Owings, and Merrill, had the opportunity to have a hand in the design of such world famous buildings as the John Hancock Center and the Sears Tower. The main idea behind a tube-in-tube structure is that there are two tubes in the building, an exterior tube that handles almost entirely vertical loading, and an interior tube that handles almost entirely lateral loading. The exterior tube carries the gravity loading to the foundation through the numerous columns that line the exterior of the building. The interior tube handles the lateral loading due to winds, or in extreme cases, earthquakes by using the interior tube as a shear wall. A shear wall acts as an extremely large cantilevered column with an extremely large bending stiffness that is considerably larger than that of the columns that make up the exterior tube of the structure. The Canada Trust Tower is made up of reinforced concrete columns as part of its loading system and also has a composite steel deck with a concrete topping that allows for a live loading of 100 pounds per square foot.
Because of the use of a tube-in-tube system to carry the loading of the building, the Canada Trust Tower is able to have completely column free office floors. This feature makes the Canada Trust Tower a very attractive location for companies because they have flexibility in the setup of their office space due to the fact that they wouldn’t have to design around columns in the middle of their office space. Another unique structural feature of the building is that each floor contains 12 corner offices. This allows the owner of the building more opportunities to rent out these more sought after properties within the building. The existence of the 12 corner offices not only give the owner this ability, but along with it comes the feature that the normally harsh winds that form around the base of a skyscraper are dissipated due to the angled circumference of the building. Normally with a box shaped skyscraper, winds will strike the flat surface of the building and get forced down towards the ground, where they combine with the wind from below and create an extremely large gale by the time it reaches the ground. Through wind tunnel tests that were done on models of the various designs of the Canada Trust Tower, the engineers were able to reduce the amount of wind that occurs at the base of the skyscraper.
MEP Engineer
High rise buildings cause many difficulties in the design process of mechanical systems. Dramatic changes in pressure due to elevation and temperature differences must be considered in the design process. The mechanical system should be designed to use minimum space as to maximize rentable floor space to tenants, but should also be able to handle the capacity needed for the building, be properly incorporated into the structural system, and be able to account for movement during operation and use. The Mitchell Partnership, a firm founded in Toronto, was the main firm involved in the design of the mechanical system of the Canada Trust Tower.
The heating ventilation and air conditioning (HVAC) portion of a tall building can cause many problems, especially when the building is located in a cold climate. A phenomenon called the stack effect is especially prevalent when the difference between the outside and inside air temperature is large. The stack effect is a draft of air going from the top of the building to the bottom due to a massive pressure difference. The massive temperature difference between the inside and the outside that occurs, especially during the winter months in Canada, causes higher pressure on the outside of the building than the inside. Due to the rising of hot air in the building and a large change elevation, the pressure at the top of the building becomes very low. The high pressure cold air quickly flows through the building, often through an elevator shaft or HVAC systems, to the bottom of the building and out openings in the building.
This problem can be mitigated with a combination of different methods. Creating a tighter building with enclosures around elevator shafts and rotating doors can help prevent the high flow of air. Also, providing excess inflow air supply to floors on the lower portions of the building and excess exhaust to upper levels can help reduce pressure differences between floors. In the Canada Trust Tower the HVAC system is designed for very extreme temperatures ranging from -10ºF during the winter to 90 ºF during the summer. The fresh air system provides 40 ft3 per minute per 200 ft2 of outdoor air per worker. In addition, each level provides separate compartmental control, keeping the levels relatively tight.
A design difficulty with HVAC systems in large office building is meeting the needs of a variety of tenants. The Canada Trust Tower has a separate cooling mechanism for each floor so the tenant can adjust the temperature for their particular needs. The air runs through ductwork in the ceiling from variable air volume (VAV) boxes on the floors that provide differential cooling to the floor based on need. VAV boxes are provided with information of the surrounding room temperature and can cool the area based on that information (see figure 3 for illustration of how VAVs work). VAVs can drastically save in energy costs because the correct amount of cooled air is directed to the place of greatest need.
The design of the electrical system of the Canada Trust Tower was led under the expertise of Mulvey & Banani International Inc. The electrical distribution system runs through the suspended ceilings nine feet above floor level. The building is designed so an in-floor distribution system can be installed. The emergency power system is operated by diesel generators that would start immediately in the case of an outage. The generators will operate some elevators and emergency lighting in addition to continuing much needed air circulation.
