THE MAIN TYPES OF SCAFFOLDING IN BUILDING CONSTRUCTION

THE MAIN TYPES OF SCAFFOLDING IN BUILDING CONSTRUCTION

 

SCAFFOLDING

Scaffolding is a temporary rigid structure made of still, bamboo or timber. The primary aim of constructing a scaffold is to create a platform on which mason can work at different heights. Scaffolds also help to lift materials for the immediate uses at different heights

USEFUL TERMS RELATED TO SCAFFOLDING:

1. Standard: It is a vertical member supported on the ground.

2. Ledgers: Ledgers are the longitudinal horizontal members connected with standards.

3. Braces: Braces are the diagonal members that are connected with standards to stiffen the structure.

4. Put Logs: Put logs are the transverse horizontal members that are 90 cm in length and are generally spaced 120 cm apart. They are provided to support the working platform.

5. Transoms: When both the ends of put logs are connected with ledgers, it is called transoms.

6. Boarding: Boarding is a horizontal member supported by put logs. It is used to enable the mason and materials.

7. Guard Rail: It is similar to ledgers, used for a better protection at the working level.

8. Toe Board: It is a long horizontal board of wood used at the different working level.

TYPES OF SCAFFOLDING:

Different types of scaffolding are described below:

1. Brick layer’s scaffolding,

2. Mason’s scaffolding,

3. Steel or tubular scaffolding,

4. Needle scaffolding.

1. BRICK LAYER’S SCAFFOLDING:

This type of scaffolding consists of standards firmly secured in the grounds at 2.4 to 3 m. The standards are connected to each other by ledgers at every rise of 120 to 150 cm. They are provided on the building side of the standards and are secured in position by rope-lashing. Putlogs are lashed on the ledgers at one end and into the holes in the wall at the other end. In high scaffolding, cross braces are invariably used to stiffen the temporary structure. Braces consist of poles tied by rope-lashing on the standards.

2. MASON’S SCAFFOLDING:

Since it is difficult to leave holes in the stone masonry to provide a bearing for the putlogs, in mason’s scaffolding two frames of standards, at a distance of 1.5 m from the first one. Thus the mason’s scaffolding is entirely independent of the stone wall.

Close mason’s scaffolding: They are supposed to carry loads of heavy blocks of stones and the stresses produced on account of the lifting device and hence they are made stronger by placing the standards at a fairly close distance apart.

3. STEEL OR TUBULAR SCAFFOLDING:

The method of construction of steel scaffolding is similar to that of brick layer’s and mason’s scaffolding. The primary differences are

  • Instead of using timber, steel tube of diameter of 40 m to 60 mm are used
  • Instead of using rope lashing, special types of steel couples are used for fastening
  • Instead of fixing the standards into the ground, it is placed on base plate

The gap between two standards in a row is generally kept within 2.5 m to 3 m. These standards are fixed on a square or round steel plate (known as Base Plate) by means of welding.

Ledgers are spaced at every rise of 1.8 m. Length of the putlogs are normally 1.2 m to 1.8m.

Advantages of the Steel Scaffolds are as follow:

  • It can be erected or dismantled more rapidly in comparison to timber scaffolding. This helps in saving construction time.
  • It is more durable than timber. Therefore it is economical in long run.
  • It has more fire resisting capacity
  • It is more suitable and safe to work at any height.

4. NEEDLE SCAFFOLDING:

When scaffolding is to provide for a building on the side of a busy street where the construction of ordinary scaffolding will obstruct the traffic on road, needle scaffold is used. The scaffold is erected from window corners of string courses by means of projecting needles. A needle is a timber beam which cantilevers out through the holes cut in the wall. From inside the needles are supported on sole pieces and are prevented from lifting up by vertical struts wedged between the needles and the headpieces. The projected end of the needle is supported by an inclined strut which rests on the window sill. The joint between the raking or inclined strut and the needle is clamped by mean of dogs. The arrangement provides the staging for the erection of ordinary type of scaffolding.

 

 

How LiDAR is Being Used to Help With Natural Disaster Mapping and Management

How LiDAR is Being Used to Help With Natural Disaster Mapping and Management

 

Michael Shillenn, vice president and program manager with Quantum Spatial outlines three projects where LiDAR data from the USGS 3D Elevation Program (3DEP) has been used to assist in planning, disaster response and recovery, and emergency preparedness.  

This month the United States Geological Survey (USGS) kicks off the fourth year of its grant process that supports collection high-resolution topographic data using LiDAR under its 3D Elevation Program (3DEP). The 3DEP program stemmed from the growing national need for standards-based 3D representations of natural and constructed above-ground features, and provides valuable data and insights to federal and state agencies, as well as municipalities and other organizations across the U.S. and its territories.

With geospatial data collected through 3DEP, these agencies and organizations can mitigate flood risk, manage infrastructure and construction projects, conserve national resources, mitigate hazards and ensure they are prepared for natural and manmade disasters.

