SECURITY AND SAFENESS NH91 1 CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG 1 BRIDGE; SANG TRANG 2 BRIDGE CONSTRUCTION METHOD STATEMENT FOR SUPERSTRUCTURE TABLE OF CONTENTS CHAPTER I CONSTRUCTION TECHNOLO[.]
NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE CONSTRUCTION METHOD STATEMENT FOR SUPERSTRUCTURE TABLE OF CONTENTS CHAPTER I: CONSTRUCTION TECHNOLOGY OF PRESTRESSED RC BEAD I 33M I MATERIALS II CASTING YARD AND FORMWORK III CONCRETE WORKS IV TENSIONING PRESTRESSING STEEL V QUALITY ASSESSMENT AND INSPECTION OF I BEAM 33M CHAPTER II: MANUFACTURING TECHNOLOGY OF I 20.7 M BEAM CHAPTER III: INSTALLATION OF I BEAMS FOR TRA NOC, SANG TRANG 1, SANG TRANG BRIDGES I CONSTRUCTION REQUIREMENTS II INSPECTION OF QUALITY III THE SEQUENCE CONSTRUCTION OF THE SUPERSTRUCTURE FOR TRA NOC, SANG TRANG 1, SANG TRANG BRIDGES CHAPTER IV: CONSTRUCTION METHOD OF OTHER WORK ITEMS I ELASTOMERIC BEARINGS AND STEEL DOWELS II CONSTRUCTION OF CROSS BEAMS III CONSTRUCTION OF PARAPET IV CONSTRUCTION OF EXPANSION JOINTS V BRIDGE DECK WATERPROOFING MEMBRANE VI CONSTRUCTION OF ASPHALT CONCRETE VII CONSTRUCTION OF BRIDGE DRAINAGE 1/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE 2/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE CHAPTER I: CONSTRUCTION TECHNOLOGY OF PRESTRESSED RC BEAD I 33M I Materials The materials must ensure technical requirements in accordance with current standards During storage, transportation, materials must be stored to avoid contamination or mixed grain size and type When the above cases happen, solutions must be carried out to to ensure the stability of quality Table reference standards: TCVN 6284-1:1997 Reinforcing Steel 22TCN 272-05 Specification design ASTM A 421 - 91 Un-coated Stress Relieved Steel Wire for Pre-stressed Concrete ASTM 416 - 90a Steel Strand, Un-coated Seven Wire Stress Relieved Strand for Prestressed Concrete ASTM A722M-07 Uncoated High Strength Bars for Pre-stressing Concrete standard for Bridge General Requirements High tensile strength steel is low relaxation type 270, in accordance with ASTM A416-99, the required criteria as the following table: Diameter Tensile Strength Yield Strength Elasticity Modulus (MM) (MPA) (MPA) (MPA) 12,7 1860 1670 195.000 - Testing for prestressed cable must comply with the requirements of the ASTM and instructions of the Supervision Consultant - High tensile strength steel wire shall be stress relieved and shall conform to the requirements of TCVN 684-1:1997 or ASTM A 421-91 or equivalent “Un-coated Stress Relieved Steel Wire for Pre-stressed Concrete” - High tensile steel strand with low-reaction shall be weld free and stress relieved after stranding and shall conform to the requirements of TCVN 684-1:1997 or ASTM A 416-90a or equivalent “Steel Strand, Un-coated Seven Wire Stress Relieved Strand for Pre-stressed Concrete” - High tensile steel bar shall be stress relieved and shall conform to the requirements of TCVN 684-1:1997 or ASTM A 722 or equivalent 3/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - Manufacture’s test certificate for breaking strength shall be obtained for each delivered coil or bundle and a stress/strain diagram shall be obtained for every fifth coil or bundle Copies of these shall be transmitted to the Engineer Material Requirements 2.1 Reinforcement Reinforcement must comply with article 5.5 “Reinforcing Steel” 2.2 Anchorages - The Engineer shall approve all anchorage assemblies - All post-tensioned pre-stressing steel shall be secured at the ends by means of approved permanent type anchoring devices The Contractor shall submit information and details, including test certifications to the Engineer for approval - End anchorage devices (stress and dead anchors) shall be designed and manufactured for type of tendons to be used They shall have a previous service record of functioning and durability in use on similar type work - The anchorage details for external tendons should provide complete removability of the tendon at any stage of the design life of the structure without modification or damage to the structure The prestressing system should have the ability to replace the removed tendon via the same anchorage casting within the diaphragm segment of the span - All anchorage devices for post-tensioning shall be capable of holding the pre-stressing steel at a load producing a stress of not less than 95 percent of the guaranteed minimum tensile strength of the prestressing steel - Fixed anchorage’s for tendons in precast beams shall be of a steel bearing plate type while all remaining anchorage’s shall be those capable of adjustment by means of a threaded anchor head and ring nut - It shall be the responsibility of the Contractor to determine the required bursting reinforcements in the local zone for the particular shape and design of the anchorage devices proposed - All externally exposed steel parts shall be protected from corrosion All threaded parts and fittings shall be protected by greased wrappings or plugs until used Anchorages shall be kept free from dirt, mortar, loose rust or other deleterious materials Damaged anchorage parts shall not be used 2.3 Ducts for internal Tendons - Ducting for internal tendons shall be fully compatible with the proposed prestressing system The