Bsrm Steels Limited · DSEBD:BSRMSTEEL
Bsrm Steels — Bangladesh Steel Re-Rolling Mills (BSRM) — Technical Presentation (March 2016)
39 slides from Bsrm Steels's technical presentation, March 2016
Slide 1: Strength and Ductility of Reinforced Concrete Highway Bridge Pier
Strength and Ductility of Reinforced Concrete Highway Bridge Pier Engr. Md. Abdur Rahman Bhuiyan, PhD Associate Professor Department of Civil Engineering Chittagong University of Engineering and Technology Chittagong-4349 National Seminar on Performance Based Design of Reinforced Concrete Structures
Slide 2: Introduction
Introduction Highway bridges are the most common and critical civil infrastructure components of a transportation network as they play important role in ● evacuation and emergency routes for rescues, ● first-aid, ● firefighting, ● medical services and ● transporting disaster commodities during and a
Slide 3: Introduction (contd…)
Introduction (contd…) The recent earthquakes, such as ● the 1994 Northridge earthquake, ● the 1995 Great Hanshin earthquake , ● the 1999 Chi-Chi earthquake, ● the 2008 Sichuan earthquake, ● the 2010 Chile earthquake, and ● the 2010 Haiti earthquake, have shown the inadequacy of strength of the exist
Slide 4: Damage Scenario
Damage Scenario Flexural failure at the base of bridge pier of the Shear Failure of flared column in the 1994 Hanshin expressway in the 1995 Kobe earthquake Northridge earthquake Unseating of simply supported link span in the Bond failure of lap slices of bridge pier in the 1995 Kobe earthquake Loma
Slide 5: Damage Scenario (contd…)
Damage Scenario (contd…) Flexural-shear failure at pier midheight in the Failure of flexural plastic hinges in bridge piers in 1995 Kobe earthquake the 1994 Northridge earthquake Shear Failure of flared column in the 1994 Collapse of the Hanshin expressway in the 1995 Northridge earthquake Kobe eart
Slide 6: Damage Scenario: at a glance
Damage Scenario: at a glance ● flexural failure of piers of the Hanshin Expressway in the Kobe earthquake in 1995 ● bond failure at the base of a RC columns attributable to lap slice in the Loma Prieta earthquake in 1989 ● the flexure-shear failure of bridge piers initiated at bar cutoff locations a
Slide 7: Philosophy of Seismic Design of RC Bridges
Philosophy of Seismic Design of RC Bridges Basic concept of design philosophy and seismic performance criteria are more or less similar among seismic codes in Japan, the USA, the EU and New Zealand and some other countries that ● for small-to-moderate earthquakes, bridges should be resisted within t
Slide 8: Development of Seismic Design Specification of Highway Bridge: 1926
Development of Seismic Design Specification of Highway Bridge 1926 Design Specification: ● The first seismic provisions for highway bridges were introduced in 1926 after destructive damage of the 1923 Great Kanto earthquake ● It only specified a seismic lateral force of 20% of the gravity force; no
Slide 9: Development of Seismic Design Specification (contd.): 1971
Development of Seismic Design Specification of Highway Bridge (contd.) 1971 Design Specification: ● The first comprehensive seismic design provisions were issued by the Ministry of Construction in 1971 in the form of the Guide Specification for Seismic Design of Highway Bridges ● It was specified in
Slide 10: Development of Seismic Design Specification (contd…): 1980
Development of Seismic Design Specification of Highway Bridge (contd…) 1980 Design Specification ● The 1971 Guide Specification for Seismic Design were revised in 1980 to become the Design Specification for Highway Bridges
Slide 11: Development of Seismic Design Specification (contd…): 1990
Development of Seismic Design Specification of Highway Bridge (contd…) 1990 Design Specification: ● The 1980 Design Specification was revised in 1990 ● Various major revisions were included in the revised version by incorporating the ductility method as a checking tool
Slide 12: Development of Seismic Design Specification (contd…): 1995
Development of Seismic Design Specification of Highway Bridge (contd…) 1995 Design Specification ● Forty days after the Hyogo-ken nanbu (H-k- n) earthquake, the Japan Ministry of Construction issued the Guide Specification for reconstruction and repair of highway bridges which suffered damage in the
Slide 13: Development of Seismic Design Specification (contd…): 1996
Development of Seismic Design Specification of Highway Bridge (contd…) 1996 Design Specification: ● Although the 1995 and 1996 Specifications are essentially the same in concept, modifications and upgrading were included in the 1996 Specification, most importantly, the check on the Ductility was upg
Slide 14: Development of Seismic Design Specification (contd…): 2002
Development of Seismic Design Specification of Highway Bridge (contd…) 2002 Design Specification ● Because of the unsatisfactory performance of bridges in the 1995 Kobe earthquake, the Japanese Design Specifications of Highway Bridges was revised in 1996. ● The code was further revised in 2002 based
Slide 15: Performance Based Design
Performance Based Design ● Design for seismic resistance has been undergoing a critical reappraisal in recent years, with the emphasis changing from “strength” to “performance”. ● For most of the past 70 years – the period over which specific design calculations for seismic resistance have been requ
Slide 16: Performance Based Design (contd.)
Performance Based Design (contd.) The performance-based design concept is that the necessary performance requirements and the verification policies are to be clearly specified
Slide 17: Performance Based Design (contd.)
Performance Based Design (contd.) ●The performance-based design distinguishes itself from the conventional design approach by specifying ●Objectives (or Goals) and Functional Requirements (Functional Statements), which are qualitative, and ●specifying or referencing Performance Requirements (or Crit
Slide 18: Performance Based Design (contd.)