Here’s a look at three projects undertaken by Quantum Spatial Inc. on behalf of various government agencies, explaining how the LiDAR data collected has been used to support hurricane recovery and rebuilding efforts, provide risk assessments for potential flooding and address potential volcanic hazards.

Hurricane Sandy Disaster Response and Recovery

Hurricane Sandy was one of the deadliest and most destructive hurricanes of the 2012 Atlantic hurricane season, impacting 24 states, including the entire Eastern seaboard from Florida to Maine. The Disaster Relief Appropriations Act of 2013 enabled the USGS and National Oceanic and Atmospheric Administration (NOAA) to support response, recovery and mitigation of damages caused by Hurricane Sandy.

As a result, USGS and NOAA coordinated the collection of high-resolution topographic and bathymetric elevation data using LiDAR technology along the eastern seaboard from South Carolina to Rhode Island covering coastal and inland areas impacted by the storm. This integrated data is supporting scientific studies related to:

  • Hurricane recovery and rebuilding activities;
  • Vulnerability assessments of shorelines to coastal change hazards, such as severe storms, sea-level rise, and shoreline erosion and retreat;
  • Validation of storm-surge inundation predictions over urban areas;
  • Watershed planning and resource management; and
  • Ecological assessments.

The elevation data collected during this project has been included in the 3DEP repository, as well as NOAA’s Digital Coast — a centralized, user-friendly and cost-effective information repository developed by the NOAA Office for Coastal Management for the coastal managers, planners, decision-makers, and technical users who are charged to manage the nation’s coastal and ocean resources to sustain vibrant coastal communities and economies.

In this image, you’ll see a 3D LiDAR surface model colored by elevation centered on the inlet between Bear and Browns Island, part of North Carolina’s barrier islands south of Emerald Isle in Onslow Bay. The Back Bay marshlands and Intercostal Waterway also are clearly defined in this data.

3D LiDAR surface model colored by elevation centered on the inlet between Bear and Browns Island, part of North Carolina’s barrier islands south of Emerald Isle in Onslow Bay.

Flood Mapping and Border Security along the Rio Grande River

Not only is flooding one of the most common and costly disasters, flood risk also can change over time as a result of development, weather patterns and other factors. The Federal Emergency Management Agency (FEMA) works with federal, state, tribal and local partners across the nation to identify and reduce flood risk through the Risk Mapping, Assessment and Planning (Risk MAP) program. Risk MAP leverages 3DEP elevation data to create high-quality flood maps and models. The program also provides information and tools that help authorities better assess potential risk from flooding and supports planning and outreach to communities in order to help them take action to reduce (or mitigate) flood risk.

This image depicts a 3D LiDAR surface model, colored by elevation, for a portion of the City of El Paso, Texas. U.S. and Mexico territory, separated by the Rio Grande River, is shown. Centered in the picture is the Cordova Point of Entry Bridge crossing the Rio Grande. The US Customs and Border Protection, El Paso Port of Entry Station is prominently shown on the north side of the bridge. Not only does this data show the neighborhoods and businesses that could be impacted by flooding, but also it provides up-to-date geospatial data that may be valuable to border security initiatives.

3D LiDAR surface model, colored by elevation, for a portion of the City of El Paso, Texas. U.S. and Mexico territory, separated by the Rio Grande River

Disaster Preparedness Around the Glacier Peak Volcano

The USGS has a Volcano Hazards Program designed to advance the scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity. This program monitors active and potentially active volcanoes, assesses their hazards, responds to volcanic crises and conducts research on how volcanoes work.

Through 3DEP, USGS acquired LiDAR of Glacier Peak, the most remote, and one of the most active volcanoes, in the state of Washington. The terrain information provided by LiDAR enables scientists to get accurate view of the land, even in remote, heavily forested areas. This data helps researchers examine past eruptions, prepare for future volcanic activity and determine the best locations for installing real-time monitoring systems. The LiDAR data also is used in the design of a real-time monitoring network at Glacier Peak in preparation for installation in subsequent years, at which time the USGS will be able to better monitor activity and forecast eruptions.

This image offers a view looking southeast at Glacier and Kennedy Peaks and was created from the gridded LiDAR surface, colored by elevation.

3D LiDAR surface model of a view looking southeast at Glacier and Kennedy Peaks.

 

Source : www.gislounge.com

Concrete Pavement Design Spreadsheet

Concrete Pavement Design Spreadsheet

 

Pavement Design ( Wheel Loading ) – Using CCAA Approach

A concrete pavement is to be designed to support loading from mining trucks with an axle load of 640 kN with a wheel spacing of 4.97 m. All areas of the pavement may be traversed by the mining truck. The pavement design shall be designed for an operating life of 20 years, and it has been estimated that an average of 25 daily load repetitions may occur.

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