Slim Floor Structures

Slim Floor Structures

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Tuesday, June 14, 2016

Innovative Foundation Walls by Read Jones Christoffersen


The east side of Toronto is currently one of the busiest areas for new condo construction in the city: over a dozen projects are reshaping the area’s skyline. One project in particular is using new technology for the construction of concrete buildings: Monde by Tucker Hirise. With 45 condo levels and 5 levels of underground parking, Monde is among the giants that are growing in the east. This unique project was designed by Read Jones Christoffersen Consulting Engineers and uses Peikko stud rail.


Design
Kumbo Mwanang’onze from RJC Consulting Engineers is the head structural engineer for Monde. ‘’The underground parking proved to be a challenge due to the earth pressure applying high shear forces on foundation walls’’ he explains. ‘’Earth density is usually 2000 kg per cubic meter. In the presence of ground water, the pressure on foundation walls rises considerably, increasing the shear force on walls at either side of the slabs ’’ points out Mwanang’onze. Because this site is located directly adjacent to Lake Ontario, the walls are designed on the assumption of the water-table being at ground surface. For a 5 storey underground structure, this pressure creates high shear forces on both sides of each suspended slab. Easy to install stud rails were specifically designed to resist these shear forces.



Installation
‘’Installing stud rails in our foundation walls is a simple procedure’’ says Maria Duzlevska Ilieva, site superintendent for Monde. The stud rails are installed in two steps: as one worker hangs each rail onto the wall reinforcement, a second worker ties it in position. ‘’Stud rails are installed at the rate of 30 rails per hour on average’’ explains Maria. Other options to deal with shear forces such as stirrups require more time to install.



Key stakeholders for the structure of Monde: 
RJC (Read Jones Christoffersen): structural engineers
Tucker Hirise: builder
Quadrangle Architects

Further details on the calculation of loads applied to foundation walls: 
The “Horizontal soil effective pressure p = K*(gamma(s)*h + q) where
o K=0.4
o gamma(s) = saturated weight of soil =10kN/m3 (NOTE: for saturated soil, the weight is equal to “weight of soil” – “weight of water”)
o h=height of soil above location of interest
o q = 12kPa vertical surcharge load at the surface.
Therefore @ ground surface (ie. H=0): p = 4.8kPa
Therefore @ bottom (ie. H=8): p = 36.8kPa
Water pressure = 80kPa
Total horizontal pressure = 36.8 + 80 = 116.8kPa

We would like to extend a special thanks to Kumbo Mwanang’onze who helped us write this article.


Friday, March 11, 2016

DELTABEAM FAQ

Deltabeam General Information


Why use Deltabeam?
Deltabeam allows to minimize the floor to floor height while maintaining long spans in both the slab and the beam directions. Since the system is mostly prefabricated it can be erected with a very small crew of installers. Deltabeam combined with hollowcore slabs is a great alternative to cast in place structures.

What are the savings that can be made with Deltabeam?
Compared to standard construction method, erection time and required labor is often greatly reduced. With Deltabeam slim floor design, the number of stories can be maximized for a same building height. Therefore, the price per square foot is greatly reduce. Additionally, the slabs spans can be increase, hence the number of column is reduce. Deltabeam's integrated fire resistance will often completely eliminate the fire proofing trade.

How many projects have used Deltabeam?
So far, over 10 000 projects around the world have used Deltabeam. Nearly 100 projects have been completed in North America since 2007.
o For more information on Deltabeam project please visit: http://references.peikko.ca/

When was Deltabeam first used?
The first project that used Deltabeam was built in 1989 in Finland

Who is responsible for the design of Deltabeam?
All Deltabeam are designed by Peikko’s engineers and Peikko is fully responsible for the design of its beams. Stamped and sealed shop drawings are part of Peikko’s offering. The EOR will be responsible for other elements of the building such as vertical elements (columns and walls), lateral stability (bracing, shear walls, diaphragm etc.) and foundations.

Who is responsible for the fabrication of Deltabeam?
Peikko has established a network of designated fabricators to produce Deltabeam. Peikko is responsible for the quality assurance of all its products. The selected fabricators are CWB and CISC certified.

Who is responsible for the detailing of Deltabeam?

Peikko provides its own shop drawing for every part manufactured. Here’s an example of a standard shop drawing produced by Peikko.

How does Deltabeam compare in cost with a steel wide flange or precast concrete beam?
A Deltabeam unit cost is approximately the same as a precast beam. Although the price for a steel wide flange beam may be lower than a Deltabeam per linear meter, Deltabeam will often lead to significant savings. For instance, Deltabeam's integrated fire resistance will often completely eliminate the fire proofing trade. Furthermore, lower floor to floor height will reduce cladding and heating & cooling costs. Also, reducing floor to floor height may allow for an additional floor for a given building height.

