土木工程外文翻譯----建筑類型和設計

1、濰坊學院本科畢業(yè)論文一、原文building types and designA building is closely bound up with people，for it provides with the necessary space to work and live in . As classified by their use ,buildings are mainly of two types :industrial buildings and civil buildings .industrial buildings are used by various factories

2、 or industrial production while civil buildings are those that are used by people for dwelling ,employment ,education and other social activities . Industrial buildings are factory buildings that are available for processing and manufacturing of various kinds ,in such fields as the mining industry ,

3、the metallurgical industry ,machine building ,the chemical industry and the textile industry . factory buildings can be classified into two types single-story ones and multi-story ones .the construction of industrial buildings is the same as that of civil buildings .however ,industrial and civil bui

4、ldings differ in the materials used and in the way they are used . Civil buildings are divided into two broad categories: residential buildings and public buildings .residential buildings should suit family life .each flat should consist of at least three necessary rooms : a living room ,a kitchen a

5、nd a toilet .public buildings can be used in politics ,cultural activities ,administration work and other services ,such as schools, office buildings, parks ,hospitals ,shops ,stations ,theatres ,gymnasiums ,hotels ,exhibition halls ,bath pools ,and so on .all of them have different functions ,which

6、 in turn require different design types as well. Housing is the living quarters for human beings .the basic function of housing is to provide shelter from the elements ,but people today require much more that of their housing .a family moving into a new neighborhood will to know if the available hou

7、sing meets its standards of safety ,health ,and comfort .a family will also ask how near the housing is to grain shops ,food markets ,schools ,stores ,the library ,a movie theater ,and the community center . In the mid-1960s a most important value in housing was sufficient space both inside and out

8、.a majority of families preferred single-family homes on about half an acre of land ,which would provide space for spare-time activities .in highly industrialized countries ,many families preferred to live as far out as possible from the center of a metropolitan area ,even if the wage earners had to

9、 travel some distance to their work .quite a large number of families preferred country housing to suburban housing because their chief aim was to get far away from noise ,crowding ,and confusion .the accessibility of public transportation had ceased to be a decisive factor in housing because most w

10、orkers drove their cars to work .people were chiefly interested in the arrangement and size of rooms and the number of bedrooms . Before any of the building can begin ,plans have to be drawn to show what the building will be like ,the exact place in which it is to go and how everything is to be done

11、. An important point in building design is the layout of rooms ,which should provide the greatest possible convenience in relation to the purposes for which they are intended .in a dwelling house ,the layout may be considered under three categories : “day”, “night” ,and “services” .attention must be

12、 paid to the provision of easy communication between these areas .the “day “rooms generally include a dining-room ,sitting-room and kitchen ,but other rooms ,such as a study ,may be added ,and there may be a hall .the living-room ,which is generally the largest ,often serves as a dining-room ,too ,o

13、r the kitchen may have a dining alcove .the “night “rooms consist of the bedrooms .the “services “comprise the kitchen ,bathrooms ,larder ,and water-closets .the kitchen and larder connect the services with the day rooms . It is also essential to consider the question of outlook from the various roo

14、ms ,and those most in use should preferably face south as possible .it is ,however ,often very difficult to meet the optimum requirements ,both on account of the surroundings and the location of the roads .in resolving these complex problems ,it is also necessary to follow the local town-planning re

15、gulations which are concerned with public amenities ,density of population ,height of buildings ,proportion of green space to dwellings ,building lines ,the general appearance of new properties in relation to the neighbourhood ,and so on . There is little standardization in industrial buildings alth

16、ough such buildings still need to comply with local town-planning regulations .the modern trend is towards light ,airy factory buildings .generally of reinforced concrete or metal construction ,a factory can be given a “shed ”type ridge roof ,incorporating windows facing north so as to give evenly d

17、istributed natural lighting without sun-glare .Assessment of natural radioactivity levels and radiation hazards due to cement industry AbstractThe cement industry is considered as one of the basic industries that plays an important role in the national economy of developing countries. Activity conce

18、ntrations of 226Ra, 232Th and 40K in Assiut cement and other local cement types from different Egyptian factories has been measured by using -ray spectrometry. From the measured -ray spectra, specific activities were determined. The measured activity concentrations for these natural radionuclides we

19、re compared with the reported data for other countries. The average values obtained for 226Ra, 232Th and 40K activity concentration in different types of cement are lower than the corresponding global values reported in UNSCEAR publications. The manufacturing operation reduces the radiation hazard p

20、arameters. Cement does not pose a significant radiological hazard when used for construction of buildings.1. IntroductionThe need for cement is so great. That it considered a basic industry. Workers exposed to cement or its raw materials for a long time especially in mines and at manufacturing sites

