建筑毕业设计外文翻译及译文

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1、Development and analysis of the large-span FRPwoven web structureABSTRACT: An innovative large-span structural system, namely the FRP woven web structure (FRPWWS), is introduced in this paper. In an FRPWWS, the high-strength FRP strips are “woven” like bamboo strips in a Chinese bamboo mat to form a

2、 plane web. The outer edge of the web is anchored on an outer ring beam, and an inner ring beam is provided to anchor the FRP strips at the center of the web. The stiffness of the web to resist various loads is derived from the initial prestressing during the “weaving” stage and the additional tensi

3、oning as a result of the out-of-plane movement of the inner ring beam. As a result of the high strength-to weight ratio of FRP, this new structural form offers an attractive option for the construction of spatial structures with spans longer than are possible with conventional structural materials.

4、In this paper, the basic layout and construction procedure for a simple FRPWWS is first presented. Three basic weaving patterns are next explained. Several variations of the basic structural system are also proposed. A simple mechanical model is presented for the deformation of individual FRP strips

5、. Results from a finite element analysis of an example structure are also given. The results of these analyses confirm the feasibility of the FRPWWS.1 INTRODUCTION FRP is a new kind of structural material, whose use in civil engineering has been actively explored in recent years. Due to its favorabl

6、e properties like corrosion resistance, high strength, low weight, good fatigue performance, and low maintenance cost, it is considered to be an ideal material for constructing long-span structures in the new century. However, its mechanical properties are distinctly different from those of traditio

7、nal structural materials in some aspects, such as its anisotropy. Due to the unique properties of FRP, it is necessary to explore new forms of large-span structures for its efficient use and for achieving spans larger than are possible with traditional materials. For example, Maeda et al. (2002) hav

8、e conceived a 5000 meter-span suspension bridge using FRP. The FRP woven web structure, a new large-span structural system, is presented in this paper. This new system represents an attempt aimed at the efficient utilization of the unique characteristics of FRP in a large-span roof. In an FRPWWS, th

9、e high strength FRP strips are woven like bamboo strips in a Chinese bamboo mat to form a plane web. The outer edge of the web is anchored on an outer ring beam, and an inner ring beam is provided to anchor the FRP strips at the center of the web. A small-scale model of a simple FRPWWS is shown in F

10、igure 1. The FRP strips are initially prestressed to a limited extent to keep them straight during “weaving”. Then, the FRP web is tensioned by a displacement of the inner ring beam in the out-of plane direction, which is effected either by a set of prestressed tendons or by suspending a heavy mass

11、from the inner ring beam. As a result, a tensioned FRP web, whose geometric stiffness is able to resist a variety of loads, forms a large-span roof system with the two rings. The FRPWWS resembles the cable net structure and the cable-membrane structure: their members are flexible; and the geometric

12、stiffness resulting from tension is utilized to resist loads. However, the FRPWWS has its unique advantages: (1) the FRP strips are ideal for super large-span structures due to their low self-weight and their superior material properties in the lengthwise direction, which are efficiently utilized, w

13、hile the weakness of inferior properties in the transverse directions is not exposed; (2) significant damping can be expected to arise from friction at joints between FRP strips, which can enhance the resistance of the structure to wind and earthquake loads; (3) the regular weaving pattern leads to

14、an aesthetically pleasing surface; and (4) the corrosion resistance of FRP and the ease of installation because of its lightweight translate into low maintenance costs.In this paper, the basic layout and construction procedure for a simple FRPWWS system is presented in detail. The weaving patterns i

15、n plane aresummarized into three types. Some spatial FRPWWS forms for practical applications are also proposed. A simple mechanical model for individual FRP strips in the web is presented. Results from the finite element analysis of a simple FRPWWS are also described.2 LAYOUT OF A SIMPLE FRPWWSA sim

16、ple FRP woven web structure is composed of a FRP woven web, an outer ring beam and an inner ring beam for anchorage, and an additional weight or a set of prestressed tendons, as shown in Figure 1. The web is woven with FRP strips, and CFRP strips or other high-performance hybrid FRP strips are sugge

17、sted. CFRP strips, which have been widely used to strengthen concrete structures in recent years, are manufactured by pultrusion in general, with a fiber volume ratio of about 65%. The properties of two representative products made in China and Switzerland respectively are listed in Table 1.The stri

18、ps can be curved and circumvoluted due to their small thickness. A typical CFRP strip with properties similar to those shown in Table 1 is able to resist a tensile force of 400kN or more, while the weight of a 300m long strip is less than 70kg. In comparison, the self weight of a 300m long high stre

19、ngth steel cable which can resist the same load is more than 500kg. The strips are arranged into a plane surface of a suitable pattern by some pre-defined rules. In the simplest weaving pattern, each strip passes over one crossing strip and under the next to form a web like a woven fabric. A part of