ducting shall form an airtight and watertight barrier to the tendons and shall be fabricated from corrugated galvanized sheet steel or semi-rigid conduit Duct area shall be at least times the net area of the post-tensioning steel - Minimum duct thickness shall be as follows: 4/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - 26 gauge for duct dia less than or equal to 67 mm - 24 gauge for duct dia greater than 67 mm - 31 gauge for bar tendons - Ducts shall have grouting connections at each end and shall have vent/drains at all intermediate high and low points, to the approval of the Engineer 2.4 Grout for Ducts - Unless otherwise directed or approved by the Engineer as a result of grouting trials, the grout shall: - Consist only of ordinary Portland cement, water and expansive admixtures approved by the Engineer and used in accordance with the manufacturer’s instructions - Have water to cement ratio, as low as possible consistent with the necessary workability, and under no circumstances shall the water: cement ratio exceed 0.40 - Not be subject to bleeding in excess of per cent after hours, or per cent maximum when measured at 30oC in a covered glass cylinder approximately 100 millimeters diameter with a height of grout of approximately 100 millimeters, and the water shall be re-absorbed by the grout during the 24 hours after mixing - Not contain admixtures containing chlorides, nitrates or similar electrolytic conducting materials - The minimum compressive strength of a test cylinder shall be 20 Mpa at 28 days 2.5 Concrete 3.1 3.2 Concrete shall be inconformity with section 5.1 “Concrete and Conscrete Structures” of the Specifications Storage of materials High tensile strength steel - The High tensile strength steel shall be carefully packaged to avoid moisture rust, during transportation to use the tight canvas, not to stick to oil, grease, salt, chemical fertilizers Transportation of high strenth steel shall not be associated other cargos - While loading and unloading from vehicles to the stock yard or otherwise, it is not permitted to throw down from above, not to be twisted and scratched Any defect that damages the high tensile strength steel wire shall be the reason to check and it may be rejected - The High tensile strength steel must be stored in the tall warehouse, ventilation, not wet, when high tensile strength steel is pilied up, the steel must be placed on the even platform at least 0.2 m high from the ground and should not pile up exceed 1.50 m Reinforcement and built-in structures - All the steel before using must be checked including the documents for labels, codes and categories 5/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE 3.3 3.4 3.5 II - Steel must be separated in each type of diameter for easy use and checked as needed, not to adhere oil, grease, paint or other chemicals - Steel must stored on the timber shelf so that the entire bars is higher than the ground at least 0.3 m - Prior to installation, the fabricated built-in items must be inspected for correction of marks, steel code, drawings and specifications - During storing, materials must be separated, absolutely not adhere greasy, asphalt, if adhering contaminants, materials must be cleaned Storage of cement - When transporting cement to the storage, canvas must be used to cover to avoid rain If the cement be moistured, put these cement bags aside and have plan to use in advance - Cement placed in the storage, the storage ground must be tall, no stagnancy, no leaking from all directions around Cement storage shall be at least 0.2 m higher than the background and placed on the airy floor - The cement bags pile no more than layers, the bags are stored away from a wall about 0.3 m, between the rows of cement bags must have walkway to transport - To ensure no degradation of cement, the time from production to use 70 days Storage of aggregates - Aggregate for concrete of beam must be stored separately, not mixing with aggregate of other concrete components - Sand, stone storage areas must meet the requirement hereunder: + There is no stagnant water, have drainage ditch around + There are layers of compacted crushed stones so as separate with mud + During use, the damaged surface must be remedied in time - The amount of sand and rock must be stored enough quantities for production of the beam - Each delivery of sand, stone must be checked for the dirt, flatness grain content, and weathering rock content Storage of additives - Additives must be contained in the sealed barrel, labeled outside, and production time, meet requirements of the Specifications - The closed additive barrel may be stored outdoor or indoor, others must be kept in covered storage Additives used in concrete batch shall be calculated in dose Casting yard and formwork Number of Casting bed and formwork 6/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - I 33m beams of Tra Noc and Sang Trang Bridge are the posttensioning concrete beams - Quantities of I 33m beams: - Tra Noc bridge: 70 beams Sang Trang 2: 43 beams All I33m beams will be casted in Casting Yard at Km6+000 The Contractor will organize 04 casting bed for I 33m beam and 01 concrete mixing plant to supply concrete Service road will be provided for transportation of concrete