What is the proper vinyl sheet pile driving method for different soil types?

“Pitch and drive” method is the most practical way of pile driving in loose soils especially when using short piles. Also called “set and drive”, this method installs piles one by one. However, with only one interlock in control, sheet piles have high tendencies of rotating from the axis and leaning forward or backward. Panel driving is recommended for the dense deposit of sands and compact cohesive soils such as heavy clay or in presence of obstructions. In this method, a number of piles are interlocked together before driving. The panel of piles is supported by guide frames and driven gradually in sequence, sometimes in a staggered manner. The method can achieve installations of longer piles in more difficult ground conditions with better results in sheet pile alignment and verticality. In cases of difficult ground conditions such as hard strata and the presence of obstructions, driving assistance is employed along with a proper selection of driving method and equipment. Jetting and drilling help by loosening or eliminating obstructions by creating pressure right under the tip of the sheet pile being driven. Long and slender PVC sheet piles require steel mandrels as supports when driven in such conditions. Mandrel, which shape is similar to sheet pile profiles, increases the rigidity of Plastic Sheet Pile and supports the weight of the driving equipment such as a vibro-hammer.

What is the proper machine to drive piles in different conditions?

Impact driving is suitable for all soil types but appears to create the highest degree of stress to sheet piles. It is more appropriate to cohesive soils and soft soils such as silts and peats, loose medium to coarse sand, and gravels free of rock inclusions. Drop hammers such as the hydraulic hammer are the common types of impact-driving machinery. Driving using vibratory hammers is ideal for non-cohesive or granular soils such as soft soils and round-grained sand or gravel. It has also shown satisfactory performance in sandy, silty, or softer clay soils. It is less effective in angular-grained materials and soils with a firm consistency. With the introduction of vibration, however, the sub-soil can be further compacted, increasing penetration resistance and ultimately-refusal. If this is the case, driving aids like jetting and drilling might be necessary.

What are the pvc sheet pile selection criteria for soil condition of different hardness?

General rule of the thumb: “the harder the soil, the stronger and stiffer sheet pile section should be used”. Driveability of a pile section is a consequence of its cross-sectional properties (thickness, depth, and width), designed shape, length, grade, and the applied load. Hardness of soil strata characterized by SPT or CPT values is used to predict soil resistance which is essential in the calculation of driving force to be applied. Knowing the range of force from the selected driving machine, corresponding sheet pile sections can be picked according to their yield strength and elastic modulus.

How should I choose a sheet pile section for soils with, say, SPT Value, N=30? Can I still consider using vinyl or shift to steel?

Every sheet pile material has a design purpose, strengths, and areas of improvement. The availability of different materials denotes the need for a special material for a specific application. Plastic or synthetic sheet piles for example are known for being light and corrosion-resistant; Steel sheet piles are recognized for their extraordinary strength and versatility; and so on.

Nov 6, 20214 min read

Steel-Concrete Composite Construction

Name: ESC Group (Middle East)
Address: Industrial Area City of Abu Dhabi, Abu Dhabi, 131355, AE
Telephone: +971 2550 6188
Price range: AED

Principle

Construction materials of different properties are combined to interact and respond against loads in synchronization rather than individually. These composite materials are physically connected to utilize their distinct strengths and features to form a single unit stronger than any separate parts.

Composite construction is meant to achieve efficient and lightweight structural solutions for construction and other related industries.

Background

steel fabrication — Photo Credits: sciencedirect.com

This engineering and construction method has been widely practiced over a century ago, more dominantly involving the steel-concrete connection. Concrete-encased steel sections were initially developed as composites with the purpose of overcoming the effects of fire while ensuring stability against axial and bending forces.

Composite columns with reinforced concrete core and steel pipe or steel tubular shell were introduced to provide an integral and permanent formwork. Profiled galvanized metal sheets were also introduced to eliminate traditional formworks and at the same time, increasing the strength of reinforced concrete slabs.

Standards

Design of composite beams and composite slabs for buildings are covered by BS EN 1994-1-1
Design of Composite Steel and Concrete Structures are covered by BS EN 1990-1999 Eurocode 4
Australian Bridge Design Code, Section 6: Steel and composite construction
BS 5400 British Standard code of practice for the design and construction of steel, concrete and composite bridges
ASHTO: Standard Specifications for Highway Bridges; 24 CFR 200 Sub-part S
Concrete Slab Stresses in Partial Composite Beams and Girders, American Institute of Steel Construction, Vol. 21

Applications

Composite construction is extensively used in bridges, multistorey buildings, warehouses, marine structures, and more. Many applications in the mentioned structures are categorized as beams & girders, floor systems, and column systems.

