📺Complex Retaining Wall Design with MasterSeries [WEBINAR RECORDING]
Posted on January 25th, 2021 in Webinars
Summary
This webinar introduces MasterSeries software, a modular design tool for various structural elements, with a specific focus on complex concrete and masonry retaining walls. The presenter guides users through the software's capabilities, demonstrating how to design different wall types, including gravity, L-shaped, and stepped walls, while considering crucial factors like soil data, water tables, surcharges, and reinforcement. The demonstration highlights the software's flexibility in managing diverse loading conditions, multi-layered soils, and specific design challenges such as those presented by highway abutments or specialized hollow block systems, ultimately showcasing its ability to optimise designs and generate detailed outputs for construction.
Key Points
- Retaining Wall Design
- MasterSeries Software Features
- Design Considerations
- Masonry Wall Design
- Reinforcement and Detailing
Description
The "MasterSeries Software" offers a fully modular system for retaining wall design, allowing users to select only the necessary modules. The software supports the design of gravity retaining walls, which can be propped or tied, but it does not handle embedded walls or sheet piling.
Key aspects of retaining wall design using MasterSeries include:
• Design Standards and Soil Data: Designs are primarily based on Eurocode standards, though British Standards (BS) are also supported for certain aspects like highway loading. Users can define various soil properties, including subsoil density, base friction, submerged ratio, tension cracks, and cohesion. The software also allows for two layers of back soil with different properties, including inclination, and different materials for front, back, and base soils. It uses the Coulomb wedge theory for complex loading on soils and walls, rather than Rankine's theory.
• Design Checks and Issues: The software helps in addressing potential problems such as overturning, sliding, and bearing pressure. For instance, a lack of weight can lead to overturning or sliding problems, which can be mitigated by extending or thickening the base. Propping the base is another mechanical means to prevent sliding.
• Wall Configurations and Materials: MasterSeries can design various types of retaining walls:
â—¦ Simple walls with defined thickness and base dimensions.
â—¦ Traditional L-shaped walls, which can be efficient but may pose overturning and sliding issues if not designed correctly.
â—¦ Masonry walls, including plain, reinforced concrete, and composite cavity walls. For composite cavity walls, the outer leaf can be made thicker to act as the compression zone.
â—¦ Stepped walls, which are a common solution when a plain wall fails due to tension.
â—¦ Walls with piers for increased strength, especially in concrete block designs, though this is considered a less desirable solution for masonry due to reinforcement placement difficulties.
â—¦ Tapered walls, which provide greater strength at the base and taper upwards, frequently used in concrete designs.
â—¦ Gabion walls can be mimicked by designing a mass concrete blob with zero tensile strength for the upper section, relying on the concrete's density for stability.
â—¦ Steephock reinforced hollow block walls are a proprietary system that can be integrated into the software. These blocks are dry-fitted without mortar and are designed to allow for accurate placement of vertical and horizontal reinforcement, with concrete filling the voids.
• Loading Conditions: The software accommodates a wide range of loads, including surcharge (default 10 kN), water table effects, line loads (live/dead), partial surcharges, horizontal surcharges (e.g., from fences or railings), and wind loads. It also supports highway loading (HA, HB, construction) and bridge abutment loading categories, adhering to relevant standards.
• Reinforcement Design: Users can define and adjust reinforcement, including bar sizes (e.g., 8mm, 10mm, 12mm, 16mm, 20mm, 25mm), spacing (e.g., 133mm, 200mm), and cover. The software assumes reinforcement distribution is internal to maximise lever arms. Designs can be exported as DWG or DXF files for detailing, including U-bars, straights, open links, and bar schedules.
• Advanced Features and Considerations:
â—¦ The software can handle complex loading scenarios, such as loads on the wall and soil, and moments on the wall.
â—¦ It differentiates between designing "at rest" (where soil has moved slightly, common for highways) and "not at rest" conditions.
â—¦ The concept of nibs (projections) in wall design is discussed, with the code's current analysis suggesting they don't provide significant strength due to pressure propagation assumptions, making them less popular.
â—¦ For cavity walls and hollow block walls, slow pouring of concrete is crucial to prevent hydrostatic bursting.
â—¦ The MasterSeries client area provides sample files and technical notes for users, including standard set-ups for various wall types like Steephock walls.
Overall, MasterSeries provides a comprehensive and flexible tool for structural engineers to design various types of concrete and masonry retaining walls, considering a wide array of geometric, material, and loading parameters.