21、 as well as people, that spend about 80% of their time inside offices and homes (Mollah et al., 1986; Paredes et al., 1987) result in exposure to cement or its raw materials being necessary reality so we should know the radioactivity for cement and its raw material. There are many types of cements a

22、ccording to the chemical composition and hydraulic properties for each one. Portland cement is the most prevalent one. The contents of 226Ra, 232Th and 40K in raw and processed materials can vary considerably depending on their geological source and geochemical characteristics. Thus, the knowledge o

23、f radioactivity in these materials is important to estimate the radiological hazards on human health. The radiological impact from the natural radioactivity is due to radiation exposure of the body by gamma-rays and irradiation of lung tissues from inhalation of radon and its progeny (Papastefanou e

24、t al., 1988). From the natural risk point of view, it is necessary to know the dose limits of public exposure and to measure the natural environmental radiation level provided by ground, air, water, foods, building interiors, etc., to estimate human exposure to natural radiation sources (UNSCEAR, 19

25、88). Low level gamma-ray spectrometry is suitable for both qualitative and quantitative determinations of gamma-ray-emitting nuclides in the environment (IAEA, 1989).The concentration of radio-elements in building materials and its components are important in assessing population exposures, as most

26、individuals spend 80% of their time indoors. The average indoor absorbed dose rate in air from terrestrial sources of radioactivity is estimated to be 70 nGy h?1. Indoors elevated external dose rates may arise from high activities of radionuclides in building materials (Zikovsky and Kennedy, 1992).

27、Great attention has been paid to determining radionuclide concentrations in building materials in many countries (Amrani and Tahtat, 2001; Rizzo et al., 2001; Kumar et al., 2003; Tzortzis et al., 2003). But information about the radioactivity of these materials in Egypt is limited. Knowledge of the

28、occurrance and concentration of natural radioactivity in such important materials is essential for checking its quality in general and knowing its effect on the environment surrounding the cement producing factories in particular.Because of the global demand for cement as a building material, the pr

29、esent study aims to: (1) Assess natural radioactivity (226Ra, 232Th and 40K) in raw and final products used in the Assiut cement factory and other local factories in Egypt. (2) Calculate the radiological parameters (radium equivalent activity Raeq, level index Ir, external hazard index Hex and absor

30、bed dose rate) which is related to the external -dose rate.The results of concentration levels and radiation equivalent activities are compared with similar studies carried out in other countries.2. Experimental technique2.1. Sampling and sample preparationFifty seven samples of raw materials and fi

31、nal products used in the Assiut cement factories were collected for investigation. Twenty five samples of raw materials were taken from (Limestone, Clay, Slag, Iron oxide, gypsum) which are all the raw material used in cement industry, 20 samples of final products were taken from Assiut cement (Port

32、land, El-Mohands, White, and Sulphate resistant cement (S.R.C). For comparison with products from other factories, 8 samples were taken from the ordinary Portland cement from (Helwan, Qena, El-kawmya, Torra) and 4 samples were taken of white cement (Sinai and Helwan). Each sample, about 1-kg in weig

33、ht was washed in distilled water and dried in an oven at about 110 C to ensure that moisture is completely removed, The samples were crushed, homogenized, and sieved through a 200 mesh, which is the optimum size to be enriched in heavy minerals. Weighted samples were placed in a polyethylene beaker,

34、 of 350-cm3 volume. The beakers were completely sealed for 4 weeks to reach secular equilibrium where the rate of decay of the radon daughters becomes equal to that of the parent. This step is necessary to ensure that radon gas is confined within the volume and the daughters will also remain in the

35、sample.2.2. Instrumentation and calibrationActivity measurements were performed by gamma ray spectrometry, employing a 33scintillation detector. The hermetically sealed assembly with a NaI(Tl) crystal is coupled to a PC-MCA (Canberra Accuspes). Resolution 7.5% specified at the 662 keV peak of 137Cs.

36、 To reduce gamma ray background a cylindrical lead shield (100 mm thick) with a fixed bottom and movable cover shielded the detector. The lead shield contained an inner concentric cylinder of copper (0.3 mm thick) to absorb lead X-rays. In order to determine the background distribution in the enviro

37、nment around the detector, an empty sealed beaker was counted in the same manner and in the same geometry as the samples. The measurement time of activity or background was 43 200 s. The background spectra were used to correct the net peak area of gamma rays of measured isotopes. A dedicated softwar

38、e program (Genie 2000 from Canberra) analyzed each measured -ray spectrum.3. ConclusionThe natural radionuclides 226Ra, 232Th and 40K were measured for raw materials and final products used in the Assiut cement factory in Upper Egypt and compared with the results in other countries. The activity con

39、centration of 40K is lower than all corresponding values in other countries. The activity concentration of 226Ra and 232Th for all measured samples of Portland cement are comparable with the corresponding values of other countries. The obtained results show that the averages of radiation hazard para

