Forming towers fast keeps time on side

With new structures popping up on a weekly basis it is of little surprise that the formwork suppliers are having a busy year. This looks set to continue as Jumeirah Beach Residence alone will be another 40 towers, Burj Dubai will climb into the record books, and more shopping malls continue to be developed. Construction Week investigates the challenges.

  • E-Mail
By  Colin Foreman Published  June 22, 2004

Forming towers fast keeps time on side|~|Formwork Body.jpg|~||~|A number of large projects have begun to emerge out of the ground this year. Structures have been built on the Palm Jumeirah and Dubai Healthcare City, buildings continue to be added to Dubai Marina, work on the 40 towers of Jumeirah Beach Residence is set to start, and structural work on the tallest of them all, the Burj Dubai, looks set to begin later this year. Much of this work is the result of last year’s efforts to secure contracts. “We have been very busy this year. We are particularly busy on the engineering side, as we now have to follow up on all the projects that are now coming on to site,” says Geir Gj. Jensen, general manager, Doka. For suppliers the challenge is now longer just signing contracts, it’s meeting them. “I think everybody is struggling to keep up,” says Ken Saxby, managing director, RMD Kwikform Middle East. Naturally such a booming market is now attracting suppliers hoping to gain a piece of the action to the market. “There are too many projects at the moment for the few formwork suppliers in the market and a number new players are now coming into the market,” says Jensen. Despite demand being strong, price is still a major issue. “Contractors want the bells and whistles but they want the lowest cost too,” says Saxby Like margins, deadlines are also tight. Building handovers are typically set at the beginning of a project but early design negotiations often run over time impacting on valuable programme time later on. By the time the superstructure is being built time often has to be caught up making already difficult programmes even harder. The programme becomes even tighter when suppliers actually design the formwork as well. “Our work is a little more than just supplying formwork. Anyone can do that. The package is very important. The basic price is one thing, but when you are buying a lot of material it needs to be followed up with all the required shop drawings,” says Jensen. The amount of design work required depends on the contractor involved. “When dealing with more professional contractors they will go into more detail and tell you exactly what is required and ask for suggestions. That is the end of the market we prefer to work in, because we can tailor make solutions,” says Saxby. “We have supplied a lot of custom-made formwork in recent years where we actually make a steel form to suit the customer’s specific requirements. It is often more economical for a contractor to have a custom made solution because it is quicker to use,” adds Saxby. Quality is also a major issue as consultants have become stricter than they were in the past and now often expect suppliers to inspect formwork before horizontal elements are cast. This is necessary to make sure that the material has been erected based on the certified drawing and it is able to take the loads it is designed for. Obviously this requires a physical presence and with so many sites it is a challenge to be everywhere at once. Manpower is also a concern on the contractor’s side. There is a shortage of skilled manpower because much of the labour now being brought in is poorly trained. “Special training is needed before formwork can be operated. I am sorry to say there are a lot of unskilled labourers and they are not able to do it,” says Jensen. Skilled labour is particularly important in areas where more complex systems are needed. For example, single sided formwork is used against piles in a basement the casting items have to be positioned in the right place, and workers on site need to know where. Material shortages are another problem that the industry has to contend with across the board, and for formwork the price of steel has been a particular concern. “There is a shortage of equipment in the region and combined with the recent increase in steel prices there has been a shortage of steel as well,” says Saxby. Although steel prices do not affect the price of existing material, equipment shortages have meant that suppliers have been forces to invest in new kit, exposing them to climbing steel prices. “Some people say formwork suppliers should not be affect by the material prices because they already have the material. Of course that is not true. You have to increase that stock, replace that stock when it is damage onsite so we have been affected by the increase in steel prices worldwide,” says Jensen. Steel is not the only material rising in price. “Even materials that you don’t necessarily relate to shortages have been affected. The price of timber has shot up by 25% over the last 12 months,” says Saxby. For some suppliers exchanges rates have also been an issue. Formwork produced in the Euro Zone has been greatly affected by the weakness of the US dollar and the dirham. This placed even more pressure on prices. Despite these pressure on prices quality can’t be sacrificed, and specifications must be met. “We are not joking when we are talking about climbing up buildings that are over 40-50 floors, safety really has to come first,” says Jensen. However, safety is not the sole responsibility of the supplier. Formwork suppliers should provide material that is produced to strictest quality controls, help train workers to use it safely, but they should not have to baby-sit the contractor. It is the responsibility of the contractor to follow the necessary procedures correctly. “For tall buildings huge structures are hung of relatively small items embedded in the concrete. It all depends on an exact execution by the contractor. This is particularly true for Dubai with its numerous multi-tower developments and super tall buildings. For tall buildings there are a number of formwork options available. For the normal horizontal slabs table forms are used. The only real variations being used are larger table forms that can shift 20 m2 in one go for the bigger buildings. This reduces the time needed for the slab formwork. The challenge is to keep up with the core that can advance far quicker than the slabs. “The core can easily climb every third day. If you achieve a four-day cycle for the slabs you are very fast. Traditionally, the slab rises in cycles of seven days. Two main formwork options are available for the construction of the vertical structures. One is a crane-climbing system and the other is a self-climbing system. Both use brackets that climb the structure ready for the next pour. The difference is how the systems climb. A crane-climbing system uses a tower crane to lift the brackets whereas a self-climbing system uses a built in hydraulics system so that it can lift itself saving on valuable crane time that can then be used for lifting the slabs. For many projects crane time is limited because there is little available space on the core. The calculation for the contractor is how much will it cost to use a self climbing system compared to the price of one more crane, and as buildings become taller the cost of a crane increases. Another option used locally is slipform. This system is typically used for silos or chimneys and climbs continuously in one go. It is used in the UAE for building cores, but has to stop periodically so that the slabs can catch up. “There is a trend for using slipform systems for one reason or another, I personally don’t see the benefit,” says Jensen.||**||

Add a Comment

Your display name This field is mandatory

Your e-mail address This field is mandatory (Your e-mail address won't be published)

Security code