Composite Beams and Girders. Composite beam includes a steel section in I or W shape attached to a concrete slab by shear connectors atop of it. They have been recognized as one of the most economical structural systems for both multistorey buildings and bridges.

Obviously, building and bridge floors should be stiff and massive enough to reduce deflection and vibrations. In this case, reinforced concrete is undoubtedly the material of choice. The supporting beam or girder, however should have a superior strength-weight ratio, a quality that only steel can offer.

Composite Floor Systems. Composite floor system consists of steel beams, profiled metal decking, and reinforced concrete slab. These materials are combined in a compact and very efficient way to form a profile that is basically designed to hold gravity or dead loads as well as traffic loads.

Composite floor systems are mostly used as bridge decks and floor slab for wide range of building classifications largely for elevated car parks and multistorey commercial buildings.

Composite Column Systems. Composite columns can either be concrete-filled steel tube or concrete-encased steel element. Either way, composite columns are advantageous as follows.

Flexural resistance of steel pipe or tube is maximized when provided with concrete infill
Steel casing prevents spalling and confines the concrete.
Concrete infill delays local buckling of the steel casing and enhances compression resistance
Steel casement replaces formwork and reinforcing steel.

Advantages

The success and versatility of composite construction can be stated in a simple and straight forward explanation - concrete responds excellently in compression and steel behaves the same in tension.

Joining the two materials together as a structure, these strengths can be used to achieve a highly efficient and lightweight design that can effectively resist both axial and flexural forces. Other benefits and advantages are as follows:

Composite systems are over 25% lighter than concrete construction. As a result, site erection and installation are easier, and labor costs can be minimized.
Steel-concrete composite can have high strength from a relatively small cross-sectional area.
The reduced weight of composite itself reduces the forces in those elements supporting them. In this way, supporting members including foundation costs can also be reduced.
Superior strength-to-weight ratio of composite materials allows compact designs which are expected to be aesthetical, economical, safe, and green.
Composite systems eliminate the costly activities of traditional concrete forming like propping, stripping, and other temporary works.
Steel and concrete can be arranged to produce an ideal combination of strength according to calculated requirements.
Concrete-encased steel elements has good resistance to buckling, fire, and corrosion.
Composite beams can cover longer spans without the need of intermediate columns, thanks to steel.
Composite columns reduce the requirement of lateral reinforcement and time-consuming fixing of lateral ties, as well as providing easier connection to steel beams of a steel-framed structure.
Composite columns involving steel tube or pipe casing simplifies foundation works and construction in bodies of water.
In marine construction, pouring of concrete under water is made possible by applying composites. Driven steel pipes and sheet piles serves as integral and permanent formworks for concrete infill.
Concreting of succeeding floors may proceed without having to wait for the previously cast floors to gain strength. The steel decking system provides positive moment reinforcement for the composite floor, requiring only small amounts of temperature bars to control cracking.

Summary

The benefits of combined steel-concrete construction are characterized by three major aspects: speed, performance, and value.

Steel-concrete composite is about 30% lighter than reinforced concrete and slightly heavier than structural steel by 2%. This significant reduction in weight of composite materials compared to reinforced concrete along with the elimination of huge amount of false works contributes to a huge factor in reducing construction timelines.
With concrete being strong in compression and steel in tension, the combination of the two materials has proven and excellent results in enhancing the structural performance of the product composite unit. Application of steel-concrete composite can increase the maximum shear strength of a floor slab by 85% according to the results of a study by ASCE.
Overall savings using steel-concrete composite can be as high as 10% compared to reinforced concrete and 7% when compared to structural steel. Steel encased with concrete does not only improve the strength of the composite members but protect the entire structure from adverse effects of fire, calamities, and corrosion.

Why Consult ESC?

ESC Steel Structures is one of the top providers of structural steel fabrications around the world.

ESC’s capabilities include Steel Bridge Structures, Bailey Bridge, Pre-Engineered Steel Buildings / Pre-Fabricated Steel Buildings, Offshore Steel Structures, Mining and Excavation Structures, Pressure Vessel Fabrication, Steel Towers, Rail Infrastructures, Material Handling Structures, and more.