Do It Right The First Time, Every Time And On Time. An Introduction to HERCULES LMK PT. Website:

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1 Do It Right The First Time, Every Time And On Time An Introduction to HERCULES LMK PT

2 Content 1.Introduction 2.Post-Tensioning System 3.Typical Stressing Procedure 4.Typical Preliminary Design 5.PT Slab Solution

3 Since 1994, HERCULES Group of Companies: Hercules Engineering (SEA) Sdn. Bhd. -Specialized in STRUCTURAL BEARINGS AND EXPANSION JOINTS Hercules Structural Systems Sdn. Bhd. -Specialized in BRIDGE LAUNCHING AND FORMWORK SYSTEM Hercules LMK PT (Far East) Sdn. Bhd. -Join-venture with Highway Specialist Construction System HiSCS S.A -Specialized in POST TENSIONING SYSTEM

4 QUALITY POLICY Heading towards customers satisfaction as our top priority. Provide comprehensive know-how and friendly service from a highly motivated team. Focus on applying new innovative technologies and contributing to high quality services respecting at the same time safety and environmental issues. Customers, Suppliers and Employees are essential to our business success and shall be treated with respect and integrity

5 Buy Malaysian, to advance Malaysia Having inspired by former Ketua Pengarah JKR, Tan Sri Omar Bin Ibrahim and Prof. Datuk Ir. Dr. Wahid Bin Omar and In the spirit of MALAYSIA BOLEH, HERCULES is the 1 st Pioneer in manufacturing the following Buatan Malaysia: Hercules Pot Type Bearings Hercules Spherical Bearings Hercules Finger Joints Hercules Modular Joints Hercules Hydraulic Dampers Now, HERCULES is targeting to be the 1 st Pioneer in making Post Tensioning System Buatan Malaysia

6 POST - TENSIONING ALL TYPES OF STRUCTURES & CONSTRUCTION METHODS BEAMS-BOX GIRDERS-VOIDED SLABS

7 POST - TENSIONING ALL TYPES OF STRUCTURES & CONSTRUCTION METHODS SEGMENTAL-LAUNCHING/CANTILEVERED

9 Pre & Post-Tensioning Principle STEEL ENDS FORMWORK PRE-STRESSING BED CAGE STRESSING CAGE CONCRETING TENDON CONCRETING TRANSFER OF STRESSING STRESSING RELEASING RELEASING First tensioning then concreting Pre-stressing bed First concreting then tensioning LMK PT SYSTEM Typically multi-strands encased in grouted ducts. Bonded systems = Grouted systems

10 PT System - LMK - Advantages Compact anchorages to facilitate the installation and grouting of the tendons. Anchorages design to satisfy the Design requirements of Int l Standards, European (EN - ETAG 013) & AASHTO LRFD-10, F.I.B. (International Concrete Federation) & PTI (Post Tensioning Institute) Recommendations. Wide selection of anchorages & jacks from 1 up to 37 strands (round) & 2 up to 5 strands (flat) allowing the Consultants to provide an economical design and specify improved technical feasibilities (proper cable deviations & losses). 37 different anchorage sizes and different types contributing to the Economy of the Design & Construction. Easy connection with standard or enlarged steel or plastic sheaths (flat and round).

11 Basic Calculations LMK PT System design data Tension at a distance (x) from the nearest stressing anchorage: x Where: ( kx) 0 x 0 = tension at the anchorage Δχ= Εlongation of cable x= cable length α= total angle of deviation (rad) μ= friction coefficient between strand and sheath (rad -1 ) [depends on tensioning force, bending radius, strand number, strand and sheath contact surfaces etc] k= coefficient of unintentional angular deviation (rad/m) [depends on sheath stiffness, way to install cables, distance between stirrups supports etc] Values: Bonded strand: µ= 0,20/rad, k= 0,009 rad/m steel ducts µ= 0,14/rad, k= 0,006 rad/m plastic ducts Unbonded strand: µ= 0,06/rad, k= 0,01 rad/m x x E 0 dx

duct Duct Strand Dead End (Restraint) Force Live End (Jacking) Force Dead End Force <

12 Loss of Pre-stress Friction Elastic shortening Initial losses (Short term) Shrinkage Creep Relaxation Time dependent losses (Long term) Anchor set Friction between strand and duct Duct Strand Dead End (Restraint) Force Live End (Jacking) Force Dead End Force < Live End Force Strand Duct Wobble and Curvature Effects Idealized Reality Duct/Strand Cross-Section

