References...

1) Lee Yee Loon and Koh Heng Boon. Structure Repair and Rehabilition. (2010).

2) Professor Kamran M. Nemati. Shoring,Scaffolding and Underpinning. University of Washington Department Of Construction Management. (2007).

3) Professor Kamran M. Nemati. Excavations and Excavation supports. University of Washington Department Of Construction Management. (2007).

Why need to repair?

1. Durability problems due to poor or inappropriate construction material
2. Design or construction errors
3. Aggressive environments not properly understood or considered during the design stages
4. Increased loading requirements due to vast development of civilian and military vehicles
5. Increased life-span requirements made on ageing bridges
6. Exceptional or accidental loading

Example of temporary work...

building scoffolding

temporary support in meeting room

Type of temporary work...

     Shoring and scaffolding are the most frequent temporary structures in building construction. This lesson includes design, hardware, and installation of these systems. Underpinning is the installation of temporary or permanent support to an existing foundation to provide either additional depth or an increase in bearing capacity. (Kamran M.Nemati, 2007)

Shoring

     In multistory work, the shoring which supports freshly placed concrete is necessarily supported by lower floors which may not yet have attained their full strength, and which may not have been designed to carry loads as great as those imposed during construction. Construction loads may exceed design loads by an appreciable amount. Therefore shoring must be provided for enough floors to develop the needed capacity to support the imposed loads without excessive stress or deflection. Whether permanent shores or reshores are used at the several required lower floor levels depends on job plans.

      A portable jacking tool is used to make vertical adjustments. Metal shore jack fittings are available to fit over the end of 4×4 or 6×6 wood shore, thus transforming the piece of lumber into an adjustable shore, as shown in Figure 2. These devices are capable of varying the shore height as much as 12 inches.

Scaffolding

     Tubular steel form scaffolding was first designed to support loads imposed by the workers getting to the work area. Since the system of jacks in the tubular steel scaffolding makes it easy to adjust and level elevations, it is often used as a support for formwork. Since it is a modular assembly, it makes it an attractive option for rapid utilization for formwork support.

Underpinning

     Underpinning is the installation of temporary or permanent support to an existing foundation to provide either additional depth or an increase in bearing capacity. There are several existing conditions which may lead to the need for underpinning. They are :

-Construction of a new project with a deeper foundation adjacent to an existing building

- Settlement of an existing structure

- Change in use of a structure

- Addition of a basement below an existing structure

Formwork

     Formwork is the term given to either temporary or permanent moulds into which concrete or similar materials are poured. In the context of concrete construction, the falsework supports the shuttering moulds. (Wikipedia's , November 2010)

formwork of stair

What is temporary work in repair techniques?

     Repair may be defined as the modification of a structure damaged in its appearance (or serviceability), to restore, partly or wholly, the pre-existing characteristics of serviceability, load-bearing capacity, and if necessary, to improve its durability. The term "concrete repair" refers to any replacing, restoring, or renewing of concrete or concrete surfaces after initial placement. (Lee & Koh 2010)
    Temporary work are used to facilitate the construction of buildings, bridges, tunnels, and other above- and below-ground facilities by providing access, support, and protection for the facility under construction, as well as assuring the safety of the workers and the public. Temporary structures either are dismantled and removed when the permanent works become self-supporting or completed, or are incorporated into the finished work. Temporary structures are also used in inspection, repair, and maintenance work.