土木工程外文翻譯---抗震鋼筋混凝土結(jié)構(gòu)設(shè)計原則

1、<p><b>　　附　錄 </b></p><p>　　Seismology Civil Engineering</p><p>　　SEISMIC RESISTANT REINFORCED CONCRETE STRUCTURES-DESIGN PRINCIPLES</p><p>　　SUMMARY:Earthquakes cau

2、se considerable economic losses.It is possible to minimize the economic loses by proper seismic design.In this paper basic principles for seismic design are summarized.There are three basic requirements to be satisfied;(

3、a)strength,(b)ductility and(c)stiffness.In the paper these are briefly discussed.</p><p>　　In the second part of the paper the author summarizes his views on the damages observed in the past earthquakes.He c

4、oncludes that most of the damages have been due to,(a)bad configuration,(b)inadequate detailing and(c)inadequate supervision.In the paper these are discussed,pointing out the common mistakes made and damages observed as

5、a result of these mistakes.In the last part of the paper some simple recommendations are made for producing seismic resistant reinforced concrete structures,emphasi</p><p>　　Key Words:Seismic resistance,rein

6、forced concrete.</p><p>　　1.INTRODUCTION</p><p>　　Every year more than 300 000 earthquakes occur on the earth.Many of these are of small intensity and do not cause any damage to our structures.H

7、owever,earthquakes of larger intensity in the vicinity of populated areas cause considerable damage and loss of life.It is estimated that on the average 15000 people have been killed each year throughout the world becaus

8、e of earthquakes.</p><p>　　Since ancient times mankind has sought ways and means of minimizing the damage caused by earthquakes.The great masters of the art of building have been able to build structures whi

9、ch have withstood many severe earthquakes for centuries.Magnificent mosques and bridges in the Middle East built by our ancestors are still in service,These masters did not know seismic analysis,but were able to evaluate

10、 past experience with their excellent engineering intuition and judgement.Mosques,bridges and school</p><p>　　Today we have great advantages as compared to our ancestors.We have more experience,we have highl

11、y developed analytical tools and considerable experimental data.It should also be noted that computers enable us to consider more variables and several alternatives in the analysis.</p><p>　　The main objecti

12、ve of this paper is to lay down some basic principles for producing earthquake resistant reinforced concrete structures.These are simple principles and easy to apply.They have been developed in the light of analytical an

13、d experimental research done and on observations made from past earthquakes.</p><p>　　2.BASIC PHILOSOPHY AND REQUIREMENTS</p><p>　　Design principles cannot be laid down unless there is a well de

14、fined design philosophy.The design philosophy generally accepted is summarized below:</p><p>　　-Buildings should suffer no structural damage in minor, frequent earthquakes. Normally there should be no nonstr

15、uctural damage either.</p><p>　　- Buildings should suffer none of minor structural damage (repairable) in occasional moderate earthquakes.</p><p>　　- Buildings should not collapse in rarely occu

16、rring major earthquakes. During such earthquakes structures are not expected to remain in the elastic range. Yielding of reinforcing stell weill lead to plastic hinges at critical sections.</p><p>　　The gene

17、ral design philosophy will not have much practical use unless design requirements are developed in parallel with this philosophy.The author believes that the design requirements can be summarized in three groups.</p&g

18、t;<p>　　a.Strength requirements</p><p>　　b.Ductility requirements</p><p>　　c.Stiffness requirements(or drift control).</p><p>　　These three requirements will be briefly discu

19、ssed in the following paragraphs.</p><p>　　2.1.Strength Requirements</p><p>　　Members in the structure should have adequate strength to carry the design loads safely.Since the designers are well

20、 acquainted with this requirement,it will not be discussed in detail.However,it should be pointed out that the designer should avoid brittle type of failure,by making a capacity design(1).The basic principles in capacity

21、 design are illustrated for a beam in Figure 1.If the design shear is computed by placing the ultimate moment capacities at each end of the beam,the designer can ma</p><p>　　2.2.Ductility Requirements</p&

22、gt;<p>　　In general it is not economical to design R/C structures to remain elastic during a major earthquake.It has been demonstrated that structures designed for horizontal loads recommended in the codes can onl

23、y survive strong earthquakes if they can have the ability to dissipate considerable amount of energy.The energy dissipation is provided mainly by large rotations at plastic hinges.The energy dissipation by inelastic defo