In which type of project is Deltabeam the most cost effective?
Deltabeam is usually the most cost effective when used in a rectangular (not square) grid layout. This way, hollow core slab spans can be maximized while reducing the number of columns. Deltabeam can optimize floor to floor height in any multi-storey building.



Deltabeam design and features


How far can the Deltabeam span?
Deltabeam has the best depth to span ration in the industry. The following table give an overview of typical span. Longer span than those presented in that table can be reached given that the beam can be deeper than the slab itself. Most of the time, Deltabeam's maximum span is limited to the hollow core slab span.

What is the optimal Deltabeam span and layout?

A rectangular grid layout is the optimal way to use Deltabeam. Where Deltabeam will be between 6m to 8m and hollow-core slabs would be between 8m to 12m.

How does Deltabeam achieve its fire resistance?
Deltabeam is ULC listed for 1, 2, 3 & 4 hours without requiring any fireproofing applied on the underside of the beam. The rebars inside the profile ensure that the beam has sufficient capacity under fire. The concrete inside the beam acts as a heat sink and slows significantly the rate at which the steel profile will rise in temperature.

Fire rebar shop installed inside the beam

Heat distribution inside the Deltabeam profile under fire condition

Whatch this video

Has Deltabeam ever been used in high seismic area?
Yes, Deltabeam have been used in project located in high seismic area such as Surrey(BC), Ottawa(ON) and Quebec City(QC).

Does Peikko provide design assistance?
From preliminary budget and layouts to construction site assistance, our engineering department will assist you thru the entire design process.

Can Deltabeam support steel deck?

Deltabeam can be use with a steel deck, hollow core slab or cast-in-place slab.

Can Deltabeam be designed as an edge / spandrel beam?

Absolutely, Deltabeam can be designed as an interior beam as well as an edge beam.

Can Deltabeam be designed with a cantilever?

Yes, Deltabeam already been designed for cantilever up to 2m.


Is Deltabeam produced with camber?
Yes, Deltabeams are manufactured with camber in order to respect the deflection limits specified in building codes. Both, ultimate state and serviceability state are taken into account.

Should I design with continuous columns or continuous beams?
Continuous beams give the opportunity to reduce beam dimension by using its negative bending moment resistance. Therefore, beam span will increase and overall beam weight may reduce by up to 20% .

However, since the entire load of the columns must be transferred through the beams, this type of construction is generally limited to 10 floors. Over 10 floors, continuous columns should be used.

Can Deltabeam be used with concrete columns or walls?

Yes, Deltabeam can be bearing either with a concrete column or wall. Peikko's PCs Corbel connection may be used to connect Deltabeam with vertical concrete elements.


Can Deltabeam be designed for point loads or non-uniform loading?
Absolutely, Peikko’s engineering department will gladly assist you with your specific loading requirements.

Has Deltabeam ever been used in a braced frame?

Yes, Deltabeam can be use in braced frame as well as in rigid frame.

What types of plates are used to produce the Deltabeam?
All plates used to manufacture Deltabeam meet the requirement specified in CSA G40.20 and G40.21 standards.

Can holes be made in the Deltabeam for conduits?

Yes, however these holes must be coordinated with Peikko’s engineering department.


How are curves handled with hollow core slabs and Deltabeam?

Deltabeam can accommodate virtually any shape. Deltabeam edge beams can be produced with an integrated formwork that can be straight, skewed or curved.


How much height can I save with Deltabeam?
Total height gain depends on floors load, number of stories and depth of the beams and hollow core slabs. Height gain is typically 400mm for 200mm hollow ore slab and up to 685mm for a 305mm deep hollow core slab.
How are cantilever balconies accommodated with Deltabeam?

There are two possibilities:

Cantilevering solid prestressed and precast slab:

Cantilevering the Deltabeam on the perimeter:




Connections


What are the possible connections with Deltabeam?
PCs Corbel welded to a steel column or casted in a concrete column can be used to connect Deltabeam to a column.

End plates can be added to a Deltabeam to weld it or bolt it to a steel column

Bearing surface such as top of a column or a wall can also be used as a connection

Deltabeam can even be connected to another Deltabeam by a side connection designed by Peikko.



Can Deltabeam to column connections be designed as a pin connections?
Yes, Deltabeam when connected with a PCs Corbel is consider as a pin connections since only shear stress will be transferred by the corbel to the column.

Can Deltabeam be designed as moment connections?
Yes, Deltabeam when connected by a welded of bolted end plate will act as a stiff connection which can transfer bending moment from the beam to the column. Continuous Deltabeam will also provide moment connections between the column and the beam.