20、 such web is shown in Figure 2 (Pong et al. 2004). In a more general case, the number of strips meeting at a joint and the angles between these strips are the basic parameters of a weaving pattern: two strips at 90 to each other are shown in Fig. 3(a), three strips at 60 shown in Fig. 3(b), and four

21、 strips at 45 shown in Fig. 3(c). At the joints, strips can be fully inter-connected by adhesive bonding after complete shape formation or left unbonded so that sliding between strips is allowed. In the latter case, the static friction between strips can contribute to the stiffness under static load

22、ing while the sliding friction can consume the kinetic energy of the structure under dynamic loading.3 CONSTRUCTION OF SIMPLE FRPWWSFollowing the five construction steps as shown in Figure 4, a simplest FRPWWS can be completed. First, the outer and inner ring beams on temporary supports are construc

23、ted. In general, the outer ring beam is in compression and the inner one is in tension when the web is in place. The outer ring beam is made of reinforced concrete while the inner ring beam is made of steel. The web which is woven with FRP strips is next fixed onto the ring beams with hinge joints a

24、nd provided with some initial tension to form a plane surface. A tentative hinge joint scheme between the strip and the ring beam is shown in Figure 5, where the strip is tightly clamped between two stiff plates. The weaving of the strips should follow the rules of a specified weaving pattern which

25、should have been designed by the structural engineer and the architect together. Weaving can be carried out easily due to the light weight and small thickness of FRP strips. The temporary supports to the inner ring beam are now withdrawn and the inner ring beam moves in the out-of-plane direction by

26、 its self-weight plus an additional weight where necessary. This out-of-plane displacement of the inner ring beam can also be effected by a set of high strength tendons. The installation of these prestressed tendons completes the construction process. According to force decomposition, a small out-of

27、-plane force causes a large in-plane component and enables the web to be tensioned, leading to a web of sufficient stiffness to resist various loads.4 MORE COMPLEX FORMS OF THE FRPWWS4.1 Basic plane weaving patternsThe FRP web is the main component in the FRPWWS system. Various weaving patterns can

28、be adopted for the initial plane web, which will result in different mechanical behavior. They may be classified into the following three types: tiled patterns, radiated patterns and polygonal patterns. A web weaving pattern that is independent of the boundaries is referred to as a tiled pattern as

29、shown in Figure 6.The radiated pattern and the polygonal pattern are both made up of a number of repeated sets, each of which is composed of a number of line segments. Some examples of these two types are shown in Figures 7 and 8 respectively. Any pattern of these two types has its own defining rule

30、s. In practice, these three types of weaving patterns may be combined where appropriate in an FRPWWS system.4.2 Spatially curved outer ring beamIn a real structure, a spatially-curved outer ring beam may be adopted to achieve a more appealing building shape. If the outer edge of the FRP web is ancho

31、red onto such a ring beam, the strips can form a smooth curved surface in space, as shown in Figure 9. The shape is that of a piece of stressed cloth placed on the curved beam. Because the web is composed of individual strips, it offers great flexibility in forming a curved surface with good mechani

32、cal behavior.4.3 Double web systemThe load carrying capacity of an FRPWWS is mainly provided by its geometric stiffness derived from the tensile forces in the FRP strips. The strips are prestressed in two steps: initial prestressing in plane before anchorage to the ring beams and second stage prestr

33、essing through the out-of-plane movement of the inner ring beam. The former is applied to each strip one by one, to achieve a plane web surface and to control the total displacement. The latter is applied to shape the web and to achieve a predefined stress level, which can be realized in many differ

34、ent ways, including the use of prestressed tendons as mentioned earlier, uplifting with a stay column and a hung heavy weight on the inner ring beam, which may be retractable roof equipment. An alternative to the above approaches is to form two webs, whose inner ring beams are then pulled together o

35、r pushed apart to induce tensile forces in the strips. Such a double-web structure is illustrated in Figure 10. Figure 10(a) shows a saucer-shaped FRPWWS achieved by pushing apart the two inner ring beams, while Figure 10(b) shows a butterfly shaped FRPWWS achieved by pulling together the two ring b

36、eams.4.4 FRPWWS with multiple ring beamsThere are only two ring beams in a simple FRPWWS. If more ring beams are used as shown in Figure 11, a large web will be divided into several shorter spans. The difficulty of construction and design will decrease as the length of continuous FRP strips becomes

37、smaller. If a double-web system is provided with many ring beams, a folded-web system results (Figure 12). The above are just some possible variations of the basic FRPWWS. In practical applications, many other forms/shapes can be explored. The FRPWWS may also be combined with other structural system