The Contractor will fabricate: 02 sets of side formwork; 04 set of bottom formworkd will be fixed on 04 casting bed Design of casting bed and formworks 2.1 Casting bed 2.2 - Structure of casting bed must ensure convenience for placing reinforcing steel and pre-stressing steel to get enough space for the erection and removal of formwork, concrete supply, placing concrete and lifting casted beams then transport to the storage yard - The position of the casting yard must be in high places to ensure good drainage, absolutely no settlement - The bottom of the casting yard shall be treated by wooden pile 4.5m, 18 piles/m2, sand bedding, crushed stone 20cm, concrete C20 thickness 10cm - Shaped steel 2C200 will be laid at every distance of 1m.on the floor of casting bed for supporting bottom formwork Total length of casting bed is 33.8m Formwork - Fabrication and erection of formwork shall be in the correct position It should be easy to erect and remove the formwork The joints must be parallel or perpendicular to the beam axis and to be sealed tight enough to prevent cement motar from leakage - Formwork consists of two parts: bottom and side formworks + Bottom formwork with a total length of 33 m is made plate steel of mm thickness, having the vertical and horizontal stiffeners made of steel Bottom formwork is divided into small plates After installing into the casting bed, the plates will be connected by bolts + Side formwork: made of steel plate thickness mm, reinforced with V shaped steel Vibrators attach outside at even distance to be used when concreting + After the completion of installing vibrator into the side formwork, trial operation is needed to check the stiffness of the formwork, status of vibrator and stability + Technical requirements of formwork: 7/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE * * * The firmness, durability, watertightness The evenness Tolerance of dimensions within the allowable range Construction 3.1 Casting bed 3.2 3.3 - Remove soft soil, level ground and compact to K95 - Driving of wooden piles 4.5m length, 18 piles/m2 - Place sand bedding - Lay crushed stone 20cm thickness - Pour 10cm concrete C20 to make surface of casting bed - After placing concrete curing in days Bottom formwork - Shaped steel 2C200 will be laid at every distance of 1m.on the floor of casting bed for supporting bottom formwork - Install bottom formwork plates of 3m length and connect by bolts - After welding done, detailed dimensions and flatness of each plate will be checked, fix the error before starting next works Side formwork - Side formwork will be fabricated by plates of 3m length Connections of plate will be made by bolts; - Before casting the first beam, side formwork will be erected with bottom formwork to generally check all formwork of I beam - Installing the vibrators to the side form by bolts - Turnbuckle will be used for closing on the top of side formwork - Turnbuckle will be installed in the two sides for supporting side formwork; - Side formwork will be installed only when completion of reinforcing steel and ducts Installation of bottom formwork with casting bed - Each plate of the bottom formwork is linked with casting yard, may place and pump cement grouting linking for each section before the joint welding and then pumping cement grouting for the next section, or put the entirely then pumping cement grouting The sequence of construction as follows: + After fabrication of the bottom formwork plate meets the requirements then each plate will be installed on the casting yard Link all bottom formwork plates by butt weld then grinding welds smoothly Use the turnbuckles to tighten the bottom formwork with the casting yard Check the overall size of the bottom formwork installed + Pumping cement mortar M100 into the gap between the bottom formwork and the casting yard 8/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE + III Repeat the above sequence of construction for the next segment - Set and associate support structures for wall wing together with casting yard - Set and associate jacking beam with the casting yard - Check the overall size of the entire bottom formwork with casting yard Beam storage yard - Fabrication yard should have a suitable length The yard is compacted to K95 20cm of crushed stone will be placed on the top - The beams are chocked with concrete sleepers, dimensions 90x40x40 cm or equivalent at the location 150 cm from the beam head - Moving or transfering beams from casting bed to storage yard by gate gantry, with the lifting capacity of 80 ton or more than CONCRETE WORKS Concrete is produced by batching plant at construction sites and transported to the construction site by truck agitators Prior to delivery of concrete, the quality control and testing of concrete must be conducted along with delivery records With different structures: measures for placing concrete are shown in the drawings of the construction methods Components of concrete - The concrete beams C40 are designed for beam I33m and I20.7m - Adjusting concrete mix design at the site will be conducted on the principle that water / cement ratios will no be changed When aggregates is moist, it should reduce the amount of mixing water, keep the required slump Manufacture of concrete