In order to ensure the bridge structure under temperature changes, live loads, concrete shrinkage and creep affected by static deformation trying to type freely, we need to make between the two ends of the beam between the beam end and Back and the deck Set horizontal joints (known as Deformation). There are expansion joints constructed with simple complex, depending on the size and the amount of deformation bridge live load wheel weight varies, its role is not only to ensure the beam deformation physical freedom, but also to make the vehicle can smoothly through the expansion joints and prevent rain, penetrate dirt and other rubbish blocking. For urban bridges should be constructed so that the seam to reduce noise when the vehicle passed. Bridge expansion joints problem is still in the exploratory study, the flatness of its highway lane greater impact. In order to improve the flatness of the road and bridge connecting at, on the one hand should increase the length of the bridge linking the hole in order to reduce the number of joints, the other must continue to improve type, material, and design and construction quality expansion joints. Currently, research joints problems, explore and improve the bridge has caused concern of experts and scholars at home and abroad, the paper intends to make the following brief questions on joints. Bridge expansion joints produced mainly jumping stairs expansion joint device or damaged caused by the occurrence of disease, especially the expansion of road and bridge engineering stage, more and more heavy vehicles repeatedly rolling road, bridge, causing bridge expansion joints severely damaged, how to extend the life of bridge expansion joints? A choice: bridge expansion joints are part of the bridge structure, if not properly designed, installed poor quality, lack of scientific and not timely maintenance, the bridge will form the majority of the steps in the bridge expansion joints, bridge directly affect the quality of service; design Engineers in the design process to focus only on the expansion joints retractable bridge calculation, and thus make the selection, but the performance is often not fully understood telescopic device, ignoring the relevant technical requirements; another deck joints continuous deformation false slit width and depth set not standardized, not unified, which to varying degrees, affect the normal operation of two continuous seam Ann: Ann refers to the construction and installation of a bridge expansion joints, is the key to move the bridge expansion joints, is the focus of measures in order to catch part of the construction team opened to traffic, construction workers this way deliberately, hard living and easy negligent, careless construction, do not follow the installation procedures and operational requirements of the construction; telescopic device installed after the concrete has not reached the intensity of traffic ahead of the open, resulting in produce concrete anchoring transition period early damage, leading to decline in the operating environment of three joints: the conservation of the current expansion joints in order to reduce a large number of continuous beam or continuous deck, the deck would need to set up a continuous seam continuous present, continuous seam setup is not perfect , resulting in a continuous seam damage, arising deck jumping; bridges in the operation process, improper maintenance, bridge deck joints and uneven aging bridges heavy traffic during the operation, fast speed, heavy-duty vehicles will wait damage caused by the bridge, seriously affecting traffic safety. Bridge expansion joints need water stop, two-component polysulfide sealant, foam board three things, expansion joints from the inside out: Sealing (sealing) --- foam board (filled, waterproof) --- Seal cream (caulk, impervious) relatively narrow joints, foam board placed in the middle, to reduce the loss of sealant; ① closed-cell polyethylene foam board, also known as foam board, EPS board is made may contain volatile liquid blowing agent polystyrene beads by heating white object after an advance in the mold thermoforming, which has a fine closed cell structure mainly used in building walls, roof insulation, composite board insulation, refrigerator, air conditioning, vehicle , insulation, floor heating, decorating carvings and other uses of the ship is very broad. Its function is to fill the gap unfavorable configuration is complex and construction in order to play a role in sealing ② bridge expansion joints in the use of rubber sealing strip expansive water tightness effectively prevent rainwater seepage and protect the bridge expansion joints with the normal function of the road and avoid damage. ③ polysulfide sealant has excellent oil, water, acid, impact resistance and other characteristics; at (-60 ℃ -110 ℃) temperature range of long-term use, low gentle song is good; a low modulus, high elongation long, non-sagging bridge expansion joint sealing material welding precautions ① bridge expansion joints transported to the scene, you have to put segmented steel welded together, the preferred test it fully telescopic device flatness, straight degrees, elevation and other projects, ② qualified before welding welding electrodes using high quality, one by welding, soldering first top surface, a bottom surface and then welded to the anchor shaped steel beams reinforced with embedded steel on both sides simultaneously weld, the best time to weld. When the subject difficult to weld the first side to be installed to achieve the desired temperature, and then the other side of all weld; welded steel top surface to be polished ③ welding process can not be applied on any steel welded to prevent deformation of steel. There may hinder reinforced cut off all, especially the large amount of displacement telescopic steel ⑤ device control box at the entire construction process should not allow vehicles from passing ⑥ telescopic device to prevent damage during construction when the notched edge ④ lifting position, Otherwise, re-cut seams, joints to ensure neat cut, straight; diameter across the plate to Φ14, Φ16 is appropriate, too Rules strong enough, too thick affect the strength of the concrete. ⑦ If good waterproof tape factory installed, you must first set up a template, then welded anchor tendons 

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