Since l is a high-rise and ultra-high-rise tower crane construction of choice for lifting and transport equipment, paper describes the selection around the tower crane is required to properly solve several problems.
1. Regarding the choice of what kind of tower crane
Selected tower crane, the first is to select parameters appropriate self-elevating tower crane. In the various parameters, the most important thing is the main parameters: amplitude, since the most significant weight and lifting height. However, in determining the main parameters, but also determine the choice of what form the Crane: Yes, within the climbing tower crane, or attached tower crane; is pitching luffing boom tower crane, or car to bracket the level luffing crane.
Experience has shown that, 1 40 t * m-level functions within the climbing tower crane on a platform capable of reaching 80 t * m-level attached tower crane functions. With attached tower crane be equipped with more standard tower sections, and to be equipped with the necessary amount of attachment of the anchor rod and the corresponding parts. Therefore, to save the starting one-time investment, choose climbing tower crane within an economic and reasonable. However, in order to ensure safety in production and to obtain the best efficiency, should be prepared to climb inside the tower crane used for hoisting construction organization design and structure of the crane after the completion of the demolition program.
At present, the domestic self-elevating tower crane, mostly car level luffing jib tower crane jack-up, only a small number of factories producing small quantities of pitch luffing boom tower crane. Therefore, from a supply supply point of view, in order to choose the level of jib crane is more convenient. However, in high-rise buildings such as the forest environment, they must attack first to build a tower-to high-rise buildings, the pitching luffing boom tower crane Naishi a reasonable choice. Because you can tilt freely strut boom, boom neither the sky in the neighboring high-rise buildings waving, it would not collide with the surrounding high-rise buildings. Because of boom-type self-climbing tower crane with the above-mentioned characteristics, the Hong Kong Bank building under construction, using six sets of boom-type self-climbing tower crane. For the same reason, some Southeast Asian countries in recent years have introduced a number of moving from China's boom-type self-climbing tower crane for the use of high-rise building construction.
2. To buy or rent tower crane tower crane
Buy a Taiwan 120 t * m-class tower crane will require some 1.1 million yuan, for a building contractor in terms of not a small sum. Moreover, in addition to interest, the month must pay the driver, maintenance mechanics and electricians wages, bonuses, as well as power, fuel and spare parts. After completion of the project, but also the entire machine shipped to a base storage and maintenance, which in turn requires a degree of expenditure.
Rent a platform crane's advantages is that: (1) No need to specifically responsible for the care of the tower crane, the tower crane driver, maintenance and repair services by leasing companies; (2) the tower crane market advance and retreat, as well as warehousing storage, maintenance, etc. Service does not need to interfere. That is to say, as long as the monthly pay the high rents they can get the desired hoisting service, regardless of the other can be.
On the calculation of rent on the tower crane, so far there is no uniform regulations to follow, here are two different method of calculating monthly rent tower crane.
The first is return on investment law (Interest on Capital Outlay).
120 t * m-class tower crane, arm hinge point of the root height 80 m, boom length 50 m, priced 1.1 million yuan, service life of 8 years of work for 10 months.
(1) crane one-time investment 1.1 million yuan;
(2) The annual interest rate of 12%, 8 years total 1.056 million yuan of interest;
(3) The Annual Depreciation Rate Of 10%, 8-Year Depreciation Total 88 Million;
(4) Years Of Maintenance Fees By 10%, 8 Years Expenditure Total 88 Million;
(5) Insurance, Operation, Management, Miscellaneous Expenses An Annual Rate Of 5%, Totaling 440,000 Yuan;
(6) 8 Years After The Salvage Value 200,000 Yuan;
The other Baugerate France.
120 t * m-class tower crane, arm hinge point of the root height 80 m, boom length 50 m, priced 1.1 million yuan, service life of 10 years of work for 9 months.
(1) crane one-time investment 1.1 million yuan;
(2) months of interest and depreciation rate of 1.5%, 10-year total of 1.98 million yuan;
(3) The management of Maintenance and Repair of miscellaneous expenses 1.1%, totaling 1.089 million yuan;
(4) 10 Years After The Salvage Value 150,000 Yuan;
Crane month's rent is subject to market fluctuations in the economic impact of a great two years ago, demand outstrips supply, monthly rent depends on the seller's market, high during the peak of 7 Yuan / month. Crane is currently much lower monthly rent, with similar results here. Such as a monthly rental of 55,000 yuan terms, two years later, can recover the full investment (purchase of tower crane costs). Therefore, if there are follow-up of projects waiting to crane construction, or in the bases and logistics management, both have certain conditions, places purchased a tower crane as a fixed asset like Taiwan more cost-effective.
By comparing the analysis, such as determining purchased a tower crane Taiwan, then Taiwan would need to study what kind of a tower crane to buy the most cost-effective.
Cost analysis showed that of the tower crane, 50 m boom crane, costing more than about 40 m high crane tower crane costs about 10%. But the 50 m range of the effective operation of the crane tower crane than 40 m crane tower crane operating range of about 35% of large, using longer for the construction boom has brought more convenience and flexibility, expanded coverage of the tower crane.
