Composite Shell System (CSS)

The CSS technology is a revolutionary new construction system utilizing internal spiral ribs to transfer shear force to/from the composite shell and make the concrete filled system provide ductility and confinement effects. 

Products

  1. •Composite Shell System (CSS)

  2. •RetroSheild

  3. •Blast Mitigation

  4. •Wind Turbine Tower

  5. •Electrical Poles

  6. •Sheet Piles

  7. •CS Pipes

Composite Shell System (CSS) offers the following advantages:


  1. •Stay-in-Place Form

  2. •Smaller Footprint

  3. •Easy Installation

  4. •Seismic Resistance

  5. •Blast Resistant

  6. •Corrosion Proof

  7. •Maintenance Free

  8. •Much Longer Life Cycle

The CSS technology may be applied for the following structural systems:


Bridge Girders and Bridge Piers

(King Stormwater Bridge, near Parm Springs, CA – built in 2002, Two Lane Highway)


The CSS has been considered by Caltrans in a demonstration bridge on California State Route 86 near the Salton Sea, the King Stormwater Channel Bridge, completed in 2002. The bridge consists of a 20.1 m (66 ft) two-span continuous beam-and-slab type bridge with a five column intermediate pier, see figures. Concrete filled CSS tubes comprise the longitudinal beams connected along their tops to a structural slab. The structural slab consists of an E-glass Fiber Reinforced Polymer (GFRP) deck system. The multi-column intermediate pier is composed of precast prestressed concrete piles, with the two outer piles encased by circular carbon/epoxy shells to evaluate environmental degradation.


References:

  1. •“Manufacturing and Construction Support Document for the Kings Stormwater Channel Bridge”, UCSD Report No. SSRP-99/05

  2. •“Preliminary Evaluation of the Hybrid Tube Bridge System”, UCSD Report No. TR-2000/4.

  3. •http://hpwren.ucsd.edu/news/021115.html

Bridge Pylons and Bridge Girders

(I-5 Bridge, San Diego, CA – Designed and Tested for Performance, Two Lane Traffic and Two Lane Bike/Pedestrian Trail)


The I-5/Gilman Advanced Technology Bridge is a 137 m (450 ft) long cable-stayed bridge supported by a 59 m (193 ft) high A-frame pylon, utilizing concrete filled CSS tubes. The bridge system is a dual plane, asymmetric cable-stayed design as shown in Figures 1 to 3. The superstructure has an overall width of 18.3 m (60 ft) and a structural depth of approximately 1.3 m (4.25 ft). The bridge accommodates two traffic lanes 3.7 m (12 ft), two bicycle lanes 2.4 m (8 ft), two 1.5 m (5 ft) pedestrian walkways, and utility service ducts located between barrier rails near the stays.


The structural design concept of the bridge consists of a FRP panel stiffened steel free deck system and is supported on and composite with transverse CSS cross-beams. These crossbeams are spaced 2.4 m (8 ft) on center and supported on the longitudinal CSS edge-girders. The CSS edge girders are concrete filled and held up at 4.9 m (16 ft) intervals by the cable stays.


The CSS pylon is approximately 59 m (193 ft) tall and the pylon legs at the base span a distance of 35.8 m (117 ft). The CSS pylon leg is composed of 9.8 m (32 ft) sections that are spliced together with conventional steel reinforcement.



References:

  1. •“Seismic Performance of the Pylon Connection for the I-5/Gilman Advanced Technology Bridge”, UCSD  Report No. DDRP-2001/20

342-mm ID, 10-mm thick CSS

Piles for Bridge, Building and Roadway

(Inchon Bridge, Analyzed for Comparison)

1.5m Dia, 9mm thick CSS for Pylon


CSS Pylon Test at UCSD


P-M Diagrams and Moment Curvature Curves for Design Comparison (RC Design and CSS Design Options)


The FRP design is a strength-based design which is reflected by the P-M curve of the original RC pile at the critical section, i.e., the composite pile is designed such that the P-M strength envelope equals or exceeds that of the original RC pile. In addition to strength, the composite pile is designed such that the area under the moment-curvature curve at the critical section equals or exceeds that of the original RC pile. This assures equal energy absorption capacitates for both the original and the composite designs. The new pile design consists of composite shell system (CSS). This system incorporates a carbon fiber-reinforced polymer (CFRP) or a hybrid CFRP-GFRP tube with interior ribs which is filled with concrete. (Here GFRP refers to glass fiber-reinforced polymer.) This alternate CSS pile design eliminates the need for a steel casing, the hoop steel and a majority of the longitudinal steel. The CSS pile design also offers a possible reduction of the drilled shaft diameter of approximately 15%.


Saving for this type of application will be significant (30%-50% compare to the conventional RC construction with steel casing) with all the added benefit such as non-corrosive, ductile, blast resistance, seismic resistance, maintenance free and longer life cycle.



Reference:

  1. •“Preliminary design of a composite pile as an alternative to the SAMSUNG RC drilled pile”, CSI Report.

Conventional RC Design

(Steel Casing, Double Re-bar Cage)

CSS Design

(No Steel Casing, No Rebar Cage)