13 Basic Calculations LMK PT System design data Where E 195 GPa-KN/mm 2 Wedges draw-in: 4-5mm

14 Typical layout of the cable Grouting-venting valve Grouting-venting pipe Venting valve Venting pipe Venting saddle Adhesive tape

15 Typical Stressing Procedure Front Locking multi-strand Jack Positioning of stressing chair Positioning of jack Stressing (one or multiple phases) Locking off wedges Removal of jack

16 Typical Stressing Procedure Rear-Locking (Hollow) multi-strand Jack 1.Installation of anchor head & wedges 5.Stressing 2.Spacer installation 6.Jack s piston retraction & releasing 3.Jack installation 7.Jack s removal, grouting cap installation & grouting 4.Jack s rear hear & wedges installation

17 Typical Stressing Procedure-Monostrand Anchor head Wedge Wedge. Strand Anchor head & wedge installation Jack frontal ΔL Positioning of jack Stressing Case of locking off wedges Wedge draw-in 4-5mm Completion of tensioning works

18 Typical Phases-Preliminary Study of Design & PT Drawings

19 Typical Phases-Preliminary Geometry - Elevation Anchorages Types-Q/ties

20 Typical Phases-Preliminary Additional Data

21 Important Min Clearance Ducts diameter

22 PT SLAB SOLUTION Post-tensioned concrete slabs have become a major factor on the construction of floor systems for commercial and residential buildings of all types. In their two most popular forms (one way slabs, two way flat plates) they have been found to be economical for structural applications in parking structures, apartment buildings, office buildings hospitals and industrial buildings of both the high rise and low rise type. One of the main reasons contributing to the development of this technology is that post-tensioning can solve simultaneously weight, deflection and cracking problems, which can arise in the conventionally reinforced slabs.

23 PT SLAB SOLUTION When can we use PT slab? -Every time we have a plain concrete slab. -Every time Architects need structures to be built with very peculiar shapes and proportions between thicknesses and spans (e.g. balconies with long spans keeping small thickness) -Every time we want to reach efficient use of materials combining performances and money savings.

24 PT SLAB SOLUTION PT reinforcement Vs standard steel Once the slab thickness is fixed, deflection is linked to it through coefficients which taking into account materials characteristics, spans and loads. The use of PT unbonded cables allows to apply an external action that retrieves the elastic deformation of the system. The same cables have a resistance more than 3 times the resistance of normal steel (breaking load 1860 N/mm 2 instead of 550 N/mm 2 ). It has been witnessed in many experimental tests that the unbonded PT slab has a load bearing capacity 4 to 5 times the concrete failure (after concrete failure the slab-cables system works like a suspended bridge) that means extra SAFETY.

25 PT SLAB SOLUTION Advantages for the Designer/Consultant -It is possible to solve many structural problems, from deflection of thin slabs to high loaded slabs. -The Designer/Consultant has the instruments to satisfy almost all of the structural-architectural problems/requests. -It is possible to optimize the use of modern materials (high strength / light weight concrete) limiting their defects (low traction resistance).

26 PT SLAB SOLUTION Why we have to use PT slab? Because the system has direct (less concrete and standard steel) and indirect (thinner foundations contribute to the reduction of the dead load) economical advantages.

27 PT SLAB SOLUTION Why we have to use PT slab? Improvements and simplifications in post-tensioning hardware and field methods, made post-tensioned slab construction easy for the contractor as conventionally reinforced slabs. Improvements in forming systems have enhanced the overall economics of cast-in- place slab construction. Testing programs on post-tensioned slabs, greatly expanded the understanding of their behavior and led to improved code criteria and more economical and safe Designs. The combination of PT with standard reinforcement results in considerable savings and advantages such as minimum crack distribution and higher strength of concrete slabs.

28 PT SLAB ADVANTAGES DESIGN Direct Advantages Reduction in slab thickness Larger spans (and reduction of columns) Reduction in slab weight High limitation of crack widths High deflection limitation Flexibility of the system Related Further Advantages Floor to floor distance reduction Savings on total building height Reduction of construction volumes and consequent energy needed for heating, cooling living spaces Different opportunities for ceiling final finishing Increase of free space available More architectural opportunities Savings on vertical structural bearing members and foundations. Reduction of seismic mass Improvement of durability and concrete behavior Improvement of serviceability for all structural members Different form turning around holes, non linear surfaces or round profiles

project during the construction Related Further Advantages Easier materials placing and handling. Possible earlier formworks removal.