24、rmations requires the members of the structure and their connections to poss</p><p>　　Adequate ductility can be accomplished by specifying minimum requirements and by proper detailing(2).</p><p>

25、;　　2.3.Stiffness Requirements</p><p>　　In designing a building for gravity loads,the designer should consider serviceability in addition to ultimate strength.In seismic design,drift limitations imposed might

26、 be considered to be some kind of a serviceability requirement.However,the drift limitation in seismic design is more important than the serviceability requirement.</p><p>　　The limiting drift is usually exp

27、ressed as the ratio of the relative storey displacement to the storey height(interstorey drift).Excessive interstorey drift leads to considerable damage in nonstructural elements.In many cases the cost of replacing or re

28、pairing of such elements is very high.Excessive interstorey drift can also lead to very large second order moments(P-effect)which can endanger the safety and stability of the structure.Therefore interstorey drift control

29、 is considered to be one of</p><p>　　3.LESSONS LEARNED FROM PAST EARTHQUAKES</p><p>　　Our knowledge in seismic design has developed has developed as a result of analytical and experimental resea

30、rch and experience gained from past earthquakes.The author believes that lessons learned from past earthquakes have been the most important source among all others,because earthquakes perform the most realistic laborator

31、y tests on the buildings.</p><p>　　The author has reevaluated the damages observed in earthquakes during the past 30 years in Turkey.This reevaluation has revealed that more than 90%of the damages can be att

32、ributed to one of the following causes or combinations of these:</p><p>　　a.Mistakes made in choosing the building configuration(general configuration or the structural system chosen).</p><p>　　

33、b.Inadequate detaling and proportioning or errors made in detailing.</p><p>　　c.Poor construction quality caused by inadequate supervision.</p><p>　　It is interesting to note that causes of dama

34、ge grouped into the above three categories seem to apply to earthquake damages observed in other countries also.These three causes will be discussed briefly in the paragraphs to follow.</p><p>　　3.1.Building

35、 Configuration</p><p>　　Seismic resistance should be initiated at the architectural design stage.If the general configuration chosen by the architect is wrong,it is very difficult and expensive for the struc

36、tural engineer to make the building seismic resistant.As a general principle the floor plan should be as symmetrical as possible.The length of wings(T,L,.cross shaped buildings)causing re-entrant corners should not be la

37、rge.If the length of the wings is not short,then these should be separated from the main building</p><p>　　As far as the structural system is concerned,one can set out some basic rules for better seismic res

38、istance.Before setting out these rules,it would be appropriate to remind the engineers that nonstructural infill walls will influence the frame behaviour significantly unless separated from the frame.</p><p>

39、;　　Sudden changes in stiffness along the height of the building should be avoided.If the stiffness of one storey is significantly smaller than the others(soft storey),premature failure can occur due to excessive lateral

40、displacement at this floor level.As shown in Figure 2,changes in the storey stiffness can be caused not only by structural elements,but also by nonstructural elements such as infill walls.</p><p>　　Two adjac

41、ent buildings should be separated from each other by an adequate distance in order to avoid the damage caused by pounding or reciprocal hammering of the buildings.</p><p>　　The vertical load carrying element

42、s in a floor should be so proportioned and arranged that the center of mass and center of resistance should nearly coincide.If these two centers are away from each other,the resulting eccentricity can cause severe floor

43、torsion,increasing the shear forces at the boundary elements considerably.Torsion is not only created by structural elements(Figure 3b)but can also be created by infill walls unless separated from the frame,Figure 3a.<

44、;/p><p>　　The maximum shear force which be acting on a column can be found by adding the moment capacities(ultimate moments)at each end of the column and dividing by the column length Figure 4.This simply means

45、 that,if the length of the column is/5,then the column will carry five times as much shear.For this reason,short columns should be avoided whenever it is possible,because of the Figure 3.danger of shear failure.As illust

46、rated in Figure 4,short columns are created by either structural or nonstructura</p><p>　　Structures with flexible floor members(flat plates or joist system with shallow beams)should either have rigid column

47、s or shear walls(or cross-bracing)to prevent excessive drift.If the vertical load carrying members are not rigid enough,very high second order moments can result as shown in Figure 5.In 1967 Adapazari and 1985 Mexico ear

48、thquakes numerous failures have been observed in buildings with flexible floors and slender columns.</p><p>　　For a more detail discussion on configuration,the reader is directed to Reference 2.</p>&

