本文選題：土-結構相互作用　切入點：減震　出處：《中國地質大學》2014年博士論文

【摘要】：對于建筑抗震體系,在理論分析和設計中通常忽略土-結構相互作用(SSI)。即采用剛性基礎的假定,認為地震時基礎的運動與鄰近的自由場一致。也就是說,上部結構的慣性力傳給地基,使之產(chǎn)生的變形,比地震波引起的地基變形應當小很多。否則假定不合理,基礎會產(chǎn)生相對于地基的變形,從而導致上部結構的實際運動與按照剛性基礎的假定得到的響應有較大的差別。因此,對柔性基礎上的建筑物,在計算地震響應時有必要考慮土-結構的相互作用 目前,隔震技術已經(jīng)基本成熟,土-結構相互作用(SSI)研究正在深入,而二者的耦合研究則剛剛起步,研究文獻不多,得出的結論有時還互相矛盾,因此關于隔震技術與SSI的耦合有待進一步研究。 現(xiàn)今,關于考慮SSI影響的隔震研究還限于簡單模型,結構簡化為單質點或多質點剪切結構,地基假定為彈性半空間。研究主要集中在剛性淺基礎對隔震的影響,對柔性基礎對隔震的影響研究較少,但實際橋梁和渡槽很多采用具有一定柔性的樁基。本課題對柔性地基中簡支橋梁(或渡槽)的減隔震進行研究,能夠更真實地揭示土-結構相互作用對該類橋梁減隔震系統(tǒng)的影響。 課題針對某試驗隔震渡槽(即過水的橋梁)結構和常見的三跨樁基隔震橋梁結構,研究SSI對其減隔震效果的影響。 研究內(nèi)容如下： 第一章緒論,綜述了考慮土-結構動力相互作用問題的隔震結構研究與發(fā)展以及橋梁脆弱性曲線的研究與發(fā)展。 第二章,論文對某簡支渡槽進行了比較精細的有限元分析,樁采用梁單元建模,土和樁的相互作用采用彈簧單元,槽墩、槽身及槽中的水體,采用實體建模。這樣可以得到工程上比較關注的上部結構不同部位的具體響應。通過該模型分析了實際的隔震支座對系統(tǒng)響應的的影響。 第三章,對前面的模型樁基部分,采用了不同的建模方式,并進行了動力分析比較。即樁土之間的相互作用分別采用Mindlin方法和規(guī)范推薦的m法兩種方法進行分析比較。改進的Penzien模型采用一組帶阻尼的彈簧單元來模擬自由場土層在不同深度對樁的剛度效應和阻尼效應,彈簧的一端與樁連接,另一端和一足夠大的質量單元連接,以模擬自由場地土對結構的質量效應；樁周土質量間增加了土的剪切彈簧和阻尼器；自由場地質量間也增加了土的剪切彈簧和阻尼器。 第四章,采用Mindlin方法對某渡槽擬動力試驗的結果進行了分析,說明該法有一定的可信性。實驗位于大型土槽內(nèi),設計制作了縮尺的渡槽試驗模型。模型由四根鋼管樁支撐,上部槽體模擬單跨槽體和水體的作用,采用等效質量塊代替,承臺、槽墩及槽體均采用鋼筋混凝土材料,槽墩與等效質量塊之間布有四個抗震支座。實驗主要了解樁土相互作用。本章采用三維有限元模型對實驗進行了模擬。 第五章,對不同場地土對智能隔震渡槽的影響進行了分析。 智能隔震支座由隔震支座和磁流變阻尼器構成,位于渡槽墩頂,智能隔震系統(tǒng)的控制策略為半主動控制。對此智能隔震渡槽,分析了地震作用下,不同的場地土對結構體系的影響,智能隔震裝置的有效性。 第六章,對典型的三跨簡支梁進行了隔震分析,特別考慮了橋面板之間、橋面板與橋臺之間碰撞對隔震橋梁的的影響。 前面的渡槽是簡支結構,屬于簡支橋梁類型,與普通簡支橋梁比,只是荷載不同罷了。前面的渡槽三維有限元模型比較復雜,自由度也較多。而第五章,考慮SSI的智能隔震渡槽的地震響應,其模型相對簡單,自由度也較少。事實上,模型的復雜程度變化是很大的,可以從簡單的,僅包括幾個自由度的桿件模型(如第五章),到很精細的模型,即包括各個不同桿件的非線性行為的模型。合理的模型應該與橋梁的配置、橋梁的類型、期望的地震需求和地震響應相關。 本章對典型的三跨簡支橋梁進行了建模,比較全面地考慮了地震動力分析時的需要的一些重要因素,包括材料非線性、支座非線性、土-結構相互作用以及橋面板的碰撞等,對橋面板采用梁單元建模,對關鍵的橋墩柱采用纖維單元建模,對橋面板的碰撞采用碰撞單元建模。所建三維模型,既能較好反映該類橋梁的地震動力分析的響應特點,又不至于太復雜,導致后面脆弱性分析的計算成本過高。 本章重點采用此模型,對橋面板的碰撞進行了研究,分析了碰撞對結構地震動力響應的影響,對隔震簡支橋梁的減震效果的影響。 第七章,對典型三跨簡支梁進行了脆弱性分析,比較了隔震前后的橋梁構件和橋梁系統(tǒng)的脆弱性的變化。 脆弱性是在給定地震動強度情況下,結構或結構達到或超過某個設定的損傷程度的條件概率。本章采用地震峰值加速度(PGA)作為地震動強度度量,挑選了五種地震類型中共10條地震波,每條地震以O.1g作為PGA增量來分析,共100個計算工況。 通過對各個地震波的增量時程分析,共獲得100個時程分析結果。從各時程分析中提取關注的響應變量,包括柱子曲率,固定支座位移,滑動支座位移等。這便是橋梁部件的地震需求。對這些量值進行回歸分析,可以得到響應LN (Sd)和地震峰值LN (PGA)之間的關系。