CONTENTS 1.0 Overview of Post-Installed Rebar Technology in Malaysia - PDF document

18.09.2019 CONTENTS • 1.0 Overview of Post-Installed Rebar Technology in Malaysia • 2.0 Qualification of Post-Installed Rebar System • 3.0 Design Method – Rebar And Anchor Theory or Bonded Anchor Theory • 4.0 Design Recommendation – Strut and Tie Method and Simplified Design to Bonded Anchor Theory • 5.0 Demonstration of Design Software “ Profis Rebar and Profis Engineering” 1

18.09.2019 OVERVIEW OF POST INSTALLED REBAR TECHNOLOGY IN MALAYSIA Ir Ng Beng Hooi 24 th September 2018 POST-INSTALLING REBAR METHOD FOR CONCRETE CONNECTION Mechanical couplers Pre-cast rebar sets Perforated formwork Very attractive method Relatively easy to install Positioning of the bars for pre-fabricated slabs and straighten the bars mostly guaranteed Holes in formwork Risk of misplacement Risk of misplacement neutralizes reutilisation Localised reduction of Typically expensive Leakage of cement the bars cross-section solution reduces concrete quality Limited to smaller bars in the connection Limited to new projects Limited to new projects Limited to new projects 2

18.09.2019 POST-INSTALLING REBAR METHOD FOR CONCRETE CONNECTION Chiseling, Welding Cementitious grouts Adhesive mortars Load transferred directly Mixture quality ensured Low cost of grout per ml. to the existing bars by dispenser units Risk of creating concrete Can only be installed Small sized diameter cracks along the bars downwards or inclined and high bond strength Dubious control over the High dependency of the Drilling required mixture done on jobsite quality of the welding Higher cost of mortar Typical large drilling Welding can’t be done in diameter vs bar size per ml. unfavourable weather REBAR APPLICATIONS CAN BE CLASSIFIED INTO THREE MAIN CATEGORIES Lap Splices / Splicing Structural Joints Overlays 3

18.09.2019 THESE ARE EXAMPLES OF REBAR APPLICATIONS, WHICH HAVE THE OBJECTIVE OF CONNECTING MEMBERS Slab to Diaphragm Wall (slab to wall) New Slab/ Renovation (slab to wall) New Wall (wall to slab/ foundation) Balcony Extension (slab to slab) Upstands Wall tie connection 7 THESE ARE EXAMPLES OF REBAR APPLICATIONS, WHICH HAVE THE OBJECTIVE OF CONNECTING MEMBERS New Column/ Column extension Beam extension Corbel (Console) Close Opening (wall, slab, etc.) Strutting/ELS support with rebar Bridge Extension (slab to wall/slab) 4

18.09.2019 THESE ARE EXAMPLES OF REBAR APPLICATIONS, WHICH HAVE THE OBJECTIVE OF CONNECTING MEMBERS Office Building Staircases Residential Staircases Floor extension Wall Extension (wall to wall) Safety Barriers Slab to CBP Wall FROM POST-INSTALLED REBAR TO CONCRETE TO CONCRETE CONNECTION APPLICATIONS 5

18.09.2019 WE ALWAYS DESIGN ONLY REFER TO LOADING TABLE?? The design only consider Bond Strength for the Epoxy!!!! Is that Sufficient ??? REBAR APPLICATIONS CONSIST OF SHEAR, TENSION, MOMENT OR COMBINED LOADING. HENCE, DIFFERENT APPLICATION REQUIRES DIFFERENT EMBEDMENT DEPTH. Misaligned couplers Slab to diaphragm wall Slab to CBP wall Slab Extension Column Extension Beam to Column Pile cap Skin wall 6

18.09.2019 REBAR APPLICATIONS CONSIST OF SHEAR, TENSION, MOMENT OR COMBINED LOADING. HENCE, DIFFERENT APPLICATION REQUIRES DIFFERENT EMBEDMENT DEPTH. Slab to CBP wall Misaligned couplers Slab to diaphragm wall Slab Extension Beam to Column Pile cap Column Extension Skin wall A GENERIC REBAR DESIGN TABLE CANNOT BE USED FOR ALL REBAR APPLICATIONS V M N Anchoring of reinforcement Overlap joint for rebar Overlap joint at a foundation to cover the line of acting connections of slabs and beams of a column or wall tensile force N M End anchoring of slabs or beams Components stressed Components subjected to (simply supported) primarily in compression bending moment 7

18.09.2019 DIFFRENCE LOAD-TRANSFER MECHANISM BETWEEN POST- INSTALLED AND CAST-IN REBARS Cast-in rebars Post-installed rebars concrete mortar rebar rebar concrete Load is transferred by mechanical interlock provided by the At the mortar-concrete interface load is transferred by ribs. The mechanical interlock leads to compression struts adhesion and micro-interlock due to roughness of the drilled hole surface. The stiffness of the mortar is which lead to rotational tensile stresses perpendicular to the loading direction. responsible for the crack surface of the pull-out. DID WE DO PROPER DESIGN AND INSTALLATION FOR CONCRETE CONNECTIONS? Misaligned couplers Slab to diaphragm wall Slab to CBP wall Slab Extension Column Extension Beam to Column Pile cap Skin wall Post-Installed rebar widely used in both structural and non-structural elements. All of them are directly or in directly link to the safety of human being or economic investment 8