Many aspects of the design of the Canada Trust Tower help to reduce energy costs. The glass for the windows is a green tinted low energy glazed sealed glass to reduce energy loss. A Digital Direct Control (DDC) system is in place to create the most efficient system for heating and cooling. DDCs can sense existing conditions of the floor and allow for rapid control of building environment with reduced error. The variable air volume boxes also help in reducing energy consumption by providing heating and cooling to the places of greatest need on the floor. The base heating and cooling system is continually running in order to save energy in the start up of the system when tenants need to be running their systems often.
In order to conserve energy and reduce waste, Brookfield Properties has multiple programs to help tenants be more earth friendly. Project Blue is a program that encourages recycling of paper and ink cartridges and energy saving initiatives for tenants. Through a program called B.E.S.T. (Brookfield Energy Savings for our Tenants), energy audits are performed by Brookfield Properties to determine who is consuming more energy than needed and provides assistance for tenants who need to reduce their energy use.
Construction Engineer
Professional construction management is a project management team which includes a professional construction manager and other individuals who are responsible for the comparison of systems of construction and their interrelationship; material handling and management including selection of cranes, hoists, and concrete pumps; on site observation and report on tall building construction. The practice of professional construction management includes:
· Working with the owner(s) and the A/E firms from the beginning and make recommendations on design improvements, construction technology, schedules and construction economy.
· Obtain materials and equipment.
· Coordinate all construction contractors, payments to contractors, changes, claims, and inspections for the design.
· Propose design and construction alternatives if appropriate
· Analyze the effects of the alternatives on the project cost and schedule.
· Monitor continuous development of the project to ensure that project cost and schedule are not exceeded without knowledge of the owner(s).
· Perform other project related services as required by owner(s).
The general contractor for the Canada Trust tower, responsible for coordinating all tasks on the job site, was PCL Constructors, Inc. Three general stages that they would have gone through for this project are the estimate stage, the monitoring and control stage, and the evaluation stage.
The estimate stage involves the development of a cost and schedule for the construction as part of the proposal. A systematic analysis of different conditions set by project design and by site characteristics are used to create a best estimate. The success of a contractor depends upon the accuracy of this estimate. It is used to obtain the job as well as make a large profit. The contractor must determine the best way to be successful in his/her commitment. It is a fine line to determine the best estimate. A high estimate would result in the loss of the job to a competing firm. A low estimate may win the job but result in a low profit. A contractor must keep in mind the possibility of changes to the project. Initial estimates are almost always rejected; a collective barraging process is done between the owner and the firm to determine a final bid.
In the monitoring and control stage of the construction process, the construction manager has to keep constant track of both activities' durations and ongoing costs. Weather and building conditions can play a big role in delay or postponement of jobs, which can lead to increased costs. Constant evaluation of the construction process is necessary until building is complete. As jobs are completed they are relayed to the contractor, the third stage can start.
The evaluation stage is the where results of a finished construction process are compared against the estimate. A contractor deals with this uncertainty during the estimate stage and only when the process is completed is she/he able to estimate the precision of the estimate. It is in this last stage of the planning process where the hypothesis is checked to see if they were correct. If they were not or if new constraints emerge, he/she should introduce corresponding adjustments in future planning.
Works Consulted
Ali, M. “Evolution of Concrete Skyscrapers: from Ingalls to Jin Maoâ€. 2001. http://www.ejse.org/Archives/Fulltext/200101/01/20010101.htm.
3Dementia
Senior Member
WTC was steel construction... not reinforced concrete... what if? No pancaking with concrete... from heat.
Redroom Studios
Senior Member
the demolition experts who buried the timed charges that brang them down would have just used bigger charges...
3Dementia
Senior Member
You are not making any sense.
Mongo
Senior Member
Redroom Studios is either being sarcastic, or genuinely thinks that the WTC attacks were faked, orchestrated by the US government. There are people who do think this -- often the same people who think that the US moon landings were also faked. In an attempt to remain civil, I will refrain from commenting on this "theory".
Bill
Bill
3Dementia
Senior Member
You mean there is no grassy knoll...?
So everything is faked? Thanks for the head up.
So everything is faked? Thanks for the head up.
Redroom Studios
Senior Member
I just like to stir things up! though, now that I think about it there were some strange shadows in the footage of the moon landing.... human psychology is a fascinating subject!
smuncky
Senior Member
wwII was a hoax
unimaginative2
Senior Member
Though I clearly believe the towers were brought down by terrorist-hijacked aircraft, people would have made the same dismissive comments about suggestions that the Gulf of Tonkin incident was fake or that Roosevelt knew Pearl Harbour was coming...
H
Hydrogen
Guest
Roosevelt knew Pearl Harbour was coming? He should have stopped it. It's really a horrible movie. Michael Bay is lousy director.
adma
Superstar
Was it over when the Germans bombed Pearl Harbor? Hell, no!