再根據(jù)橋梁損失極限狀態(tài)比較,得出橋梁部件的脆弱性曲線,由此,進一步得到橋梁系統(tǒng)的脆弱性曲線。 根據(jù)支座脆弱的特點,進行堅固處理時,優(yōu)先考慮支座的替換。替換為隔震支座后,再按同樣的方法進行各地震波的增量時程分析,得出隔震橋梁的需求響應。最后,可計算出隔震橋梁部件和橋梁系統(tǒng)的脆弱性曲線。并對隔震前后的脆弱性進行比較。 第八章,給出了主要的研究結果和結論。 論文的主要成果如下： 1)渡槽結構采用減震支座后的動力響應 安裝減震支座后渡槽結構的最大動應力和內(nèi)力得到了不同程度的抑制,支座在橫槽向和順槽向滯回曲線的滯回環(huán)明顯、飽滿,表明減震支座具有明顯耗能效果。 2)不同樁土作用模型 在三維渡槽地震動力響應分析中,采用m法和Mindlin方法分別建立樁。土相互作用模型,其余相同,Mindlin方法計算的樁頂剪力和彎矩比m法略小,而樁頂位移略大,這說明兩種考慮樁-土作用的方法差別不大。而且,兩種方法對上部結構,特別是槽體影響不大,渡槽的前三階振型均為槽體的運動振型,且頻率保持不變,槽身的位移也不變,這也說明對此類結構,樁-土作用的影響對上部結構影響較小。 3)計算分析與實驗驗證 通過多種工況的計算,包括不同的地震波及不同地震波峰值,渡槽非線性有限元動力分析成果,無論是位移時程響應特征,在槽墩中部點位移響應的極值,還是樁體水平位響應值,與渡槽擬動力試驗結果都比較接近,這在一定程度上驗證了擬動力試驗的合理性和正確性,也表明采用的計算模型在中、小震條件下,能夠比較準確的模擬地震作用下的土-樁-結構-水體系統(tǒng)的地震響應。 4)對不同土體類型,SSI對減震效果的影響 有隔震支座時,考慮SSI后,槽身和墩頂?shù)乃綑M向位移略大。土越軟,橫向位移越大,但最大基底剪力,無論是軟基還是剛基,差別不大 有智能隔震系統(tǒng)時,考慮SSI后,槽身和墩頂?shù)乃綑M向位移急劇減小。這種效果可以避免位移過大,損壞水封。 有智能隔震系統(tǒng)時,考慮SSI后,最大基底剪力減小了。土越硬,基底剪力越小。 考慮SSI后的減隔震控制系統(tǒng),其控制效果不如不考慮SSI的情況。土越軟,控制效果越差。硬土和剛性基礎的控制效果相接近。故,對硬土上的基礎,可以當作剛性基礎處理,對中、軟土上的基礎,要考慮SSI效果,否者會高估減震的效果。 小阻尼隔震支座,對橫向漂移、橫向速度和最大基底剪力的減小,均比大阻尼隔震支座要好。 5)考慮SSI的典型簡支橋梁結構隔震 (1)碰撞對響應的影響： 由于地震波的不同,碰撞可能導致柱子的響應或呈增加趨勢,或者呈減小趨勢。 (2)減震效果： 從減震效果看,縱向減震效果良好,柱子的響應減小,減震支座的力-位移滯回曲線明顯,但同時明顯放大了支座以上梁的縱向瞬時加速度和梁的縱向位移。而橫向減震,不僅沒有效果,反而響應有所放大。 (3)碰撞對減震效果的影響： 考慮碰撞,對隔震支座以下部位柱子的縱向隔震影響比不考慮碰撞更有效或接近。但都放大了支座以上梁的縱向位移和加速度。對橫向,隔振支座不僅不能減震,反而增加了橫向響應,考慮碰撞產(chǎn)生的放大作用更明顯。 (4)隔震橋梁對基頻更接近的地震波,減震效果更好。 (5)對同樣的隔震支座,不同場地土情況下,土變硬后,隔震橋梁縱向地震力逐漸變大,而墩頂?shù)奈灰埔约爸锌缑姘辶旱奈灰谱兓淮蟆?6)通過對簡支橋梁的脆弱性分析,明確了薄弱環(huán)節(jié)確實首先在于固定支座,其次是滑動支座和柱子。通過采用隔震支座,可以明顯改善橋梁系統(tǒng)的脆弱性。 論文的創(chuàng)新點： 考慮土-結構相互作用對隔震橋梁的影響,以前的研究模型往往只考慮一個方向,并忽略碰撞的影響。本文采用合理的模型,可考慮兩個方向的隔震效果,同時也考慮橋面板碰撞效果的影響。 論文的章節(jié)安排如下： 第一章,緒論。對考慮SSI的減隔震研究及橋梁結構脆弱性分析進行綜述。 第二章,簡支渡槽動力數(shù)值模擬建模及減震模擬分析。包括建模及減震分析。 第三章,考慮不同樁土作用模型的簡支渡槽減震動力分析。包括兩種樁土作用的模型建模,和對模型的動力時程分析和反應譜分析比較。 第四章,對某渡槽擬動力試驗的數(shù)值模擬分析。 第五章,對不同場地土對智能隔震渡槽的影響進行了分析。 第六章,考慮碰撞的簡支橋梁在不同場地土中的隔震分析。對典型的三跨簡支梁進行了隔震分析,特別考慮了橋面板之間、橋面板與橋臺之間碰撞對橋梁隔震的影響。 第七章,簡支橋梁脆弱性分析,對典型三跨簡支梁進行了脆弱性分析,比較了隔震前后的橋梁構件和橋梁系統(tǒng)的脆弱性的變化。 第八章,結論與建議
