Corrugated Steel Structure (CSS), which was applied in North America in the early 1900s and has been installed in more than 1,000,000 places worldwide, has been in service since 1996, 100 years later, in Korea with POSCO, Korea Expressway Corporation, Seoul National University, Hanyang University, etc. It has been applied to the domestic market through commercialization research by specialized companies. Based on this, since the 2000s, it has been widely applied to road crossing passages, waterways and local small rivers, animal movement ecological passages, and Piam tunnels. Based on the advantages and economic feasibility of minimizing the existing vehicle traffic control during construction, it is a universal new construction method along with the existing reinforced concrete construction method. About 5000 corrugated steel plate structures have been installed and operated in Korea for 20 years.
However, regarding the various advantages of the construction method and the rapidly occurring demand, in the beginning, detailed explanations of the national design standards and specifications were insufficient. Problems such as deformation of the corrugated steel sheet occurred intermittently due to the lack of understanding of the backfill material and backfill compaction, which are the most important factors in
To improve this, ChungAmEnC has continuously improved and supplemented related standards through R&D with various related organizations, and based on domestic and foreign failure cases, provides optimized design solutions in advance for possible problems during actual construction. Optimized solutions include Virtual Construction: a three-dimensional system for step-by-step forecasting processes. (BIM LoD: 350 / Tekla, Trimble) and 3D Scanning (Leica P30 System, Cyclone ) Minimize errors that may occur at each construction stage I did. In addition, by providing 3D FEM, 3D printing and landscape design solutions, we will do our best to become a company that continuously develops and provides the world's best solutions that overcome the uncertainty of design and construction anxiety that customers have felt.
History of CSS
In 1896, an American civil engineer James. H. Watson and Starting with Stanley Simpson's patent, it was applied to small drainage channels in North America until the 1930s, and by the late 1900s, the maximum span was applied up to 11m and expanded to small bridges, passageways, and military facilities (ammunition depots). Since the 2000s, the span has been extended to 23m and applied to ecological tunnels, mine stockpiles, reclaim tunnels, and military facilities (hangars). 2014-2016 R&D and commercialization of extra-corrugated corrugated steel sheet (EXSCor) of Cheongam EnC With success, the maximum span was extended to 40m. It satisfies the maximum loads of CAT 797F (about 620 tons), EURO LM71, mine trucks, which could not be applied in the past with respect to live loading along with the expansion of span, so that it is economical, stable, and workable than concrete structures in multi-step processes. has enough competitiveness. In addition, extra corrugated steel sheet (EXSCor) is listed as a construction method and product according to design standards in Korea (KDS, KCS) as well as AASHTO LRFD and ASTM A796M in the United States.
ChungAmEnC
Construction construction order
One. Site preparation before assembly
1.1 Check the condition of sufficient curing of the foundation concrete.
1.2 Backfilling up to the height of the foundation is pre-worked to ensure worker and equipment safety.
1.3 Check the working space necessary for the temporary assembly of corrugated steel plates, and the stability of conduction according to the installation of crane equipment.
1.4 Check the arrangement of the base channel connected to the corrugated steel plate (refer to the supplier's installation drawing).
1.5 Remove foreign substances inside the Base Channel and check the cleanliness.
1.6 Inspect the corrugated steel sheet material brought into the site.
1.6.1 Material inspection items (comparison with final drawings and related standards)
1.6.2 Thickness inspection of corrugated steel sheet
1.6.3 Waveform width (Pitch) and valley depth (Depth) inspection
1.6.4 Inspection of effective length and effective width of corrugated steel sheet material
1.6.5 Inspection of steel plate plating status and coating amount (zinc) and *epoxy coating thickness (when design is applied)
1.6.6 Steel plate end and bolt hole finish inspection
1.6.7 Quantity check of corrugated steel sheet
2. Corrugated steel plate assembly
2.1 Corrugated steel plate assembly should be carried out according to 「Installation drawing」 or construction plan, and if necessary, support or rigidity
to maintain the design cross-sectional shape.
2.2 Each corrugated steel sheet brought into the site generally has different specifications and curvatures, so be sure to refer to the “installation drawing” when assembling.
Care must be taken not to change the order and position according to the
2.3 When stacking steel plates, gaps should be minimized, and 4 or more steel plates should not be stacked at the same time at one point.
No (except when a reinforcing plate is installed). Gaskets or packings should be used for steel plate connections.
2.4 Except where the radius of curvature changes, it is to be assembled so that the positions of joints are not continuous in the longitudinal direction of the structure.
< Example of installation drawing >
< BIM installation drawing example >
Appropriate waterproofing treatment for waterproofing shall be applied to the 2.5 bolt joint.
2.5.1 General waterproofing
“Urethane sealant” is applied to the overlapping parts of the steel plates, which have excellent impact resistance and elasticity, which is advantageous for structural behavior, and the bolt part is waterproofed with a “rubber cap injected with urethane sealant”.
2.5.2 Additional waterproofing
If the interior space is used for building purposes or when pedestrians are frequent in the downtown area, after general waterproofing, epoxy is applied to the overlapping part of the structure and the bolt part for additional waterproofing.
seam strength experiment
warpage test
haunch experiment
2.6. The nominal tightening torque of the bolts is 200N.m~400N.m, and the bolts should be assembled with an even torque throughout. After the steel plate assembly is completed, in the presence of the construction supervisor, for the longitudinal joint and the circumferential joint, the quantity corresponding to 3% of the total bolt quantity shall be randomly selected and inspected with a torque gauge. Bolts outside the nominal torque range If the quantity is more than 10% of the quantity to be inspected, all bolts should be tightened again.