38、s to become hybrid structural systems.5 ANALYSIS OF A SIMPLE FRPWWS5.1 Individual FRP stripEach FRP strip in the web is mainly subject to tension if interaction between strips at joints is ignored. A pair of strips at 180o apart in a simple web can be modeled as two strips whose ends are connected t

39、o the outer beam and the inner ring beam respectively, as shown in Figure 13. The outer beam is regarded as a fixed point while the inner ring beam is treated as a rigid body. There are three states for the strips: initial prestressed state, out-of-plane tensioned state and service loading state. It

40、 is assumed that the cross-sectional area of the strip is A, the elastic modulus is E, the difference between the radii of the inner and the outer ring beams is L, and the self weight and flexural stiffness of the FRP strip are neglected because they are very small. In the first state as shown in Fi

41、gure 13(a), a horizontal initial prestressing force H0 is applied to the end of the strip. Then the strain of the strip is (1)The initial length of the strip is (2)In the second state as shown in Figure 13(b), two vertical loads V are applied on the inner ring beam to move it down to tension the str

42、ips. The tensile force in the strip is T1, whose horizontal component is H1, and the displacement of the inner ring beam is 1.Based on equilibrium consideration, there is (3)If the strain of the strips at this time is 1, then (4) (5)From the geometric relationship, there is (6)Combining these equati

43、ons, T1, 1, 1 can be found.In the third state, the strips are required to support a service load q(x) which is symmetrically placed with respect to the centre of the inner ring beam. The reaction at the fixed end can be decomposed into the horizontal force H2 and the vertical force R.The total defle

44、ction of a point at a distance x from the fixed point is denoted by z(x), the deflection due to the service load is denoted by w(x), and the total displacement of the inner beam is denoted by 2. Hen, (7)The deflected shape is governed by the following cable equation (Sheen 1997): (8)If q(x) is a uni

45、form load, the deflection curve can be found easily by double integration to be: (9)and Equation (7) becomesR=qL+V (10)The slopes at the strip ends are (11) (12)Based on deformation compatibility, the total length change of each strip in the second stage is given by (13)but the second stage elongati

46、on found from strains is (14)Thus, H2 and 2 can be found from Equations 10-14.As an example, a pair of strips for a model FRPWWS as shown in Figure 13 is considered, where L=80m and the properties of the strips are the same as those of product 2 in Table 1. In the first stage, an initial stress of 5

47、00MPa is induced in the strips, then 0=0.0024, L0=79.81m, and H0=84kN. In the second stage, an out-of-plane force V=30kN is applied. As a result, 1=7.14m, 1=0.0064, H1=225.3kN and the stress in the strips is 1344MPa. Finally, a uniform load q=0.5kN/m is applied on the strips, and consequently 2=10.2

48、7m, H2=389.5kN, and the maximum stress in the strips is 2352MPa and occurs near the outer fixed end.From this simple analysis, the key parameters for an FRPWWS can be identified. These include the initial control stress or the prestressing force H0, the out-of-plane force V or the deflection of the

49、inner beam 1. They control the deformation of the web under loading and the stress level in the FRP strips.5.2 A simple FRPWWSA simple FRPWWS as shown in Figure 14 was analyzed by the finite element method using the finite element package ANSYS (2000). It has a 150m span, and the radius of the inner

50、 ring is 30m. Product 2 listed in the Table 1 is employed in this structure, which is assumed to have a design value of 2000 Map for the tensile strength. Only the radiated pattern is adopted. There are 360 repeated sets altogether, each of which is composed of three strips. Thus, there are 1,080 FR

51、P strips in the structure. The geometric nonlinearity from large deformation was considered in the finite element analysis, while interaction between strips was neglected. The self weight of the FRP web is ignored as it is only 177kN which is much smaller the total load acting on the structure.The s

52、tress level in the initial prestressed web is controlled to be no more than 210MPa, while that after the downward movement of the inner ring beam no more than 1000 Map. From the finite element analysis, under a vertical force of 14,400 ken for the second stage operation, the inner ring beam moves do

53、wn by 5.08 m and the maximum stress in the strips reaches 995MPa. The construction of the FRPWWS is now complete. As the weight of each strip in this FRPWWS is less than 18kg, which can be carried by an adult, the construction of this structure is expected to be easy. The total weight of the strips

54、in the FRPWWS is estimated to be about 19,440 kg.The completed FRPWWS was next subject to a factored uniform load of 1.8kN/m2 over the entire area enclosed by the outer ring beam, which is intended to include the self-weight of the roofing material, wind loading and snow loading. Under this loading,

55、 the maximum deflection increase is 1.22m and the total maximum stress in the FRP strips is 1542MPa, which is about 85.7% of the design stress. The structure is thus strong enough to resist this loading.6 CONCLUSIONSThe FRP woven web structure (FRPWWS), which represents a new application of FRP in l