49、lt;p>　　3.2.Proportioning and Detailing</p><p>　　The dimensions of structural members not only influence the strength,but also the overall stiffnes of the structure.In the light of experience gained from t

50、he past earthquakes,the author believes that the ratio of the sum of the cross-sectional areas of vertical load carrying members to the floor area is an important parameter in seismic resistance.This ratio will be called

51、 the"Density Ratio".The author has studied the variation of this ratio in the monumental historical buildings in Istanbul,wh</p><p>　　Mosque is shown in Figure 6.The author would like to point out

52、the symmetry in the arrangement of load carrying members.In Süleymaniye the density ratio was about 0.24.</p><p>　　Another investigation made on modern reinforced concrete buildings built in seismic are

53、as in Turkey reveal that the average density ratio is less than 0.01.The author finds the ratio rather low and suggests that it should be about 0.015-0.0020.</p><p>　　In the city of Vina del Mar,Chile the av

54、erage density ratio in reinforced concrete buildings(4 to 23 stories)is quite high,0.06(3).This seems to be one of the reasons why relatively small damage occurred during the 1985 Chile earthquake,which created quite a s

55、evere ground motion.</p><p>　　It should be pointed out that although density ratio is a very important parameter for lateral stiffness,the relative stiffness of floor members have also a significant influenc

56、e on the stiffness.</p><p>　　Ductility required for energy dissipation during an earthquake is closely related to detailing.A well designed R/C structure can suffer considerable damage if it is not properly

57、detailed.</p><p>　　Detailing is an art which cannot be realized unless the seismic behaviour of reinforced concrete is well understood.The basic principle in detailing is to provide the necessary strength an

58、d ductility at critical sections and joints.In cutting the bars and in making lapped splices,adequate anchorage length should be provided.The critical regions where plastic hinging is expected to occur should be well con

59、fined by closely spaced hoops.Our experience in Turkey shows that inadequate detailing playe</p><p>　　Basic rules for detailing of beams,columns and structural walls are summarized in Figures 7,8 and 9.</

60、p><p>　　3.3.Construction</p><p>　　The earthquake will be resisted by the structure which is actually built and not by the structure shown on the design drawings.No matter how good the design method

61、s used are,it is not possible to produce a seismic resistant building unless the structure is constructed in accordance with the design project under proper supervision.In most of the developing countries emphasis is on

62、the design stage;quality control and supervision are usually looked down upon and ignored by the engineer.</p><p>　　The engineer should realize that the important requirements for seismic resistance,i.e.the

63、strength,ductility and stiffness depend on the actual dimensions,material qualities and reinforcement details accomplished on the site.Poor supervision results in poor material quality and errors in the placement of the

64、reinforcing steel.Our experience in Turkey shows that inadequate supervision has been the most important cause of structure damage during past earthquakes.</p><p>　　In the light of these discussions one can

65、conclude that,for better seismic resistance,the first step should be in the direction of correcting the mistakes made in the past.If configuration,detailing and construction supervision cannot be improved,well written co

66、des and sophisticated methods of analyses will not be able to prevent damage and failures in future earthquakes.</p><p>　　4 RECOMMENDATIONS FOR DESIGN</p><p>　　The main objective of this section

67、 is to specify some simple rules for the design of ordinary reinforced concrete structures.By ordinary,the author means regular structures</p><p>　　up to say ten stories.</p><p>　　4.1.Summary of

68、 Facts</p><p>　　Before stating the design rules,it would be useful to state some basic facts about the seismic action and seismic resistance of reinforced concrete structures.</p><p>　　-The char

69、acteristics of the ground motion expected cannot be fully defined.</p><p>　　-The structure cannot remain elastic when subjected to a strong ground motion.Yielding will occur at different locations and most o

70、f the energy will be dissipated at these sections.</p><p>　　-Response of the structure depends not only on the ground motion,but also on the dynamic characteristics of the structure,such as mass,stiffness an

71、d damping.For reinforced concrete structures it is very difficult to estimate the stiffness and damping,because of cracking and time dependent deformations which have taken place prior to the earthquake.</p><p

72、>　　-Nonstructural elements influence the behaivour.</p><p>　　-In order to analyze a building,first a simple physical model is created by making many simplifying assumptions.The analysis made is for this m