29 PT SLAB ADVANTAGES CONSTRUCTION Direct Advantages Reduction of steel reinforcement and arrangement simplification High deflection limitations due to concrete shrinkage and creep High repeatability from floor to floor / quick rotation of formworks Flexibility of the project during the construction Related Further Advantages Easier materials placing and handling. Possible earlier formworks removal. Reduction of erection times Reduction of formworks sets Improvement of constructability Possible changes of the project during the construction

This assembly is positioned, and then the concrete is casted, similar to standard reinforced concrete.

30 PT SLAB SOLUTION There are two types of PT systems: bonded and unbonded. UNBONDED Unbonded systems use strands surrounded with special corrosion-inhibiting grease and encased in waterproof plastic sheaths. This assembly is positioned, and then the concrete is casted, similar to standard reinforced concrete. BONDED With a bonded system, before the casting of concrete, empty steel or plastic ducts are positioned in the formed area and attached to the anchorages at both ends of the tendon. After casting & maturing of concrete, strands are threaded through the ducts, tensioned and then ducts are grouted filled with a special cement grout designed to prevent corrosion and contribute to stress distribution.

31 PT SLAB SOLUTION UNBONDED BONDED

BONDED The size of the duct used in a bonded system and the minimum cover that must be provided may control the maximum eccentricity that can be achieved.

32 PT SLAB SOLUTION The most efficient prestress design is when the prestressing tendon is positioned eccentrically in the concrete section on a curved profile or deflected from a straight line. BONDED The size of the duct used in a bonded system and the minimum cover that must be provided may control the maximum eccentricity that can be achieved. The ducts are formed by spirally-wound or seam folded galvanized metal strip or PP/HDPE plastic ducts. The limit on the curvature or profile that can be achieved with the prestressing tendons is dependent on the flexibility of the ducts. The ducts have to be grouted after stressing, which introduces a further time into the construction process.

33 PT SLAB SOLUTION UNBONDED In an unbonded system the tendon is not grouted and remain free to move independently of the concrete. This has no effect on the serviceability design or performance of a structure under normal working conditions. It does, however, change both the design theory and structural performance at the ultimate limit state, which is preceded by larger deflections with fewer, but larger, associated cracks, than with an equivalent bonded system. Thus, with an unbonded system there are obvious visual indications that something is wrong well before failure occurs. In an unbonded system, tendons can be located close to the surface of the concrete to maximize the eccentricity. Tendons are flexible and can be easily fixed to different profiles. They can be displaced locally around holes, and to accommodate changes in slab shape. The stressing operation is simple and with no grouting, is suited to a speedy construction method.

34 PT SLAB SOLUTION PT slabs are designed to withstand the usual imposed floor loads such as vehicle wheels, racking posts, pallets and so on. The main forms of construction are:

35 PT SLAB SOLUTION

36 PT SLAB SOLUTION

37 PT SLAB SOLUTION A particular design feature of post-tensioned slabs is that the distribution of tendons on plan within the slab does not significantly effect its ultimate strength. There is some effect on strength and shear capacity, but this is generally small. This allows an even prestress in each direction of a flat slab to be achieved with a number of tendons layouts. Here some common layouts of unbonded tendons in flat slab. Holes through prestressed slabs can be accommodated easily if they are identified at the design stage. Small holes (less than 300x300mm) can generally be positioned anywhere on the slab, between tendons, without any special requirements. Larger holes are accommodated by locally displacing the continuous tendons around the hole.

38 PT SLAB SOLUTION

39 PT SLAB SOLUTION

contributing to the most appropriate constructional concept from Technical & Economical point of view. A proper Design = Value Engineering.

40 Accomplishment of PT Works - Study & Evaluate Design Parameters : 30% - Installation-Inspection prior of Concreting : 40% - Tensioning : 20% - Grouting : 10% The Specifications and applicable Standards should be considered only as a TOOL for the Consultant to define the limits and the frame of designing factors contributing to the most appropriate constructional concept from Technical & Economical point of view. A proper Design = Value Engineering. ELIMINATE THE UNNECESSARY. Avoid cost which provides neither use, nor life, nor quality, nor appearance, nor customer features BUT without affecting the end quality of the product.

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