The durability of engineering structure
The durability of engineering structure is linked with the service life. It is the capacity that structure keeps the normal function during the time of using the kind of function includes the stability of the structure and the serviceability of the structures and what’ more it can be used widely
1 the present condition of the durability of engineering structure
Most engineering structure is made of concrete. The durability of engineering structure is the universal problem of disturbing engineering structure and foundation of designing currently. Not only in China .but didn't yet cause the our country government supervisor section sum enough value of the large design and the construction section up to now.
For long time, the people have been think the concrete and should be a very enduring material. Developed country did not discover gradually to set up at first until 70's last phase of infrastructure engineering appeared to damage early under some environments. American many concretes of city infrastructure engineering and port engineering, harbor engineering set up the post - anti to two,30 years even appear the degradation in shorter period; According to a material estimate of the American civil engineering meeting of 1998, they need to have 1.3 US$s to handle the existent question of American local infrastructure engineering, the concrete bridge facing slab a term of the only repair and the replacement public highway bridge need 80,000,000,000 beautiful non -, but the present federal government only have USD 50-6,000,000,000 for this appropriation annually. There is another stuff point out, the United States cause the steel-bar corrosion to need the limit to carry the passing public highway bridge to have already had this environment because of the divide ice salt bridge of 1/4.The developed country threw in a great deal of research budget for the concrete structure freeze thaw durability the union adopts to reply the performance actively, such as in order to deal with the divide ice salt corrosion and frost thawing to injure, the public highway bridge of Canadian Ontario the minimum thickness of the concrete protecting layer of the concrete reinforcing rode increased the 4 cms,6 cams gradually from the 2.5 cams of the 50's until after 80's of 7 cams, and the concrete strength most the lower class also increases the later C40 from the C25 of the 50's, the deck slab concrete never requests the in addition to lead the gas trunk agent, not establish the water proof layer to arrive and must lead gas trunk and need to establish the deluxe waterproof cut an, coating and lead into the hoop oxygen to draw the concrete reinforcing rode of film. But the our country suffer the public highway bridge of the salt jelly erosion area to design the aspect in the freeze thaw durability up to now still without explicit request, to the concrete protecting layer in accordance with the request of the strength only is the 2.5 cams and C25s, with the over - speak of the level of 50's of Canada. The domestic press an of this kind of standard design, because the salt freezes the erosion, now already have to the division tore down the rebuilding.
The our country construction department in 80's of a the term survey express, local and most objects of industrial building need the overhaul namely after use 25-30 years, being placed in the harsh environment under of service life of building only 15-20 years. Public build the usage environment of the sum public building opposite better, can maintain 50 years above generally, but the ante solarium, rain hood of the outdoors etc. the service life of the open-air structural member usually has 30-40 years only. Bridge, the harbor work etc. the freeze thaw durability question of the infrastructure engineering is more serious, because of the concrete protecting layer of the concrete reinforcing rode over thin and the density difference, many engineering’s set up several years of post - appear the steel-bar corrosion, concrete shake. About decade of general usage of the sea port quay wall because of the concrete shake and peel off, the demand overhaul. The city interchange of the area of Jingling because the winter spreads the divide ice salt and frost actions, use more than ten appear the question after year, have of can not be unlimited to carry, overhaul or tore down. The salt freezes to also result in hurt to the concrete pavement, the northeast area a high standard highway, classified highway of summer beam is only through a winter the shiner product denudation. The our country railway tunnel makes the lining material with the concrete of C15 of the low strength, density and the anti- seep difference, don't bear the subsoil water and the locomotive waste gas erosion, shake and the influent seepage severities; To the tube progress sampling survey enunciation that several roads play govern, have 50.4% lea kingly, among them 1/3 the oozes are seriously, and cause rail etc. the fittings rust eclipse and the electrical power haulage lot electric leakage, effect the normal running, but railway tunnel design specification promulgate in 1999 not yet the energy adopts the appropriate policy to the freeze thaw durability question of the tube, adding fiber etc. of chemistry in the concrete such as the lowest strength order sum of the appropriate exaltation concrete.