[Abstract]:For the construction of seismic system, usually ignore the soil structure interaction in the process of analysis and design (SSI). The rigid foundation assumption, that the earthquake based motion and the adjacent free field. That is to say, the inertial force of upper structure to the foundation, so the deformation should be much smaller. The deformation caused by seismic waves than foundation. Otherwise the assumption is not reasonable, the foundation will have relative to the foundation deformation, resulting in the actual movement of the upper structure and the rigid foundation assumption according to the response obtained is different. Therefore, on the basis of flexible buildings, in the calculation of seismic response is necessary to consider the interaction of soil structure the
At present, the isolation technology has been basically mature, and the research on soil structure interaction (SSI) is deepening. The coupling research between the two has just started. There are not many studies and the conclusions sometimes are contradictory. Therefore, the coupling between the isolation technology and SSI needs further research.
Today, the research on seismic isolation to consider the impact of SSI are limited to simple model structure is simplified as single or multi particle shear structure, the foundation is assumed to be elastic half space. The research mainly focused on the rigid shallow foundation influence on isolation, less studies on the influence of flexible foundation on isolation, but the actual bridge and aqueduct with many flexible the pile foundation. The flexible foundation bridges (or aqueduct) seismic isolation research, can more accurately reveal the effect of soil structure interaction on the seismic reduction and isolation system.
Aiming at the structure of a test isolated aqueduct (the bridge over water) and the common three span pile foundation isolated bridge structure, the effect of SSI on its seismic isolation effect is studied.
The contents of the study are as follows:
In the first chapter, the research and development of the seismic isolation structure considering the soil structure dynamic interaction and the research and development of the bridge vulnerability curve are summarized.