3. Drainage treatment
3.1 Upper unpaved tunnel (open tunnel, ecological tunnel)
• In the upper part of the structure of the open tunnel and ecological tunnel, where there is usually no pavement layer, rainwater infiltration may create water pressure in the structure, so a separate drainage facility such as a perforated pipe should be installed.
• After installing a PE sheet on the upper part of the structure to block the penetration of rainwater, perforated pipes are installed at both ends to dispose of drainage through the inlet and outlet of the structure.
• As for the drainage plan for the connection part of corrugated steel plate and foundation concrete, a “leakage prevention foundation channel” that prevents seepage water from the base channel is installed to induce drainage to the lower part of the foundation concrete.
3.2 Upper pavement (trough/channel culvert, bridge)
• Aqueducts, canal culverts and bridges that cross the road below are drained from the upper pavement through a plume pipe.
• For the drainage plan between the corrugated steel plate and the base concrete, a “leakage prevention foundation channel” that prevents seepage water from the base channel is installed to induce drainage to the lower part of the base concrete.
4. Backfill and Fill
4.1 The backfilling and filling process of a corrugated steel plate structure is closely related to the stability and durability of the structure, and material selection and backfilling compaction are very important in the structural backfill range. *Refer to the structural backfill extent and compaction diagram specified in the drawing
4.1.1 Structural backfill material: The material for the part in direct contact with the corrugated steel plate structure (within 15mm)
4.1.2 General backfilling material: Other than structural backfilling materials, filling materials (within 80mm) and materials around the site can be applied according to the design.
4.2 For backfilling the structure, the layer thickness is marked every 20cm on the side of the assembled corrugated steel plate structure before material compaction so that the status of “layer compaction” can be identified.
4.3 Compaction of “the part where the lower curvature changes” of the closed section is very important, and sufficient compaction force must be secured. If compaction is difficult, use sand compaction and discarded concrete. Backfilling should be done up to “the part where the lower curvature changes”.
4.4 Backfill compaction of the side part is based on a large compactor. If it is partially difficult to use a large compactor, compaction must be managed using a mighty bag or a small rammer.
4.5 The thickness of the compaction layer after compaction is less than 20cm, and the compaction density must satisfy the requirements specified on the design drawings.
4.6 For backfilling of castles, cuts and connections, the slope of the pile or mower in contact with the backfill should be compacted by saw blade-type or stepwise tiering.
4.7 In case of compaction of structural backfill Within 60cm of the corrugated steel plate wall, heavy equipment, except for small compaction equipment, shall be controlled.
4.8 The difference in the compaction height of both sides of the structure should be less than or equal to the compaction thickness (20cm), and when the structure is deformed due to the flat earth pressure, immediately remove the flat earth pressure load and check the cross-sectional shape before performing the compaction again. *Refer to the 'displacement measurement' standard in Section 5
4.9 During side compaction, the compaction equipment should run parallel to the longitudinal direction of the structure and run at right angles to the longitudinal direction of the structure during upper compaction.
4.10 When backfilling the upper part, from the crown to the "minimum cover height" standard type: refer to design standards and design documents, rib type: over 1.5m, box type: over 0.3m, compaction must be made in the direction perpendicular to the structure with small equipment.
4.11 During upper compaction, vibration compaction is not performed up to the “minimum cover height”, the passage of heavy equipment except compaction equipment must be prohibited, and heavy objects must not be loaded.
5. Displacement measurement
5.1 For corrugated steel plate structures, the change in the shape and size of the section shall be measured immediately after assembly, during backfilling, and immediately after construction is completed.
5.2 After assembling, measure the cross-sectional size before starting backfilling, and if it deviates more than 5% from the design shape,
Loosen the bolts to match the shape and then reassemble.
5.3 When backfilling starts, the amount of deformation must be determined by measuring the cross-sectional size of the structure (measured at 3 or more different locations) immediately after each layer is compacted until the top cover construction is completed. If the amount of cross-sectional deformation exceeds the standard (refer to the table of allowable deformation amount below), construction should be stopped immediately, the cause should be identified, and appropriate measures should be taken to reduce the amount of deformation within the standard.
5.4 Displacement measurement management using corrugated steel plate displacement automation program (GTC-M®)
5.4.1 Through the corrugated steel sheet displacement automation analysis program, the cross-sectional shape is measured and managed step by step based on the initial shape of the cross section after assembling the structure, during backfilling up to “before the occurrence of negative moment” .
5.4.2 After 「Minimum Coverage」, until 「Planned Coverage」 or 「Upper Pavement」 is completed, the allowable range of the shape of the section and whether the displacement is convergence or not is measured and managed.
5.4.3 In case of changes in the surrounding environment such as heavy rain, check the displacement status by comparing it with the completed displacement management data.
5.4.4 Displacement measurement uses optical wave measuring equipment and laser range finder.
< Corrugated steel plate displacement automation program_GTC-M®>
5.5 Displacement measurement management using 3D laser scanner (Leica ScanStation P30, RTC360, dedicated program: Cyclone)
• It is used to identify local displacement along with displacement through point measurement for corrugated steel plate structures by construction stage (assembly, backfill, and completion).
• When applied to a structure that needs repair or reinforcement and a site where it is mixed with the surrounding complex devices, it is used to determine the cross section of the corrugated steel sheet by accurately identifying the interference with the existing structure. (Tunnel, culvert repair and reinforcement, vertical pit, transverse shaft, etc.)
• In case of long extension, large cross-section structures and curved sections, it is used to determine the shape of local displacement along with optical wave displacement measurement.
• It is applied to Post-Processing FEA which is converted into 3D modeling and used for future maintenance purposes.
Construction Procedure_Culvert Installation and Backfilling
Construction Procedure_Excavation tunnel installation and backfilling
*The corrugated steel plate assembly method may be changed according to the site conditions.