mix Manufacturing concrete mix by batching plant Mixing concrete process shall comply with the following provisions: - When mixing concrete, materials must be weighted accurately Moisture content of sand and stones must be conducted inspection regularly to adjust the amount of aggregates and water use - Allowed tolerance when weighing shall not exceed the allowed values - The accuracy of measuring equipment must be calibrated During weighing, regular monitoring to detect and correct promptly Transportation of concrete mix - Batching plant is located next to casting yard so the transportation is very convenient and initiative in any situation Placing concrete Placing concrete must meet the following requirements: - Closely monitor the status of formwork during the construction process to settle in time if problems occur 9/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - When it rains, covering to prevent concrete from raining - Only to place concrete when the ambient temperature satisfying º C ≤ T ≤ 30ºC - The placing concrete must follow instructions of the Engineer Compacting concrete - Different kind of vibrators may be used, but to ensure that after the concrete is compacted the surface free from honeycombing - Compaction time for each location must ensure that the concrete is thoroughly compacted - Notes when compacting concrete: - + When using poker vibrators, moving distance not exceeding 1.5 times the radius of the vibrator effects Distance to side formwork from 5-10cm, penetrating into the under concrete layer 5-10cm, when finishing each vibration of a place just to withdraw vibrator up, avoid colision of vibrator into formwork, reinforcing steel and right in place buried parts + When using the vibrator must base on the figure and shape of the structure and vibrator functions, through testing to determine the distance of the vibrators + When the concrete stop subsidence, no air bubbles, surface wellcompacted, then stop vibrating The placing concrete must be conducted continuously If interruption occurs, the interupption time must be less than the time of initial setting, or less than the allowable time for re-vibrating the earlier placed concrete Curing concrete - After placing conrette, concrete must be cured in conditions of humidity and needed temperature for curing and preventing the harmful effects during curing of the concrete - Moisture curing: is the process for keeping concrete with moisture necessary to the setting and hardening after shaping During curing, the concrete shall be protected against mechanical impacts such as vibration, shock forces, loads and impacts, which are likely to cause other damage Checking of the concrete samples - The limit compressive strength of concrete must be taken through testing samples Each casted beam takes 09 samples, 03 samples tested after 72 hours (3 days), 03 following samples is tested after days, 03 remaing samples to determine the 28-day strength The testing sample is cylinder 150x300 mm or cube 150x150x150 mm - The quality of materials used for mixing concrete must be tested, the test methods must conform to the relevant regulations IV Tensioning Prestressing Steel Preparation works 1.1 Quality Ceritificates 10/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE 1.4 - Where members consist of jointed elements the strength of transfer of the jointing material shall be at least equivalent to the specified transfer strength of the member - The Contractor shall establish the datum point for measuring extension and jack pressure to the satisfaction of the Engineer Allowance shall be made for the friction in the jack and anchorage for pull-in of the tendon during anchorage - The tendons shall be stressed at a gradual and steady rate until the required extension and tendon load is reached or is approved by the Engineer The sequence of stressing shall be as shown on the drawings or directed by the Engineer - The force in the tendons shall be obtained from readings on a load cell or pressure gauge incorporated in the equipment and the extension of the tendons measured The extension of the tendons under the approved total forces shall be within the limits given below of the agreed calculated extension - Longitudinal Tendons for Segments - If the measured extensions are not within the specified tolerance then the Contractor shall submit to the Engineer his method of rectifying the discrepancy - When the prestressing force has been applied to the satisfaction of the Engineer, the tendons shall be anchored The force exerted by the tensioning apparatus shall then be decreased gradually and steadily so as to avoid shock to the tendon or anchorage - Full records shall be kept of all tensioning operations including measured extensions, pressure gauge or load cell readings and drawin at anchorage Copies of records shall be supplied to the Engineer within 24 hours of each tensioning operation - Unless otherwise agreed by the Engineer, tendons shall not be cut less than days after stressing 5% Sequences for casting concrete - After installation of the bottom formwork, gate gantry for lifting beams - Checking correction of installation, cleaning the bottom formwork - Installation of reinforcing steel, ducts and anchorage - Installation of