地盤老雜的生活 life of a Construction Worker

  Contents Note Contents Articles of Agreement Article 1 Article 2 Article 3 Article 4 Article 5 Article 6 Attestation The General Conditions 1        Interpretation and definitions 2        Contractor's obligations 3        Master programme 4        Architect's instructions 5        Documents forming the Contract and other documents 6        Statutory obligations 7        Setting out the Works 8        Materials, goods, workmanship and work 9        Intellectual property rights  10        Contractor's site management

Concrete Pump 石屎泵 If you need to pump concrete for your construction project, normally, you may have heard that you have two options: the boom pump and the line pump. A boom pump is a truck-mounted pump that is ideal for pouring large amounts of concrete quickly and pouring concrete at height. A line pump is a more compact stationary pump mounted to a trailer that is easier to maneuver around a job site and is ideal for horizontal pumping.  Concrete pumps are a convenient way to pump concrete, as they allow you to deliver the concrete exactly where you need it, rather than requiring you to try to continuously reposition a heavy cement mixer or haul concrete from the mixer to the delivery site. But how do you know when to use a line pump and when to use a boom pump? Here are the advantages and disadvantages of using a concrete boom pump vs. a line pump. Boom Pump Advantages First, it is important to understand what a concrete boom pump is,

- BASE CONFIGURATION Tower cranes are also characterised according to their mounting configuration. They are available as static bases, rail-mounted units and mobile units. a) Static bases -There are three main types of static bases. a1) In-situ base - The crane is mounted on special corner angles, frames or an expendable tower section, cast into the concrete foundation block. a2) On own base - The crane is mounted on its own base section or chassis which, without wheels and travelling gear, but with ballast, stands on a concrete base. a3) Climbing base - The crane is supported by the structure which it is being used to construct, and to which it is attached by climbing frames and wedges. The height of the cranes can be extended as the height of the structure increases by means of climbing supports attached to the frames. Climbing support can be metal ladders, rods or tubes. A climbing crane may be mounted initially on a fixed base and its support be later transferred to climbing frame

  - TOWER CONFIGURATION The towers can be further classified as being mono towers, inner and outer towers and telescopic towers. (a) Mono Towers - The jib is carried by a single tower structure which may be either fixed or slewing. Provision may be made in the design to permit the tower to be extended (b) Inner and Outer Towers - They are characterised by the jib being carried by a fixed or slewing inner tower which is supported at the top of the fixed outer tower. Provision may be made in the design to permit the outer tower to be extended (c) Telescopic Towers - The tower structure consists of two or more main sections which nest into each other to enable the height of the crane to be altered without the need for partial dismantling and re-erection. Telescopic towers are usually of slewing type and more common on rail-mounted and mobile tower cranes

  - JIB CONFIGURATION The main types of jib used on tower cranes are horizontal trolley jibs, luffing jibs, fixed-radius jibs, rear-pivoted luffing jibs and articulated jibs. a) Horizontal trolley jibs (“A” frame type) - They are held in a horizontal or slightly raised position by tie bars or ropes connected to an “A” frame on the top of the tower crane. The hook is suspended from a trolley which moves along the jib to alter the hook radius. A suitable allowance needs to be made for deflection when calculating the clearance between adjacent cranes b) Horizontal trolley jibs (flat top type) – They are connected directly to the tower top and do not require tie bars or ropes connected to an “A” frame. This reduces the overall height of the crane. The hook is suspended from a trolley which moves along the jib to alter the working radius. A suitable allowance needs to be made for deflection when calculating the clearance between adjacent cranes c) Luffing jibs - They are pivoted at the jib

安装塔式起重机 Installation of tower cranes from Allan Ha on Vimeo . Tower cranes are a modern form of balance crane that consist of the same basic parts. Fixed to the ground on a concrete slab (and sometimes attached to the sides of structures), tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. The base is then attached to the mast which gives the crane its height. Further, the mast is attached to the slewing unit (gear and motor) that allows the crane to rotate. On top of the slewing unit there are three main parts which are: the long horizontal jib (working arm), shorter counter-jib, and the operator's cab. Optimization of tower crane location in the construction sites has an important effect on material transportation costs of a project. Tower crane cabin Tower crane with "luffing" jib The long horizontal jib is the part of the crane that carries the load. The counter-jib carr