The seriousness and urgencies of the freeze thaw durability question lay in us many just the engineering that construct not yet absorbs local great deal of greatly aggrieved precept of international sum, return along old road. Some northern cities set up lately of interchange and the express highway bridge, still did not construct to wait prevention and cure frost thawing and the comprehensive performance of the salt injuries that the aspect adopts the necessity in the characteristic of materials and structure. even the large engineering, such as the shot sea lotus that 2000 throw in the running, sails across ocean the great bridge, its corpus structure splashes the thick protecting layer thickness of the concrete of C30 and 3-4 cases that the ward still adopts the anti to bear the wet alternative erosion of the sea water shank in the wave.
The has the expert estimate, the high tide of the our country" big shank” infrastructure engineering construction can also continue 20 years, because of neglecting the freeze thaw durability, greet we will still have" overhaul" for 20 years of high tide, this high tide possibility need not for a long time waste arrival, it will double in amount in at the beginning investment for these engineering constructions to construct.
1) measure the standard with the single strength fiducially mark conduct and actions customarily because of the mass examination of the concrete, cause the cement industry pursued to the incapability of the cement strength, make the cement fineness increase, the speedy and strong mineral proportion of ingredient exaltation, these are all disadvantageous in the freeze thaw durability of the concrete. our country to the examination of the cement mass in strength last as long as beg the minimum of being no lower than the specified to admit the value, and the abroad then still request to be no higher than the tallest value of the specified at the same time, if the strength exceeded to also is think hors concur, this kind of uniformity that requests to still be advantageous to the cement product mass.
2) Unwell region of the engineering construction unit speeds the construction degree of progress, particularly is the government administration leadership to the out of character intervention of the work project. the freeze thaw durability mass of the concrete particularly need to have the enough construction the curing age takes into the assurance, the concept of the harmful life health of premature is applicable to the concrete equally. so-called and several months that local medium apply to publicize greatly ups fix a boulevard of simmer beam, set up a great bridge, or shroud an engineering of high building and rob the work gift engineering, may be from now on to destine to spend the die young engineering of the overhaul of progress of more coffered very much. Complete the agreement in advance specified construction the age want to be fine money abroad, because mean that the engineering mass encounters the possibility for injure.
3) the environment is continuously worsen, such as the waste gas, acid rain, the acid rain time area concentration diagram of the our country has already exceeded 30% of the national territory.
At present the urgently the job that need to be carry on draws up the technique regulation of the infrastructure engineering freeze thaw durability designs, such as bridge, tube and the harbor work...etc. as soon as possible, revising to add the current specification in to the request of the structure freeze thaw durability. Need to be explicit first is various design of infrastructure engineering job length of life, must have the request and justifications of the service life in the document of design of the important engineering. current at numerous engineering’s that set ups are on the freeze thaw durability of so still along the old road walk, very important reason is the engineering design start construction the technical personnel is in there is no the new reference that be able to follow on freeze thaw durability. More seriously of being current specification of some ruling, one is harmful to the freeze thaw durability. for raising the concrete freeze thaw durability, in the concrete reasonable usage fly ash, the mine dirt...etc. the mineral addition is an important technique way, the specification that abroad have even rule and must join the fly ash in bridge wait concrete structure etc. addition, but the railroad concrete bridge of the our country, the construction specification of tube still forbids the usage in the plaintext. in addition, the engineering technique the field still exists the long-term some viewpoints of out of date of the formation, to the enduring function of the concrete of betterment result in resistance drag. for example, the worry will effect the concrete strength but don't wish to use to lead the gas trunk agent, but lead the gas trunk originally should be the betterment the concrete freeze thaw durability and the routine way of the workability; again such as, hope the enlargement cement dosage to guarantee the concrete strength, but the possibly low dosage of cement should be important path that raises the concrete anti- breaking joint sum to endure the function originally.
It is freeze thaw durability request that revise the specification, the harbor work concrete structure rot proof eclipse technical specification that Ministry of Transportation & Communications promulgate in 2001 already for other soils set up the profession of engineering rises to arrive to compare good of demonstration action. we want to according to the stuff that have already at home and abroad and experience on the other hand, weaving to write as soon as possible a the design construction technique document that correspond needs by meet an emergency, the research item that on the other hand then want to arrange the system, the enlargement freeze thaw durability the support strength of the research work; the freeze thaw durability of the concrete structure is current international up the course of structural engineering is most important to follow to study the realm before of a, but the our country is in this aspect fall behind very. The freeze thaw durability research of the concrete cans not get away from the particular conditions, such as original material and environment...etc., the characteristics that need to consider the our country, is a complete dependence of incapability the abroad research result of.