the side formwork, place the concrete - Placing concrete for beams by agitators combined crane - Curing concrete - Removal of the side formwork, threading prestressed strands, stressing strand tendons, pumping grout into the ducts - Move the beams to storage yard - And continue casting other beams as the above sequences end formwork and preparing to 17/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE 18/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE CHAPTER III: INSTALLATION OF I BEAMS FOR TRA NOC, SANG TRANG 1, SANG TRANG BRIDGES I Construction Requirements - - Prior to the erection of the beams the Contractor shall survey the positions of the supporting columns and agree the positions, both horizontal and vertical, of the supports with the Engineer - Complete details covering the equipment to be used to handle beams and to incorporate them into the structure together with a step by step erection procedure shall be submitted to the Engineer for his approval - The order of erection of the beams and the casting of top slabs shall be such that the eccentricity of loading on the supporting columns and the foundations is minimized - Transportation and erection of beams shall be carried out in such a manner that there is minimal interference to road traffic - When beams are being placed in position they shall be braced against overturning before being released by the crane or other lifting devices - Beams shall be prevented from moving laterally during the placing of the insitu concrete - Before conducting the launching and erection of beams, the Contractor shall submit a full method statement for his proposed methods for lifting and placing beams in their permanent position The method statement shall be submitted to the Engineer for his approval in writing prior to construction - Launching and erecting girders done by suitable mechanical equipment, which adapts the weight and size of the beams - Erection of beams is done by cranes The Contrator will use 02 cranes 80T and 01 crane 63T for installation of beams - Road for beam transport must be guaranteed flatness, stability to withstand the pulling force of the beam, the weights of the beam together with the auxiliary equipment in construction After construction of the transport road, it will be inspected by the Engineer in writing prior to transporting beams - Before erecting beams, the Contractor shall perform the following requirements: + Carry out trial erection to observe If it is safe for workers and equipments, the official erection will be conducted + Inspection of the bearing pads + In the process of moving beams the stable bracing must be taken to ensure no overturning and upturning during movement After completion of beam installation, the completion of inspection sheets, records for quality shall be made then move to next items 19/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE II Inspection of quality - Inspect the flatness of the geometric dimensions, cracks, warping, camber of the beams prior to construction - After installation is complete, the following criteria should be checked: III + The alternation between the center lines of the beams on the piers and abutments + Tolerance of vertical alignment of beams + Difference of heights between surfaces of the beams on a pier + Difference of heights between surface of the beams on the adjacent piers The sequence construction of the superstructure for Tra Noc, Sang Trang 1, Sang Trang bridges Corresponds to the construction of each branches (left and right side), suppersutructure construction will follow order of substructure - - Step 1: Prepare casting yard: Construction of service road for lifting beam Casting yard and storage yard will be located in Km6 +000 of NH91 Casting bed will be casted in-situ combined with shaped steel Steel Formwork will be fabricated in workshop and in-situ Before using, inspection will be carried out Storage yard is located next to the casting bed to facilitate movement of beam; Beams are chocked on the Yard as calculation diagram Step 2: Cast beams for the entire package Check the casting bed, installing bottom formwork on the Bed; Installation of reinforcing steel, anchors, ducts; Installation of side formwork, end formworks; Inspection and acceptance of formwork and reinforcing steel; Pour concrete: Produce concrete by batching plant; Cast concrete by cranes and mixer truck; Vibrate concrete by form vibrator and Concrete Poker Vibrator ; Cure of concrete, remove formwork; Thread and and stress PC strand tendon when concrete gets enough strength for tensioning; Grouting of Ducts and Sheathing Move beam to storage yarad by Gate Gantry together with manpower 20/ 31 PHUONG THANH TRANCONSIN ... Quantities of I 33 m beams: - Tra Noc bridge: 70 beams Sang Trang 2: 43 beams All I33m beams will be casted in Casting Yard at Km6+000 The Contractor will organize 04 casting bed for I 33 m beam... documents for labels, codes and categories 5/ 31 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE 3. 3 3. 4 3. 5 II - Steel must be separated in each... takes 09 samples, 03 samples tested after 72 hours (3 days), 03 following samples is tested after days, 03 remaing samples to determine the 28-day strength The testing sample is cylinder 150x300