56、ong-span structures, has been presented in this paper. The key aspects of this new system are listed below.I. The FRP woven web, the ring beams and the out-of-plane tension system are the basic components of the FRPWWS.ii. There are five construction steps for a simple FRPWWS as illustrated in Figur

57、e 4.iii. The plane weaving patterns can be summarized into three types: tiled patterns, radiated patterns and polygonal patterns.iv. Following the same basic principle, many different forms can be constructed. The paper has discussed several such possibilities, including the use of a spatially curve

58、d outer ring beam, the double-web system and systems with multiple ring beams.v. An FRPWWS experiences three distinct stress states: the initial prestressed state, the out-of-plane tensioned state and the service loading state, all of which should be considered in design.7 ACKNOWLEDGEMENTSThe author

59、s are grateful to the Natural Science Foundation of China for their support to the research presented here through a national key project on the application of FRP composites in civil engineering in China (Project No. 50238030) and through the Joint Research Fund for Hong Kong and Macao Young Schola

60、rs (Project No. 50329802).REFERENCESANSYS, Inc. 2000. ANSYS Users Manual.Maeda, K., Ikeda, T., Nakamura, H., Maharishi, S. 2002. Feasibility of ultra long-span suspension bridges made of all plastics. Proceedings of IABSE Symposium (CD-ROM), Melbourne, Australia, 2002.Pong, X.Q., Cao, J., Chen, J.,

61、Due, P., Lustier, D.S., Liu, L. 2004. Experimental and numerical analysis on normalization of picture frame tests for composite materials. Composites Science and Technology 64(1):11-21.Shen S.Z., CSU, C.B., Zhao, C. 1997. Cable-suspended structure design. Beijing: China Building Industry Press. (In

62、Chinese)大跨度FRP网架结构的展望和分析摘要：本文将会介绍一种新的大跨度结构，FRP织网结构。在一个FRPWWS结构中，高强度的FRP材料条像中国竹席中的竹片一样被编织在一起形成一个平面网，这个网状结构的外围锚固在一个圈形的梁上，结构的中心处还有一个用于锚固织网的内圈梁。织网结构靠编织生产时的初步预施加应力和内圈梁面外运动引起的附加张力调整来抵抗遇到的各类荷载。由于FRP材料的具有较高的材料-重量比，这种全新的结构形式为一些大跨度的空间建设提供了一种具有吸引力的选择方案，该跨度长于用常规结构材料建筑的跨度。在本文中，首先介绍了简单的FRPWWS结构的基本布局和施工步骤，接着阐明了三种基

63、本的织造结构，同时也提出了此类结构方式的几种变化。文中介绍了一个简单的力学模型用于单个的FRP条力学变形，也给出了一个实例结构的有限元分析的过程。1引言FRP是一种新型的结构材料，近年来在土木工程中的研究很活跃。由于他具有一些良好的性能，如抗腐蚀，重量轻，强度高，抗疲劳性好以及维修费用低，它被认为是在新世纪建造大跨度结构的理想建材，但是它在某些方面的机械性能与那些传统的结构材料还是有明显的区别，譬如它的各项异性现象。由于FRP材料的独特性，为了FRP材料的有效使用以及获得传统建材所不能及的跨度，有必要研究新型的大跨度结构。Maeda et al.(2002)就设想了用FRP材料建造跨度5000

64、米的悬索桥。本文提出了FRP织网结构结构，一种全新的大跨度结构形式。这种新的结构形式旨在试图在一个大跨度的屋顶中有效利用FRP材料的性能。在FRPWWS结构中，高强度FRP编制像中国传统竹席中的竹片一样被编织成一个平面网状结构。这个网状结构的外沿锚固在外圈梁上，结构的中心处还有一个较小的内圈梁用于锚固织带。图1所示既是一个小型FRPWWS结构模型。为保证进行“编织”时FRP材料条的平直，首先要对FRP编织条施加一定程度的预应力。然后，通过内圈梁的面外移动来拉动FRP织网，施加预应力的过程可以通过预应力筋拉伸或在内圈梁设一定的重力来达成。 因此，受拉的FRP网形成了一个带有两个圈梁的大跨屋面，该FRP网的集合刚度能抵抗各种荷载。FRPWWS结构类似于索网或索网膜结构：他们的构成部分是灵活多变的；并且靠拉伸引起的几何刚度来抵抗各种荷载。然而，FRPWWS结构有其独特的优点：（1）FRP材料自重低且纵向上优越的材料性能被有效利用，而横向上的弱点却没有暴露出来，因此在超大跨度的结构中FRP系统是理想的；（2）FRP编条的交汇处会产生巨大的阻尼，从而加强结构抗风抗震能力；（3）有规则