40、meters for Assiut cement factory are lower than the acceptable level 370 Bq kg?1 for radium equivalent Raeq, 1 for level index Ir, the external hazard index Hex 1 and 59 (nGy h?1) for absorbed dose rate. The manufacturing operation reduces the radiation hazard parameters. So cement products do not p

41、ose a significant radiological hazard when used for building construction. The radioactivity in raw materials and final products of cement varies from one country to another and also within the same type of material from different locations. The results may be important from the point of view of sel

42、ecting suitable materials for use in cement manufacture. It is important to point out that these values are not the representative values for the countries mentioned but for the regions from where the samples were collected.Prestressed ConcreteConcrete is strong in compression , but weak in tesion :

43、 its tensile strengh varies from 8 to 14 percent of its compressive strength . Due to such a low tensile capacity , flexural cracks develop at early stages of loading . In order to reduce or prevent such cracks from developing , a concentric or eccentric force is imposed in the longitudinal directio

44、n of the structural element . This force prevents the cracks from developing by eliminating or considerably reducing the tensile stresses at the critical midspan and support sections at service load, thereby raising the bending , shear , and torsional capacities of the sections . The sections are th

45、en able to behave elastically , and almost the full capacity of the concrete in compression can be efficiently utilized across the entire depth of the concrete sections when all loads act on the structure .Such an imposed longitudinal force is called a prestressing force , i.e. , a compressive force

46、 that prestresses the sections along the span of the structual element prior to the application of the transverse gravity dead and live loads or transient horizontal live loads . The type of prestressing force involved , together with its magnitude , are determined mainly on the basis of the type of

47、 system to be constructed and the span length and slenderness desired . Since the prestressing force is applied longitudinally along or parallel to the axis of the member , the prestressing principle involved is commonly known as linear prestressing .Tension caused by the load will first have to can

48、cel the compression induced by the prestressing before it can crack the concrete. Figure 4.39a shows a reinforced concrete simple-span beam cracked under applied load. At a relative low load, the tensile stress in the concrete at the bottom of the beam will reach the tensile strength of the concrete

49、 , and cracks will form. Because no restraint is provided against upward extension of cracks, the beam will collapse. Figure 4.39b shows the same unloaded beams with prestressing forces applied by stressing high strength tendons. The force, applied with eccentricity relative to the concrete centroid

50、, will produce a longitudinal compressive stress distribution varying linearly from zero at the top surface to a maximum of concrete stress, = , at the bottom, where is the distance from the concrete centroid to the bottom beam, and is the moment of the inertia of the cross-section, is the depth of

51、the beam. An upward camber is then created. Figure 4.39c shows the prestressed beams after loads have been applied. The loads cause the beam to deflect down, creating tensile stresses in the bottom of the beam. The tension from the loading is compensated by compression induced by the prestressing. T

52、ension is eliminated under the combination of the two and tension cracks are prevented. Also, construction materials (concrete and steel) are used more efficiently. Circular prestressing , used in liquid containmeng tanks , pipes , and pressure reactor vessels , essentially follows the same basic pr

53、inciples as does linear prestressing . The circumferential hoop . or “hugging” stress on the cylindrical or spherical structure , neutralizes the tensile stresses at the outer fibers of the curvilinear surface caused by the internal contained pressure . From the preceding discussion , it is plain th

54、at permanent stresses in the prestressed structural member are created before the full dead and live loads are applied in order to eliminate or considerably reduce the net tensile stresses caused by these loads . With reinforced concrete , it is assumed that the tensile strength of the concrete is n

55、egligible and disregarded . This is because the tensile forces resulting from the bending moments are resisted by the bond created in the reinforcement process . Cracking and deflection are therefore essentially irrecoverable in reinforced concrete once the member has reached its limit state at serv

56、ice load .The reinforcement in the reinforced concrete member does not exert any force of its own on the member , contrary to the action of prestressing steel . The steel required to produce the prestressing force in the prestressed member actively preloads the member , permitting a relatively high

57、controlled recovery of cracking and deflection . Once the flexural tensile strength of the concrete is exceeded , the prestressed member starts to act like a reinforced concrete element .Prestressed members are shallower in depth than their reinforced concrete counterparts for the same span and load

58、ing conditions . In general , the depth of a prestressed concrete member is usually about 65 to 80 percent of the depth of the equivalent reinforced concrete member . Hence , the prestressed member requires less concrete , and about 20 to 35 percent of the amount of reinforcement. Unfortunately , th

59、is saving in material weight is balanced by the higher cost of the higher quality materials needed in prestressing . Also, regardless of the system used , prestressing operations themselves result in an added cost : formwork is more complex ，since the geometry of prestressed sections is usually composed of flanged sections with thin webs .In spite of these additional costs, if a large enough number of precast units are manufactured, the difference between at least the initi