The second chapter, the thesis carries out finite element fine analysis of a simply supported aqueduct, piles are modeled by beam elements, the interaction between soil and pile by spring elements, the pier, and the water in the tank body, by solid modeling. The specific response so that we can obtain the different parts of the upper structure concerned in the engineering of through the model analysis. The actual bearing effect on the response of the system.
The third chapter, the model of pile foundation on the front, using different modeling methods, and analyzed and compared. The two methods was that the interaction between pile and soil were determined by Mindlin method and the standard recommended m method are analyzed and compared. The improved Penzien model by a group with damping spring element to simulate the free field the soil in different depth of pile stiffness effect and damping effect, the end of the spring is connected with the other end of the pile, and a large enough quality unit connection, to simulate the free soil on the quality of the structure effect; soil quality increased between soil shear spring and damper; free field quality also increased soil shear spring and damper.
The fourth chapter, using the Mindlin method of pseudo dynamic test on an aqueduct are analyzed, the results show that the method has a certain credibility. The experiment is located in a large soil tank model was designed. The test scale aqueduct model consists of four pieces of steel pile support, the upper tank and water tank simulation of single span, equivalent mass block instead, pile caps, pier and tank adopts reinforced concrete materials, between pier and equivalent quality cloth four seismic bearing. The experiment mainly to understand the interaction between pile and soil. This chapter of the experiment was simulated using a three-dimensional finite element model.
In the fifth chapter, the influence of different site soil on the intelligent isolation aqueduct is analyzed.
Intelligent bearings by bearings and magnetic damper which is located in the aqueduct pier, the control strategy of intelligent isolation system for semi-active control. This intelligent isolation aqueduct, the effects of the earthquake under the influence of site soil of different structure system, the effectiveness of intelligent isolation device.
In the sixth chapter, the seismic isolation analysis of typical three span simple beam is carried out, especially the impact of the collision between the bridge panel and the bridge deck on the isolated bridge.
In front of the aqueduct is simple structure, which belongs to the simple bridge type, and ordinary bridges than just load is different. The three-dimensional finite element model of the aqueduct in front of the more complex, more degrees of freedom. And the fifth chapter, considering the intelligent isolation SSI seismic response of aqueduct, the model is relatively simple, less degree of freedom in fact, the complexity of the model change is very big, can from the simple, only including bar model with several degrees of freedom (such as fifth), to a fine model of nonlinear behavior which includes different bar model. The model should be reasonable and bridge configuration, the bridge type. Seismic demand and seismic response of expectations.
This chapter of the three span simply supported bridge of typical modeling, comprehensively considered the earthquake dynamic analysis to some important factors, including material nonlinear, nonlinear bearing, soil structure interaction and collision of the bridge deck, bridge deck beam element modeling, the key bridge pier by fiber unit modeling, collision of bridge deck by using collision element modeling. The three-dimensional model of seismic dynamic analysis can reflect the response characteristics of this kind of bridge, and not too complicated, leading to computational cost analysis behind the vulnerability is too high.
This chapter mainly applies this model to study the impact of bridge deck, and analyzes the impact of collision on the seismic response of structure, and the influence of isolation on simply supported bridges.
In the seventh chapter, the fragility of the typical three span simple beam is analyzed, and the changes of the vulnerability of the bridge components and the bridge system are compared before and after the shock isolation.
The vulnerability is given in the case of earthquake intensity, structure or structure to meet or exceed a certain degree of injury. This chapter uses the conditional probability of earthquake peak acceleration (PGA) as the ground motion intensity measurement, selection of the five type earthquake the 10 seismic waves, each earthquake with O.1g as PGA increment analysis. A total of 100 calculation conditions.
Based on the increment of every seismic wave time history analysis, history analysis results were obtained from 100. When the response variable in the analysis of the extraction of attention, including column curvature, fixed displacement, displacement of sliding bearings. This is part of the bridge seismic demand. These values can be obtained by regression analysis. The response of LN (Sd) and the peak LN (PGA). The relationship between the loss of bridge according to limit state, the vulnerability curve of bridge components thus obtained fragility curves of bridge system.
According to the characteristics of bearing fragile, sturdy handle, preferred bearing replacement. Replace bearings, incremental following the same method around the shock time history analysis, the response of isolated bridge demand. Finally, calculate the fragility curves of isolated bridge components and bridge system and vulnerability to. Before and after isolation were compared.
In the eighth chapter, the main research results and conclusions are given.
The main achievements of the paper are as follows:
1) the dynamic response of the aqueduct structure with the shock absorber support
After installing the damping support, the maximum dynamic stress and internal force of the aqueduct structure are restrained to varying degrees. The hysteresis loops of the bearing in the transverse groove direction and the groove loop are obvious and full, indicating that the damping bearing has obvious energy dissipation effect.