73、odel and not for the real building.The assumptions made in creating this model introduce errors.</p><p>　　-Important dynamic characteristic such as mass,stiffness and damping depend on the actual dimensions

74、and material strengths obtained during construction.These can be quite different from the ones assumed at the design stage.</p><p>　　In the light of these facts,one can easily see that there are many uncerta

75、inties involved in the seismic design of reinforced concrete buildings.The engineer should be</p><p>　　well aware of these facts and should not rely entirely on the numbers he has obtained from analyses.More

76、 sophisticated and more complicated methods of analyses can easily carry the engineer away from the actual behaviour and make him a slave of numbers.Usually simple methods supported by sound judgement based on behaviour

77、will result in as satisfactory seismic design.</p><p>　　4.2.A simple Approach</p><p>　　Seismic resistance can be accomplished by following the basic steps given below:</p><p>　　a.Ch

78、oosing a good configuration</p><p>　　b.Making a satisfactory analysis(Static or dynamic)</p><p>　　c.Proportioning and detailing the members properly.</p><p>　　d.Constructing the bui

79、lding in accordance with the design project,under good supervision.</p><p>　　The author believes that for ordinary residential or office buildings up to say ten stories,seismic resistance can be obtained to

80、a great extent by following some simple rules.The rules given below are being used by a municipality in Turkey as a guide to designers and for checking the designs submitted to this municipality.The first rule concerns t

81、he density ratio mentioned previously.For residential and office buildings up to ten stories,the summation of the cross-sectional areas of vertical lo</p><p>　　Av 0.020Ap(1)</p><p>　　Av-summatio

82、n cross-sectional areas of all vertical</p><p>　　structural members at the floor(m2)</p><p>　　Ap-plan area at that floor(m2)</p><p>　　In addition to this rule,the cross-sectional ar

83、ea of each individual column should satisfy the following condition:</p><p>　　Ac 0.0015At(n)(2)</p><p>　　However the minimum column dimensions cannot be less than 25x25 cm.</p><p>　

84、　Ac-cross-sectional area of the column(m2)</p><p>　　At-tributory area of the column(m2)</p><p>　　n-number of stories above</p><p>　　The second set of rules are about minimum require

85、ments and detailing.These are summarized in Figures 7,8 and 9 for beams,columns and structural walls.</p><p>　　In addition to these two sets of rules,the designer should choose a reasonable configuration and

86、 proper supervision should be provided at the construction stage.If these simple rules are followed and if the requirements are satisfied,most probably adequate seismic resistance will be obtained for the building classe

87、s specified,even if a lateral load analysis is not performed.</p><p>　　5.CONCLUSIONS</p><p>　　The response of reinforced concrete buildings under seismic action depends not only on the nature of

88、 the ground motion,but also on the dynamic characteristics of the structure.Due to uncrtainties involved in estimating the nature of the ground motion and the structural characteristics,only approximate results can be ex

89、pected from analyses.The numbers obtained from analyses should be filtered by making use of past experience and judgement.Sound judgement can only be based on a firm knowledge abou</p><p>　　REFERENCES</p&

90、gt;<p>　　1.Sözen MA:"Toward a Behaviour Based Design of R/C Frames to Resist Earhquakes",9.Technical Conference of Turkish Society of Civil Engineers.VI.1,pp.1-44,Ankara,1978.</p><p>　　

91、2.Ersoy U:"Basic Principles for the Design of Seismic Resistant R/C Structures",Workshop on Seismic Design,RSS, Amman,Jordan,Nov.1987.</p><p>　　3.Riddell R,Wood SL,De La Llera JC:"The 1985 Chi

92、le Earthquake",Civil Engineering Studies,Structural Research Series No.534,UILU-ENG.87-2005,University of Illinois,Urbana,April 1987.</p><p><b>　　外文資料翻譯</b></p><p><b>　　土木

93、工程地震學(xué)</b></p><p>　　抗震鋼筋混凝土結(jié)構(gòu)設(shè)計原則</p><p>　　摘 要：地震造成相當(dāng)多的經(jīng)濟(jì)損失。通過適當(dāng)?shù)目拐鹪O(shè)計將經(jīng)濟(jì)減到最少是可能的。本論文中概述了地震設(shè)計的基本原則。有三個基本要求需要滿足：(a)強(qiáng)度，(b)延性和(c)剛度。本論文對這些進(jìn)行了簡短的討論。</p><p>　　在本論文的第二部份中，作者觀察過去地震中所造成

