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Problem
Problem
Masonry walls constructed without structural reinforcement can fall under lateral loads associated with heavy winds or seismic forces. Most of the 225,000 deaths from the 2010 earthquake in Haiti were from unreinforced buildings that collapsed. Structural reinforcement of walls required by code in some areas relies on placing steel rebar in hollow core wall units that are connected to a footing and subsequently filled with grout.
Masonry walls constructed without structural reinforcement can fall under lateral loads associated with heavy winds or seismic forces. Most of the 225,000 deaths from the 2010 earthquake in Haiti were from unreinforced buildings that collapsed. Structural reinforcement of walls required by code in some areas relies on placing steel rebar in hollow core wall units that are connected to a footing and subsequently filled with grout.
However, there are dangers working with rebar and it costs up to 20 percent more to construct earthquake and wind-resistant buildings. A common practice is to extend rebar upward from footings and for masons to lift heavy blocks up and over the rebar, sometimes at heights of 15 feet. Considerable time is required to lift the blocks over the rebar, breakage of blocks is common, and it is difficult to keep mortar on the block edges during the repetitive lifting process.
However, there are dangers working with rebar and it costs up to 20 percent more to construct earthquake and wind-resistant buildings. A common practice is to extend rebar upward from footings and for masons to lift heavy blocks up and over the rebar, sometimes at heights of 15 feet. Considerable time is required to lift the blocks over the rebar, breakage of blocks is common, and it is difficult to keep mortar on the block edges during the repetitive lifting process.
Rebar is conventionally used to reinforce concrete masonry walls and footing, however:
Rebar is conventionally used to reinforce concrete masonry walls and footing, however:
- Injuries occur installing
- Improper installations
- Blocks break
- Poor mortar joints
- Difficult to inspect
- Requires time and skill
Difficulty Tying Rebar Inside a CMU Core
Difficulty Tying Rebar Inside a CMU Core
Workers often neglect using protective caps on exposed rebar or use improper caps. Serious injuries have resulted from workers falling on rebar in addition to death by impalement. Other serious accidents occur while working with rebar, such as cutting or bending the rebar.
Workers often neglect using protective caps on exposed rebar or use improper caps. Serious injuries have resulted from workers falling on rebar in addition to death by impalement. Other serious accidents occur while working with rebar, such as cutting or bending the rebar.
Cutting rebar can be dangerous and typically requires the use of a torch, portable rebar cutter, hydraulic bolt cutter, reciprocating saw, or grinder.
Cutting rebar can be dangerous and typically requires the use of a torch, portable rebar cutter, hydraulic bolt cutter, reciprocating saw, or grinder.
Wire rope is significantly easier to cut with a manual bolt cutter or a grinder. In addition, it may not be necessary to cut the upper sections of wire rope extending from the top of a masonry wall as excess wire rope can simply be placed into adjacent hollow cores.
Wire rope is significantly easier to cut with a manual bolt cutter or a grinder. In addition, it may not be necessary to cut the upper sections of wire rope extending from the top of a masonry wall as excess wire rope can simply be placed into adjacent hollow cores.
Conventional Approach
Conventional Approach
Rebar Animation.mp4
Time Consuming Tying Rebar in a Complex Footing
Time Consuming Tying Rebar in a Complex Footing
Maintaining Proper Rebar Spacing for CMU Alignment
Maintaining Proper Rebar Spacing for CMU Alignment
Bending Rebar in a Small Core of a Hardscape Masonry Unit
Bending Rebar in a Small Core of a Hardscape Masonry Unit
Difficulty Laying Heavy CMUs in a Deep Footing while Keeping Rebar Properly Capped
Difficulty Laying Heavy CMUs in a Deep Footing while Keeping Rebar Properly Capped
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