Shoring


Why do we need to shore Deltabeam?
Since Deltabeam is cambered, it doesn’t need to be shored for deflection. The reason why we need to shore the Deltabeam is to prevent torsion on the side of the beam where hollowcore is loaded first:

Where do we need to shore Deltabeam?
The shoring posts need to be placed at both ends of the beam under the web. Shoring must be placed on the side of the beam where the hollowcore slab is loaded first.

What is the capacity of the shoring posts that are required?
The must be able to support the full weight of the hollowcore slab bay. Typically the shorting post used will have a capacity of 90kN.

Why do we not place any shoring posts in the middle of the span?
Since the beam is cambered, it is important to let the beam deflect during erection. If the Deltabeam is shored mid-span, cracking could occur when removing the shoring posts.

Is there a way to completely avoid shoring?
Yes. Deltabeam has a very high torsion resistance due to its closed trapezoidal shape so given that the columns and the connections can accommodate this high torsion during the erection the shoring posts are not be required.

How can I assure the structure is stable during erection? How is it braced?
Multiple systems can be used to brace temporarily the columns but we recommend using push and pull adjustable braces at least in the four corners of the building under construction as show below:
The braces can be secured in threaded holes at the top of the columns.


Grouting


When do I need to grout the erected floor?
Each floor should be grouted immediately after it is erected. A non-grouted floor provides no lateral stability and could collapse if multiple floors are erected without grouting.

In which order should I grout the components?
Usually the composite columns will be grouted first, then the Deltabeam and finally the hollowcore keyways.


The hollowcore keyways can be grouted at the same time as the columns and beams when using a grouting bucket.


This method can also avoid requiring a concrete pump truck

How deep does the grout need to go at the end of the hollowcore slabs?
The grout will only go inside the hollowcore slabs a few centimeters. The hollowcore slabs are provided with plugs at the end of the cores to prevent grout from flowing inside.

How do I block the underside of the beam before grouting?
The formwork needed to block the openings under the slab is very minimal as shown in the pictures below:
Formwork prior to grouting

Once formwork is removed



Ellisdon Uses Peikko Stud Rail on Toronto High Rise


Ellisdon is currently building a high rise project in Toronto named Foward condos, part of Concord Cityplace. The project involves a cast in place concrete structure which incorporates stud rail: a product increasingly used in Ontario. This specialized rebar is designed to take punching shear forces in a bi directional concrete slab as well as in concrete foundation walls. 


Kami Wilson is happy with the performance of Peikko on Cityplace: "Fast delivery: this was the most important factor in choosing Peikko" she explains. "It took 3 days from order confirmation to delivery: we issued our po on Friday January 15th and received the stud rails on Wednesday January 20th in the morning, before 10:30". Kami Wilson is a project manager working for Ellisdon Residential Inc. 


This is the second project with Ellisdon for Peikko. Other stakeholders involved in the project include: 

Architect: Page + Steele / IBI Group Architects
Structural engineer: RJC (Read, Jones, Christoffersen) 
Developer: Concord Adex
General contractor: EllisDon 
Stud Rail supplier: Peikko Canada






Monday, January 11, 2016

Composite Columns and Deltabeam used on Osisko Terraces

Composite columns and Deltabeam before the installation of slabs

An innovative structural system was used in northern Quebec last summer: a combination of specialized steel frame and hollow core slabs. The Osisko Terraces, a 4 story apartment building with 1 level of underground parking, was built with the Peikko frame. Consisting of composite columns and Deltabeam, the specialized steel frame provided an integrated fire rating and clear spans over 7 meters.  


Installation of hollow core concrete slabs

"We wanted a high quality system installed as quickly as possible" says Jean-Francois Brouillette, developer of the project. "With Peikko, we combined large bay sizes, integrated fire rating and fast construction". In detail, composite columns consist of tubular steel sections integrated with reinforced steel and filled with concrete onsite. These columns have the characteristics of both concrete and steel: small section similar to steel and integrated fire rating similar to concrete. 

Installed assembly: composite columns, Deltabeam and slabs

Through the use of Peikko structure, the Osisko terraces will reach an STC of 61 (Sound Transmission Class) and an IIC of 62 (Impact Insulation Class). The fire resistance being integrated in the structure, no additional fire protective material is required onsite. A few other details on the structure of Osisko:

- Typical bay sizes: 22’ x 30’
- Floor thickness: 10’’ hollow core and Deltabeam
- Composite columns diameter: 340 mm

Osisko Terraces: structure near completion

3D rendering courtesy of Trame architecture