94、的破壞并概述了自己的看法。 他總結(jié)出大部份的損害可以歸結(jié)于：(a)不規(guī)則的外形，(b)不充分的細(xì)節(jié)設(shè)計，(c)不充分的監(jiān)督。本論文都對這些進(jìn)行了討論，作者指出那種常見的錯誤和觀察到的破壞就是由這些錯誤引起的。</p><p>　　在論文的最后一個部份中作者為鋼筋混凝土結(jié)構(gòu)的抗震設(shè)計給出一些簡單的建議， 并強(qiáng)調(diào)結(jié)構(gòu)的細(xì)節(jié)設(shè)計使其成比例。</p><p>　　關(guān)鍵字：抗震，鋼筋混凝土。<

95、/p><p><b>　　1 介紹</b></p><p>　　每年有超過300000個地震在地球上發(fā)生。 多數(shù)地震強(qiáng)度小而且不會對我們的建筑物造成破害。然而，較大強(qiáng)度的地震如果發(fā)生在人口稠密的鄰近區(qū)域，將會造成大量的破害和人員傷亡。據(jù)估計全世界每年平均有15000個人在地震中喪身。</p><p>　　自從遠(yuǎn)古時代以來，人類已經(jīng)尋找了大量方法和手

96、段把地震引起的破壞減少到最少。建筑大師們已經(jīng)能夠建造出可以在幾個世紀(jì)中抵抗強(qiáng)烈地震的建筑物。我們的祖先在中東建造的雄偉的清真寺和橋梁至今仍然在使用中，這些大師們不知道如何地震分析，但是他們憑借優(yōu)秀的工程直覺和判斷力能夠評估過去的經(jīng)驗(yàn)。由西納在伊斯坦布爾和Edirne建造的清真寺，橋梁和學(xué)校(Medrese)不僅美麗，而且是工程的杰出作品。</p><p>　　今天與我們的祖先相比較，我們有許多優(yōu)勢。我們有更多經(jīng)驗(yàn)

97、，有高度發(fā)達(dá)的分析工具和相當(dāng)多的實(shí)驗(yàn)數(shù)據(jù)。同樣計算機(jī)使我們能夠考慮更多的不確定因素和并在分析中采用一些替代方法。</p><p>　　本論文的主要目的是為鋼筋混凝土結(jié)構(gòu)的抗震提供一些基本原則。有一些簡單的并且容易實(shí)施的抗震的基本原則。它們在地震分析和實(shí)驗(yàn)研究中，和對過去地震的觀察報告中得到不斷的發(fā)展。</p><p><b>　　2 基本原理及要求</b></p

98、><p>　　除非定義了很好的設(shè)計原理，否則不能夠舍棄基本的設(shè)計原則。 普遍接受的設(shè)計原理可以如下概述：</p><p>　　1、建筑物在小型和頻繁的地震中不能有結(jié)構(gòu)破壞，通常也不能有非結(jié)構(gòu)性破壞。</p><p>　　2、建筑物在偶然的，中等的地震中不應(yīng)該有結(jié)構(gòu)性破壞（可修復(fù)）。</p><p>　　3、建筑物在罕遇地震中不能倒塌。在這種地震中

99、，結(jié)構(gòu)不能作為處于彈性范圍內(nèi)考慮。鋼筋的屈服使得構(gòu)件在關(guān)鍵部位產(chǎn)生塑性鉸。</p><p>　　除非設(shè)計要求超出了設(shè)計原理，一般的設(shè)計原理才不會有實(shí)際意義。作者認(rèn)為設(shè)計要求可以概括為以下三組：</p><p><b>　　1、強(qiáng)度要求</b></p><p><b>　　2、延性要求</b></p><

100、p>　　3、剛度要求(位移控制)</p><p>　　這三個要求將會簡短地在下列段落中討論。</p><p><b>　　2.1 強(qiáng)度要求</b></p><p>　　結(jié)構(gòu)中的構(gòu)件應(yīng)該有足夠的強(qiáng)度來安全地承受設(shè)計荷載。由于設(shè)計者已經(jīng)熟知這一需求, 在此不再詳細(xì)討論。然而，需要指出設(shè)計者應(yīng)該通過承載力設(shè)計來避免構(gòu)件的脆性失效（1）。圖1展示