The values the freeze thaw durability of the concrete structure also is can keep on the development of demand. produce the original material of cement, sand, stone...etc. that concrete need to all need a great deal of depletion national territory resources union rupture vegetation and stream bed, the carbon dioxide that cement produces to exhaust hazes already had mankind's activity to exhaust the overall measurement of 1/5-1/6, but the second that the carbon dioxide quantity that our country exhaust has already resided the world. our country now annually produce more than 500,000,000 tons cement, with it concomitant is the year consume 20 much hundred million squares of sandstone, continuously for a long time hence solid hard for after. Lengthen the structure service life to mean to economize the material, but the concrete of the lasting generally should be a higher concrete of the dosage of cement lower sum mineral addition (the industry scrap) dosage again, so the concrete of the lasting is adapting the demand of the environmental protection. International top to the design job length of life of the civil engineering’s, such as bridge and tube...etc. much for 100 years, have such as England is 120 years. In consideration of the huge economic loss and waste of resources that the freeze thaw durability shortage result in, international up have the request to put forward the bridge in the urban environment to should have for 150 years at least the lowest job length of life of these engineering’s trend of the further extension, if in recent years.
2. The normal detection and maintenances of the structural engineering step
The structure freeze thaw durability and the concept of the service life, can't partition with the detection, the maintenance sum repair of the usage step, to be placed in the bad environment of the open air sum under of infrastructure engineering to say particularly and thus. for the sake of the assurance structure stability and freeze thaw durability, some engineering’s are in set up become post - of usage process, should carry on the periodical detection sum maintenance. the our country contain structural engineering of design specification and construction specification, but have no how the specification that use. some engineering’s tumble down the accident, for example the south thumb latch great bridge occurrence floor deck of the Szechwan proper guest collapses to fall the accident recently, be because the hanger rod between deck structure and main arch is public at connect an occurrence rust eclipse, if have the periodical detection request, such accident avoids very probably. some nation's damages toward structure may cause the building and bridges, tubes of the public safety etc. public works, constraint the specified must periodically examine; even is a building of prismatic glass curtain wall and exposed wall face brick act’s build the assembly unit, subassembly, harm easily after sinking into because of it with, have already also periodic allied constraint the request for examine. our country because of the opposite discrepancy of character that the construction management level and accident operate the personnel, not enough sound of quality control and the quality assurance systems, the structure safety and the constitution level of the freeze thaw durability for specification is again opposite and lower, have already set up in the engineering to usually exist the more to suffer from, so even have the necessity from the legal system the certain soil sets up the normal usage sum of the engineering request of the periodical detection. for the safe mass that the soil sets up the structural engineering, although the government already have made the responsibility unit sum of the design and construction is personal need as to it's" be responsible for life long" of specified, this kind of requests to carry out to lack the maneuverability. Want to reduce safe quality accident of structure to lowest extent; return should regard prevention as principle, passing the routine detection to discover the question in time.
There is a great deal of soil in the present domestic set up the engineering because of following the weathering age to need to be make a diagnosis and give treatment, also have the illegal engineering that mass set up already to need to be evaluate, even have many engineering’s occurrence disease to harm to need to examine a patient the sum strengthening, everyplace has already mowed flow out not a few be engaged in the soil sets up the diagnosis of engineering and manages with the strengthening of troops, also the booming development becomes a kind of trends of newly arisen profession. Appear the question and disease to harm hereafter manage again surely important, but we should more emphasize the prevention. For at the service soil sets up the engineering of the detections sum valuation, to build up the homologous laws and standard, to have the employee of the registrations sums are from the industry mechanism of the natural intelligences attestation system, in managing the system give the specification.