Cost analysis also shows that of the tower crane, lifting capacity in the same circumstances (or the same model tower crane), rail-mounted tower crane tower crane construction costs than the fixed cost of much higher costs from the Crane purchase starting to save, we should buy a fixed tower crane. However, care must be fixed tower crane is divided into two kinds: one is fixed chassis, a base tower section is fixed. Choose a fixed tower crane tower base section most inexpensive, cost cheaper than rail-mounted crane 10% to 12.5%.
3. Tower crane-based approach to
Track-type tower crane-based customary practices as follows: first lay a solid foundation or make a layer of 3:7 dust pads, holes and gravel ballast, and then placed wooden sleepers, the rails laid on wooden sleepers. This practice timber consumed in large quantities, life is short, very unfit for heavy-duty crane. Today's recommended practices as follows: in consolidating the foundation of reinforced concrete floor on the set up or reinforced concrete sleeper beams, sleeper beams in the floor, or a fixed installation of I-beam with embedded parts, and then installed on the I-beam rail. To improve the efficiency of track-laying, laying the cost savings, and often the reinforced concrete sleeper beams, I-beam support care and the rail assembly together to form an assembly of 12.5 m long reinforced concrete rail foundation. The basis of this track is ideal for FO/23 B, HK40/21B, H3/36 B and other heavy use of self-elevating tower crane. Reposted elsewhere in the paper for free download http://eng.hi138.com
Chassis fixed crane from l to adopt reinforced concrete foundation block is most appropriate on the ground the foundation of a high endurance, such a desirable size of concrete foundation blocks for the 200 cm × 200 cm × 50 cm, top and bottom plates should be bi-directional reinforcement. Such as tower crane must be installed in the deep pit close by, it should be the basis of using bored pile caps to ensure the tower crane foundation of a solid and stable, and to take measures to prevent the pit slope landslides.
Fixed tower foundation for self-elevating tower crane must meet two requirements: First, the upper part of the tower crane foundation and the load evenly to pass no more than to endurance; 2 is to make the tower crane in a variety of adverse operating conditions are able to maintain overall stable without tipping. Thus, the tower crane foundation relatively large in size, basic weight of the tower crane should be equal to the weight of heavy pressure. This fixed tower crane tower crane base weight and a high degree of freedom is closely related to the greater weight of the free height of the higher basis. To FO/23 B tower crane, for example, when its free height of 59.8 m, the concrete foundation size required up to 6.5 m × 6.5 m × 1.7 m. If the tower crane required to set up in the basic construction phase in deep pit close by, worse off than the surface soil conditions, then this basis must also be supported by a bored pile. Therefore, in order to build the basis of the cost savings would be appropriate in mass concrete foundation of this block is decomposed into a number of pre-cast concrete horizontally and vertically, thereby constituting a prefabricated reinforced concrete foundation in order to achieve used repeatedly, so that decomposition of each project The tower crane on the basis of the project costs to a minimum.
4. With regard to ensuring safety in production
Summary at home and abroad with the experience of tower crane for building construction in order to ensure safety in production, we must effectively do the following.
(1) to conduct a second annual inspection each year, every 4 years to a time-depth and comprehensive inspection. Annual and annual transitions for each post-installation inspection by the local labor bureau on lifting transport equipment safety inspection department deployed to inspect. Four times a year-round in-depth inspection, except by the labor bureau sent outside, but also invited to design and installation of tower crane use of experienced engineers and technicians to participate. Annual inspection and a second four-year deal with a large tower crane inspections to make an authoritative assessment of the state of technology, and in greater detail that may be potential pitfalls so that timely and thoughtful overhaul the accident nipped in the bud.
Crane drivers must be at least 18 years of age through professional training and have some driving experience certificates of qualified personnel. Each tower crane tower cranes are available in a work log, the driver should carefully watch tower crane tower crane to complete overview of the work day, environmental conditions, crane operating characteristics of the various agencies, as well as carried out by maintenance.
Track crane drivers, the end of the working class away from the machine before the device shall clip rail clip firmly to prevent night-time wind Zhou Qi, tower cranes have been tipping winds scrapings orbit.
When more than one crane around a construction project, the adjacent two crane similar to the safe operation of the minimum distance between sites, China's general provisions of 5 m. Recent foreign provides crane between two adjacent minimum distance of 2 m, tower crane by lifting the bottom of the components from the highest point of the adjacent tower crane (tower top Division) is also the minimum clearance distance of 2 m. I believe that as long as the full attention and careful operation, according to this new foreign regulations.
According to our usual provisions of tower crane is not allowed l transport operator. However, the foreign proceeding from reality and make the new provisions: to meet certain conditions, the crane can be transported up the operations staff. Their specific conditions are as follows.
(1) The carriage of personnel baskets must have a spring at the bottom of a buffer device, there should be higher around the basket and closed the gate format retaining structure, safe and reliable slings and top security cover.
(2) The lifting of personnel baskets should be in the first two weeks in advance prior to use by the security inspection department full-time personnel security checks.
(3) The crane was being lifted during the first officers should also be made through the security check department full-time staff inspection.
Recent data from abroad has also introduced some requirements to meet the above conditions, the use of special platform attached with concrete hopper, concrete tower crane was being lifted, they will work with the transportation to pouring a concrete location, engaged in concrete pouring and vibrator (Figure 3), so that the template can be removed from along the Grand puts up for pouring concrete and installing the operating platform, both to simplify the construction, but also cost savings. This experience is worth noting and replication.