18.09.2019 UNDERSTANDING THE APPLICATION NEEDS AND DOING A PROPER DESIGN IS THE FIRST STEP All different influencing factors must be considered in the design Corrosion: Loading condition : Installation info: In-Door, Out-Door, Sea Side Static (cracked concrete), Geometry, or..... Seismic, Fire? Temperature, installation method CONSEQUENCE FOR NOT TREATING THEM SERIOUSLY Installation problem, structure pull out from concrete No proper design, anchor under design Do not consider for long term strength, deformation and durability problem 9

18.09.2019 CONSEQUENCE FOR NOT TREATING THEM SERIOUSLY No proper design, Concrete Edge Failure Brittle Concrete Failure. One example of failure on site due to embedment depth and spacing of post installed rebar. CONSEQUENCE FOR NOT TREATING THEM SERIOUSLY Anchor pull out after heavy rain, 35 tonne panel that collapsed onto Rainshelter Collapse the crane during erection 10

18.09.2019 CONSEQUENCE FOR NOT TREATING THEM SERIOUSLY Ceiling slab collapsed. Improper Installation and sustained load are the main reason Collapse of suspended concrete ceiling, a vehicle was partially crushed, killing a passenger ACCIDENTS HAVE SHOWN THAT FAILURE CAN HAPPEN AFTER YEARS OF INSTALLATION WASHINGTON, July 10 — The ceiling collapsed in one of Boston’s Big Dig tunnels a year ago, killing one woman, because builders used the wrong epoxy to hold the anchor bolts in place, the National Transportation Safety Board said Tuesday. “We’re talking about the wrong glue here, in effect,” said Kitty Higgins, one of the five members of the board, which said that the epoxy selected dried quickly but lost strength weeks later. On July 10, 2007, after a lengthy investigation, the National Transportation Safety Board found that epoxy glue used to hold the roof in place during construction was not appropriate for long-term bonding. [59] This was determined to be the cause of the roof collapse. 24 11

18.09.2019 WHAT DIMENSION SHALL BE CHECKED? Ultimate limit state Service limit state Durability Fastener shall sustain all load Fastener shall not Fastener shall remain fit for use actions during execution and deform to an taking into account the use inadmissible degree environmental conditions for the structure. …AND ACCIDENTAL EVENTS SHALL NOT BE OVERLOOKED Fire Seismic Anchor fasteners / Post-Installed Rebar have different behavior (load resistance and displacement) in these cases, a proper design has to be done accordingly! 12

18.09.2019 POST INSTALLED REBAR TECHNOLOGY IN MALAYSIA…… MANY PRODUCTS IN MARKET AND THE TECHNOLOGY KEEP IMPROVE 13

18.09.2019 ANCHORS CAN BE OF MANY DIFFERENT TYPES BUT THE INSTALLATION PROCEDURE FOLLOWS THE SAME STEPS Positioning Drilling Cleaning Setting Loading or or or or or + DRILLING METHODS AND CLEANING WILL EFFECT THE PIR PERFORMANCE Without percussion, for more Rotary drilling sensitive material sensitive material (e.g. masonry) Standard drill Hammer drilling Hollow drill bit Special drills Diamond drill Diamond drilling (reduced performance • Cuts through rebar vs hammer drill) • High precision • Low vibration & noise Diamond drill +roughening tool (equal performance vs hammer drill) 14

18.09.2019 CLEANING METHODS FOR HAMMER DRILLING e.g. Hilti HIT-HY 200 chemical anchor system Manual cleaning Drill 4x blow 4x brush 4x blow Install Compressed-air cleaning Drill 2x blow 2x brush 2x blow Install Automatic cleaning Drill Skip the cleaning & save up Drill Install to 50% time! Special non- cleaning systems Drill Drill Install SAFESET DRILLING GIVES YOU BETTER CLEANING PROCESS IN HAMMER DRILLED HOLES with Hollow Drill Bit Proper hole cleaning Bond strength, f bd [N/mm 2 ] Improper hole cleaning Hollow Drill Bit available up to 1500mm Displacement [mm] 15

18.09.2019 CLEANING METHODS FOR DIAMOND DRILLING e.g. Hilti HIT-RE 500 V3 chemical anchor system Diamond drilling ≥ 2x blow ≥ 2x blow Drill 2x flush 2x brush 2x flush 2x brush Install Diamond drilling + roughening Save time by skipping some cleaning steps! ≥ 2x blow Drill Roughen 2x flush 2x brush Install ROUGHENING TOOL (RT) ENSURES SAFE AND RELIABLE INSTALLATION IN DIAMOND CORED HOLES DD + RT Proper hole cleaning with DD+ Bond strength, f bd [N/mm 2 ] Proper hole cleaning with DD DD Improper hole cleaning with DD The RT roughens the sides of the smooth diamond cored hole allowing increased mechanical interlock between mortar and concrete. Displacement [mm] 16