It is from the nation to the public works construct of investment sum to the engineering design of request to see, need to have the engineering the whole useful life namely life cycle cost the justification of the expenditure. only notice the engineering item construction of once invest the expenditure, the few consideration engineering needed the normal maintenance and the long-term expenses of the repair after set up, not only may injure the normal usage function of sum of service life of engineering, but also economy up calculate the general account would be very not worth the cost. at developed country, because of lately set up the engineering little, used for to maintain of expenses usually more main, the soil of 1978 of England set up the maintenance cost to rise till 1965 of 3.700%, the soil that the maintenance cost of 1980 had that year set up the expenses total expenditure of 2/3. our country though developing country, the present is build many new buildings, but in the past set up of a great deal of engineering already or super - speedy weathering.40% bridge age of public highway bridge of domestic already greater than, larger than 25 years, plus to enter for 90's later traffic volume fierce super -, overload seriously, former design standard again low, the road, bridge maintains the question to full the sailing over. Because of the curing maintains the expenses to can not get the assurance, making engineering safe the suffer from union at hereafter need to expend more expenses of overhaul. At the soil sets up the engineering of investment up, hope department concerned energy enlargement have already set up the expenses that engineering maintain.
It is the case for accelerate the road bridge etc. The public works construction, the company a of the national present encouragement investment combines the joint to compensate with the certain term, such as 30 years of the management income conduct and actions, if the counterweight wants that the soil set up the engineering contain laws that must carry on the periodical detection and valuations, can guarantee these engineering’s at certain term after return the national superintendence sum management of good function, is 100 years of bridge for the design job length of life, can also use 70 years normally at least, but be unlikely after 30 years expire what the nation receive is already a broken-down engineering.
The effect of the technology code and management
The science and technology forum sets up the fixing, positioning of the structural engineering technical specification and acts and manages to also carry on the discussion and put forward some viewpoints to the soil this time.
It is effect by the planned economy system for long time, we usually treat technical specification as the logarithm of time fitting method log, having the concrete specified of the specification is similar to request to equal the law ruling to treat. technical specification or procedures, request with various technique regulation, technique, work logarithm of time fitting method log, guidebook etc. the technique document is all the technique standard, oneself not the law action, should only everyone of engineering (owner, design, construction enterprise) the approbation conduct and actions design and the reference of the construction union in the agreement of ground wok up, the reference that then can be the law arbitration. Progress the technique question legalization union compulsory execution, disadvantage in the technique the sum creation of exertive, become shirk responsibility on the contrary and easily of borrow the port. certainly, the government section is from the national sum the public and whole benefits set out, need to put forward to the design construction that the soil sets up the engineering in principle in the grave nesses, such as safety and environmental protection...etc. must satisfy of minimum request to combine the establishment to correspond of laws, but the laws does not need to provide generally how the concrete technique path and device that attain these requests, the latter is the mission of the technique standard. the government also can approve or grant the some and important technical specification with the principle or among them some contents usage.
The soil sets up the engineering to have the strong character, needing the technical personnel of engineering to resolve the design and the construction problems to concrete characteristics. so the specification is the technique standard proper emphasize that it guides sex and antis to are a compulsive. if the law ruling that ruling of specification sees the general meaning of conduct and actions, probably the bonding brick design constructer of active create the new technical application of sex union obstruction.. the our country soil set up the engineering compares with abroad on the structural design of the biggest margin lie in the scheme with the technical innovation, this with over-emphasize the specification before of the trend anti that law position thus becomes so-called" the structural design is a specification to apply the computation" without connection. the technical specification of the our country in weaving to write the style the trend that have already also copied the law, rarely mention the user demand to notice the place of some shortage that the specification may exist or allow and encourage the user and can open up another the diameter on some problems. if have already fallen behind the out of date in design under constructional to replace specification even harmful technique specified, then just like in break the law the behavior. Contrary, as long as resist change the specification, even have an accident past, don't take the law responsibility. thus at objective up lower to request to request with job to the business skill of the technical personnel of engineering, disadvantage in raise the our country building enterprise and the character of the employees and participate the international competition of the aftertime. for removing these negative influences and eradicating completely the empty son progress of drill the ruling of specification to cheat on labor and material, should have the necessity establishment such consensus and make a specified, then obey the ruling of specification not to mean and then can dismiss the law responsibility. Foreign some specifications are to rule thus of.
