Cost-Benefit of S690Q hot rolled steel plate in Bridge Weight Reduction

In bridge engineering, material lightweighting directly affects bridge span design, construction difficulty, and life-cycle cost. S690Q hot rolled steel plate has become the core material for bridge weight reduction due to its advantage of high specific strength (strength/density) - compared with ordinary carbon steel plate, under the same load-bearing capacity, S690Q hot rolled steel plate can achieve a weight reduction effect of 30%, and significantly reduce the comprehensive cost.

case

The approach bridge section of a cross-river bridge project was originally designed to use Q345B hot rolled steel plate (yield strength 345MPa), with a web plate thickness of 32mm and a flange plate thickness of 40mm; later, it was replaced with S690Q hot rolled steel plate, the web plate thickness was adjusted to 22mm, and the flange plate thickness to 28mm, while keeping the section bending modulus unchanged. The weight, construction cost, and operation and maintenance cost of the two schemes were compared.

Weight Reduction Effect and Direct Cost Savings

Material Weight: For a single 12-meter-long bridge box girder, the weight of the Q345B scheme is 18.6 tonnes, and the weight of the S690Q hot rolled steel plate scheme is 13.0 tonnes, with a weight reduction of 5.6 tonnes and a weight reduction rate of 30.1%. Calculated by the steel procurement price (Q345B is about CNY 4,500 per tonne, S690Q is about CNY 6,800 per tonne), the material cost of a single box girder is: CNY 83,700 for the Q345B scheme and CNY 88,400 for the S690Q scheme, an increase of only CNY 4,700.

Transportation and Hoisting Cost: After weight reduction, the transportation vehicle for a single box girder was changed from a heavy-duty trailer (load capacity 20 tonnes) to an ordinary trailer (load capacity 15 tonnes), and the transportation cost was reduced from CNY 1,200 per section to CNY 800 per section; the hoisting equipment was changed from a 500-tonne crane to a 300-tonne crane, and the hoisting cost was reduced from CNY 8,000 per section to CNY 5,000 per section. The total transportation + hoisting cost for a single box girder was saved by CNY 3,400, offsetting the increase in material cost, resulting in a net saving of CNY 2,930 per section.

• Price Of S690Q Steel Plate

EN10025-6 S690Q, DIN EStE690V High yield strength structural
US $900.0-1100.0 / Ton ( FOB Price)

high strength grade S690Q1 steel plates for spare parts
US $820.0 / Tons

flat steel quenched and tempered of high strength steel 1.8988 S690Q
US $500-1200 / Metric Ton

high strength low alloy steel plate S690Q
US $475-690 / Metric Ton

S690Q S690QL S690Q High Tensile Structural Steel PLate
US $550-800 / Ton ( FOB Price)

Long-term Operation and Maintenance Cost Advantages

Anti-corrosion Cost: S690Q hot rolled steel plate has higher surface flatness, and can be directly subjected to shot blasting derusting + anticorrosive coating after hot rolling, with paint film adhesion ≥5MPa; while Q345B hot rolled steel plate requires additional leveling treatment, with paint film adhesion of about 3.5MPa. Calculated based on the 20-year operation and maintenance cycle of the bridge, the number of anticorrosive coating renovations for the S690Q scheme was reduced from 3 times to 2 times, saving about CNY 12,000 in anti-corrosion cost for a single box girder.

Structural Maintenance Cost: S690Q hot rolled steel plate has excellent fatigue performance (fatigue strength ≥300MPa), while the fatigue strength of Q345B is about 200MPa; measured data show that the fatigue life of the S690Q box girder can reach 2 million load cycles, while that of Q345B is only 800,000 cycles. Within 20 years, the S690Q scheme does not require structural reinforcement, while the Q345B scheme needs reinforcement at the 10th year, with a reinforcement cost of about CNY 50,000 per section.

Engineering Performance Assurance

S690Q hot rolled steel plate adopts the Thermo-Mechanical Control Process (TMCP), with a grain size as fine as grade 7-8, which not only has high strength but also good plasticity (elongation ≥15%) and toughness (impact energy at -20℃ ≥47J). In the bridge load test, the maximum deflection of the S690Q box girder was 12mm, far lower than the design limit of 18mm; while the maximum deflection of the Q345B box girder was 15mm, close to the limit. In addition, the weldability of S690Q hot rolled steel plate is compatible with the submerged arc welding process commonly used in bridges, and the strength of the welded joint after welding is ≥650MPa, without defects such as cracks and porosity.

EN 10025-2 S690Q Sheet and Plates EQUIVALENT GRADE

In summary, although the per-tonne procurement price of S690Q hot rolled steel plate is higher, the savings in transportation, hoisting, and operation and maintenance costs brought by weight reduction result in a cost saving of more than CNY 60,000 for a single box girder over its life cycle. Moreover, it can improve the structural safety and service life of the bridge, making it one of the optimal choices for the design of long-span, lightweight bridges.

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FAQ

What is the difference between S690Q and S690QL?

S690Q: Minimum impact toughness tested at -20°C (30J average). → Typical Use: Cranes in temperate climates, quarry equipment. S690QL: Certified for -40°C and below (≥40J impact toughness). → Critical Use: Arctic pipelines, offshore platforms, mining vehicles in Siberia.

What grade is S690QL material?

S690QL is a high strength quenched and tempered steel grade that complies to steel specification EN 10025. The designation S690QL refers to a minimum yield strength of 690 MPa.

What is S690 grade steel?

S690 high yield & fine grain steel plate is a high strength, quenched and tempered fine-grain structural steel. Structural steel S690 is used in structures that must withstand very heavy loads. This grade is meant for structures where weight savings is important.

What is the equivalent of S690 steel?

Approximate equivalents
ASTM A514, EN 10149-2 Grade S700MC, AS/NZS 3579 Grade 700, AM 700, Bisalloy 80.

What is the price of S690QL material?

S690QL High Strength Steel Plates, Thickness: 5mm to 150mm at ₹ 135/kilogram in Mumbai.

What is the hardness of S690 QL steel?

S690QL steel stockholders and suppliers. S690QL is a quenched and tempered high strength steel supplied in full plates or cut pieces with delivery to the whole of the UK. With its high yield of minimum 690MPa it offers better strength than standard carbon steel grades.

What is the effective use of high strength S690 steel in construction?

The high strength S690 steels have an excellent strength-to-self-weight ratio, and they are highly efficient to be used in heavily loaded structures. Typical applications include piles and columns in buildings and supporting members in bridges.

What is the difference between S890QL and S690QL?

S690QL, S890QL, and S960QL are all water quenched and tempered steels that comply with the EN10025:6:2004 specification. These ultra high strength steels have a minimum yield strength of 690 MPa, 890 MPa, and 960 Mpa respectively, making them ideal for use in the haulage sector.

What is the difference between S700MC and S690ql?

The S700MC Steel is basically a structural steel plate developed especially for applications requiring high yield strength. They are used for several load bearing applications. The S690ql is a low alloy structural steel which is high in strength and comes with good weldability.

What is the yield strength of s690 steel?

690 MPa.

Yield strength of 690 MPa. Used in structures bearing extremely heavy loads, such as bridges, offshore drilling rigs and buildings, as well as in heavy construction equipment and cranes.