2) different pile soil interaction model
In the analysis of 3D aqueduct seismic response, using m method and Mindlin method were established. The pile soil interaction model, the same Mindlin method to calculate the pile top shear and bending moment than m slightly smaller, and the displacement of pile top is slightly larger, indicating that the two little difference method considering the pile-soil interaction and. On the upper structure, two kinds of methods, especially the impact of the aqueduct with three modes of vibration are motion type trough, and the frequency remains unchanged, displacement of aqueduct body is also unchanged, it also shows that in such structure, the interaction of soil pile superstructure of little influence.
3) calculation analysis and experimental verification
Through the calculation of various conditions, including different seismic waves and different seismic wave peak, nonlinear finite element dynamic analysis results of aqueduct, both the characteristics of response displacement, in the extreme value of displacement response of central pier, level or pile response value and aqueduct pseudo dynamic test results are relatively close, which verifies the rationality and the correctness of the pseudo dynamic test to a certain extent, also shows that the calculation model in small earthquake conditions, can simulate the earthquake accurately under the soil pile structure water system seismic response.
4) the effect of SSI on the damping effect of different soil types
There are bearings when considering SSI, transverse displacement of aqueduct and the pier top is slightly larger. In soft soil, the lateral displacement is greater, but the maximum base shear, whether it is soft or Ganj little difference.
In an intelligent isolation system, the horizontal lateral displacement of the body and the top of the pier sharply decreases after the SSI is considered. This effect can avoid excessive displacement and damage to water seal.
When the SSI is considered, the maximum base shear force decreases when the intelligent isolation system is considered. The harder the soil is, the smaller the base shear is.
Consider isolation control system after SSI, the control effect is not considered in the case of SSI. The soil is soft, the control effect is worse. The control effect of the hard soil and rigid foundation are close. Therefore, based on the hard soil, can be used as a rigid foundation, the foundation, the soft soil, to considering the SSI effect, it will overestimate the damping effect.
The decrease of the lateral drift, the lateral velocity and the maximum base shear is better than the large damping isolation bearing.
5) seismic isolation of typical simple supported bridge structures considering SSI
(1) the impact of the collision on the response:
Due to the difference of seismic waves, collisions may lead to an increase in the response of the column, or a decreasing trend.
(2) the effect of shock absorption:
From the damping effect, longitudinal good cushioning effect, reduce post response, bearing force displacement hysteresis curve is obvious, but also significantly enlarge the vertical displacement of the longitudinal beam above and the instantaneous acceleration of bearing beam. And the transverse vibration, not only has no effect, but the response has been enlarged.
(3) impact on the effect of shock absorption:
Consider the collision, vertical isolation influence on the bearings below the column is more effective than that without considering the collision or close. But the longitudinal displacement and acceleration amplification support above beam. On the transverse vibration isolator, not only shock, but increased the transverse response, considering the collision produced by the amplification effect is more obvious.
(4) the seismic waves which are closer to the base frequency of the isolated bridge are better in shock absorption.
(5) for the same isolation bearings and soil under different soil conditions, the longitudinal seismic force of the isolated bridge gradually increases, while the displacement of the pier top and the displacement of the mid span face slab change little.
6) through the analysis of the vulnerability of simply supported bridges, it is clear that the weak links do first lie in the fixed bearings, followed by the sliding bearings and columns. By adopting the isolation bearings, the vulnerability of the bridge system can be obviously improved.
The innovation of the thesis:
Considering the influence of soil structure interaction on isolated bridges, the previous research models usually only consider one direction and ignore the impact of collision. In this paper, a reasonable model can be used to consider the isolation effect in two directions, and the impact of bridge deck impact is also considered.
The chapters of the paper are arranged as follows:
In the first chapter, the introduction. A review of the research on the isolation of SSI and the analysis of the structural vulnerability of the bridge is made.
The second chapter, the dynamic numerical simulation modeling and the shock absorption simulation analysis of the simply supported aqueduct, including the modeling and the shock absorption analysis.
In the third chapter, we consider the dynamic analysis of simply supported aqueducts with different pile-soil interaction models, including two kinds of pile soil interaction model modeling, and the dynamic time history analysis and response spectrum analysis of the model.
In the fourth chapter, the pseudo dynamic test of a aqueduct

【學位授予單位】：中國地質大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：U442.55;P315.9

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