Performance Based Design (contd.) Hierarchy of performance-based design
Slide 19: Seismic Performance Criteria (JRA, 2002)
Seismic Performance Criteria (JRA, 2002) ● the Level 1 earthquake is the moderate ground motion with high probability of occurrence and ● the Level 2 Earthquake is strong ground motion with low probability to occur ● Type I earthquake: the Kanto earthquake ● Type II earthquake: the Kobe earthquake
Slide 20: Seismic Performance Criteria (ATC 32)
Seismic Performance Criteria (ATC 32) Ground Motion Service level Damage level (GM) Ordinary Important Ordinary Important Bridges Bridges Bridges Bridges Functional Immediate Immediate Repairable Minimum evaluation GM Damage damage Safety evaluation Limited Immediate Significant Repairable GM damage
Slide 21: Verification Methods of Seismic Performance
Verification Methods of Seismic Performance It is the fundamental policy of the verification of seismic performance that the response of the bridge structures against design earthquake ground motions does not exceed the determined limit states.
Slide 22: Structural Deformation Capacity (AASHTO-LRFD)
Structural Deformation Capacity (AASHTO-LRFD)
Slide 23: Failure mode, lateral strength and ductility capacity of a bridge pier
Failure mode, lateral strength and ductility capacity of a bridge pier ● The pier strength and the design ductility factor of pier can be determined based on the failure mode Pe Py = Pu Dy Dm : flexural failure : shear failure after flexural yielding : shear failure
Slide 24: Failure mode, lateral strength and ductility capacity (contd..)
Failure mode, lateral strength and ductility capacity of a bridge pier (contd..) The allowable lateral capacity is provided as flexural failure + shear failure after flexural damage shear failure The allowable displacement ductility is provided as flexural failure shear failure after flexural damage
Slide 25: Evaluation of Lateral Strength and Ductility of RC Bridge Pier
Evaluation of Lateral Strength and Ductility of RC Bridge Pier The cross-section of the pier is 7 m ×1.9 m The height of the pier is 11.5 m The weight of the superstructure and pier are, respectively, 990 tonf and 347 tonf .
Slide 26: Evaluation of Lateral Strength and Ductility of RC Bridge Pier (contd…)
Evaluation of Lateral Strength and Ductility of RC Bridge Pier (contd…) Using the moment-curvature plot shown in Figure (left) and the Equation presented below, the top displacement of the bridge pier can be obtained Finally, the force-displacement relationship at top of the bridge can be obtained f
Slide 27: Evaluation of Lateral Strength and Ductility of RC Bridge Pier (contd…)
Evaluation of Lateral Strength and Ductility of RC Bridge Pier (contd…) Moreover, a professional software (for example, Seismostruct 2011) can be used to derive the force-displacement relationship at top of the bridge pier by conducting push-over analysis
Slide 28: Seismic Performance of a reinforced concrete bridge pier under strong seismic event
Seismic Performance of a reinforced concrete bridge pier under strong seismic event
Slide 29: Ductility of RC Structures
Ductility of RC Structures ● Material Ductility ● Curvature (section) Ductility ● Element Ductility ● Structural Ductility
Slide 30: Material Ductility
Material Ductility » Unconfined concrete: N — Negligible tensile strength — Higher compressive strength (f,,) => lower ductility — Ultimate strain ¢,,=0.0035 (EC 2) 8 STRESS (MPal i « Reinforcing steel: — Higher strength => lower ductility — Elongation at maximum force: €,,20.075 for DCH (EC2 & P100
Slide 31: Material Ductility
Material Ductility = Concrete compressive IZA ikea stress levels approaching lL ame, | AAA crushing strength => high A ah lateral tensile strains meting C— fee = Lateral restrain provided by — — transverse (together with Yy, AT longitudinal) reinforcement tial YAZIA => confinement arr « Effect of co
Slide 32: Curvature Ductility
Curvature Ductility « Rotation in plastic hinges - the most desirable source of inelastic deformations = Curvature - rotation per unit length under bending moment « Yield curvature: yielding of reinforcement or attainment of high concrete strains (¢,=0.0015) |. 1 | do | { _ BY | E ly By duane Bm pEy
Slide 33: Curvature Ductility
Curvature Ductility « Ultimate curvature - corresponding to significant reduction of moment capacity (below 85% of maximum bending moment - EC8), usually controlled by attainment of ultimate concrete strain e,,, = Section ductility: 1=9,,/9, « Factors affecting section ductility: Ultimate concrete s
Slide 34: Element Ductility
Element Ductility Rotations in plastic hinges - distributed over a finite length: plastic hinge length Element ductility: 4,=A/A, Displacements A, and A can be obtained by integrating the curvature over its height tes rh 4 Ae I / { |i - _ Basak" | | ny E = <p == = ’ ws . i = onus Yield = is fa) {b}
Slide 35: Element Ductility
Element Ductility = Example: damage of columns of the same building (Olive View Hospital) during the San Fernando earthquake, California, USA, from February 9, 1971 adequate transverse reinf. inadequate transverse reinf.
Slide 36: Element Ductility (Column)
Element Ductility (Column) » Strong column - weak beam design philosophy «= However, plastic hinges in columns not precluded completely > columns should be detailed for ductile behaviour in potential plastic hinges (column ends) «= Columns: bending, shear force, axial force = Ductility provided by:
Slide 37: Structural Ductility (Frame)
Structural Ductility (Frame)
Slide 38: ACI 318-02 special provisions for seismic design of RC structures
ACI 318-02 special provisions for seismic design of RC structures Goal: ● to ensure adequate ductility under inelastic displacement reversals brought on by earthquake loadings How to achieve the goal? ● this goal can be achieved by providing concrete confinement and inelastic rotation capacity in RC
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