The attempt to be continuously compulsive of intensify the technical specification to resolve to forbid the not only engineering accident often, don't is problem-solving valid path. Present, the relevant supervisor section will build parts of ruling extracts within the structural design specifications to come, listing as to constraint sex ruling definitely, ruling the design that each design unit complete at the same time, other businesses that beard through department concerned or its authorizations appoint design the reviewing of the unit, but the main contents of the reviewing lies in the request that the contrast specification constraints sex ruling, its mission has already is similar to in enforce the law; This kind of way of doing whether the advisability still need to be study. The our country soil sets up the multifarious reason of the engineering accident, mainly lying in the bad management, managing the corruption on the link especially; Is a construction to operate personnel's character the next in order low, the again hard short date solve; Over-emphasize the position and actions of the specification, can not build up with the complete and standard system of the kit of specification, lack the more detailed concrete technique documents, such as guidebook and the work logarithm of time fitting method log...etc. for example, can use to guide the sum specification design and the each concrete link of the constructions, also have the certain relation. See from the design angle, appear the lord of accident to if it were not for because of have no specified that constraints sex ruling according to the specification, but scheme mistake or neglect the principal design condition; Also have some engineering’s to then cause the failure because of past design standard over low, the freeze thaw durability shortage, lack the routine detection that should have again in use process. In fact, to attain the request that the design specification constraints the ruling easy, invite the professional reviewing for this has no occasion for. The important engineering design should rule to invite the professional unit to examine completely; its main also should in the structure scheme, the structure device and the computation analysis of in principle. From the national specification of the structural design in the compulsive sex ruling of the extract is unavoidably fragmented and disorganized, separately the specified of the ruling also the concrete characteristics of uncertain in keeping with some engineering’s of some area sums, result in bother on the contrary.
The compulsive within the technique standard is more many, also meaning the government department concerned on the concrete technique question the responsibility that demand undertake is more heavy, but these originally shouldn't be the job of the government section. The request in the specification is the minimum request, establishing the level in the safety up, the government need to be interfering of also should be lowest request that guarantees the public safety. For the seismic design, earthquakeresistance design that the soil sets up the structure, the government department concerned still rules any section sum up to now personal can not raise the anti- to shake at will of establish and defend standard.(set up the anti- No.586 document)In fact, such as establish the anti- earthquake of the merchandise house to defend the earthquake intensity to raise one kilowatt hour, the anti- earthquake capacity can raise about 100%, but the building of the increase build the price very limited, possible to be only in numerous cities and the dweller used for indoor repair one of several bat batches of the expenses. This specified just like of the government in the building that the restrictive dweller can purchase the anti- earthquake safe mass standard minimum only, if the occurrence quake result in injure, how does the department concerned explain?
The specification etc. The system of superintendence of the technique standard needs the betterment. Found a nation, the government section is responsible of the series tube and specify the relevant enterprise unit to undertake the each specification plait to write the way of doing that the sum revises the job respectively to have already canned adapt the current situation less and less, some can not get the assurance on the budget and man powers, the mean time is basically there is no specialized personnel collect understand that the question in the usage of specification union modifies to add the ruling of specification in time; Face the new industrial art of new structural style, new material sum, the dated ruling of the specification not only become the new technical resistance drag of generalization, but also have to be misemploy or the blindness set use but result in the safety misadventure of engineering mass.
The specification that relevant soil of developed country of the sets up the structural engineering and with each kind of technique of its kit standard poly - from profession association or professional academic association establishment and superintendence, the specification turns over the new period short, anti image we want long 10 hearses above. the academic association of the our country and association repeats the constitution, divide the work not clear, and still be depend on in up to now some a government section, the action that rise the not official spokesperson of section of working talent of government basically and only, is a rich apart from the independent sum vigorous and sound mechanism to still differ very far, how develop these mechanisms in the technique standard weave write the sum superintendence of action also is deserve inquiry into of a question. Suggestion along with reform thorough, restructure the relevant academic association, association of merger, intensifies its working talent, and gradually become the technique the corpus that standard draws up the superintendence.
