ES600 Technical Study Summary – United Arab Emirates University

Use of ES600 Intermediate High-Strength Steel Rebars in Concrete Structures Based on ACI 318-19 Building Code

The United Arab Emirates University (UAEU) have provided a full study of the potential use of ES600 intermediate high-strength steel reinforcing bars in reinforced concrete structures in UAE based on ACI 318-19 Building Code.

Purpose of study:

Review and summarize outcomes of available studies and updated provisions/limitations of the ACI 318- 19, regarding the use of high-strength steel rebars in design of RC structural elements.

Identify and report the difference between ACI 318-08 and ACI 318-19, related to use of high-strength steel rebars in design of RC structural elements.

Prepare value engineering design sample of selected RC structural elements in a conventional floor slab to compare ES600 vs. B500B based on ACI 318-19. The samples include flexural design of slabs, flexural and shear design of beams, design of columns, and design of shear walls.

Re-design the selected structural elements using ACI 318-08 (if permitted by the ACI 318-08 Code) and compare the results with those based on the design with ACI 318-19.

Value Engineering Design Sample

Building Dimensions and Structural System

A reinforced concrete building is selected to present comparisons between ES600 Grade 600 and B500B when used to design various structural members. This example building is considered to be located in Abu Dhabi city. It consists of a ground story and seven typical stories. The building has equally spaced columns along the grid lines. The building dimensions are as follows:

• Length (east-west) = 42.0 m (4 bays @ 10.5 m)
• Width (north-south) = 20.0 m (5 bays @ 4.0 m)
• Ground story height = 4.0 m
• Typical story height = 3.0 m
• Total building height = 25.0 m

The structural system is a building frame system with a space frame providing support for vertical loads as per ASCE/SEI 7 (ASCE 2022). The considered Occupancy/Risk Category of the buildings is assumed as II. For this structural system, no limits are placed by ASCE/SEI 7 (ASCE 2022) on the building height if it is assigned to SDC ‘C’. The building flooring system supports nonstructural elements that are not likely to be damaged by large deflections. Ordinary reinforced concrete shear walls resist the seismic force in the north-south and east-west directions. Figures 1 and 2 show the selected building elevation and plan, respectively.

Material properties
• Specified concrete compressive strength 𝑓𝑓𝑐𝑐` = 35 MPa
• Modulus of elasticity per ACI 318M-19, Eqn. 19.2.2.1.b = 27806 MPa • Modulus of rupture per ACI 318M-19, Eqn. 19.2.3.1 = 3.67 MPa
• Specified steel yield strength:
– For ES600 Grade 600: 𝑓𝑓𝑦𝑦 = 600 MPa
– For B500B: 𝑓𝑓𝑦𝑦 = 500 MPa

Gravity Loads
• Dead Load, D:
– Self-weight (unit density, wc = 24.0 kN/m3, 2447 kg/m3)
– Additional superimposed dead Load, SD (F.C. + Non-Structural Walls/Partitions) = 4.8 kN/m2 • Live Load, L:
– Typical Floor = 3.0 kN/m2
– Roof (unoccupied) = 1.0 kN/m2

Outcomes of the Value Engineering Design Sample

Based on results of the value engineering design sample, the following conclusions are derived:
Savings in the range of 16.7% to 25% were observed in the flexural reinforcement of some sections of the one-way slab considered in the value engineering sample due to the use of ES600 Grade 600 steel rebars instead of B500B.

The number of steel reinforcing bars in some other sections of the one-way slab sample subjected to relatively low bending moments was governed by maximum allowable spacing to control the crack width per ACI 318-19. As such, the use of ES600 Grade 600 in these sections rather than B500B did not reduce the corresponding quantity of steel. In one section, the use of ES600 Grade 600 instead of B500B resulted in a higher steel quantity to satisfy the maximum spacing limit of ACI 318-19.

Savings in the range of 14.3% to 25% were observed in the flexural reinforcement of most of the sections of the beam considered in the value engineering sample due to the use of ES600 Grade 600 steel rebars instead of B500B. The number of rebars in one section was governed by maximum allowable spacing, which led to similar steel quantities for the used steel grades. The shear reinforcement of the beam sample was unaffected since the yield strength permitted in shear design is 420 MPa for both ES600 and B500B steel grades.

Savings of 8.3% and 16.7% in the longitudinal reinforcement were recorded for the shear wall and column considered in the value engineering sample due to the use of ES600 rather than B500B rebars. The ACI 318-19 requirements result in similar ties and spacing in the column reinforced with ES600 Grade 600 and B500B. The shear reinforcement in the shear wall was unaffected by the steel grade since the yield strength permitted in shear design is 420 MPa. The use of ES600 Grade 600 instead of B500B in the design of the column considered in the value engineering sample reduced the longitudinal steel ratio from 3.01% to 2.51%. Such a reduction in the steel ratio along with the use of fewer number of bars would mitigate probable congestion problems that might arise particularly at the joints. Generally, the use of fewer number of bars while satisfying the ACI 318-19 requirements would improve the placement and consolidation of concrete and reduce the placement cost.

The impact of replacing ACI 318-08 with ACI 318-19 when B500B (fy = 500 MPa) was used in the value engineering design sample was marginal. The flexural reinforcement in the one-way slab and beam considered in the value engineering design sample was unaffected by changing the edition of the ACI 318 Building Code. However, the temperature and shrinkage reinforcement in the one-way slab increased by 19% when the ACI 318-19 was used in the design. Both editions of the ACI 318 Building Code design resulted in similar longitudinal and transverse reinforcement in the column and shear wall considered in the value engineering design sample samples.

To get full study, click here: https://drive.google.com/file/d/1u4tChE7PwWYYRXUOO9cr24W-z1oGEMyW/view