Effects of foundation rocking and uplifting on displacement amplification factor

Prediction of displacement demand to assess seismic performance of structures is a necessary step where nonlinear static procedures are followed.While such predictions have been well established in literature for fixed-base structures,fewer bodies of researches have been carried out on the effect of rocking and uplifting of shallow foundations supported by soil,on such prediction.This paper aimed to investigate the effect of soil structure interaction on displacement amplification factor C1 using the beam on nonlinear Winkler foundation concept.A practical range of natural period,force reduction factors,and wide range of anticipated behavior from rocking,uplifting and hinging are considered and using thousands nonlinear time history analysis,displacement amplification factors are evaluated.The results indicate that the suggested equations in current rehabilitation documents underestimate displacement demands in the presence of foundation rocking and uplift.Finally,using regression analyses,new equations are proposed to estimate mean values of C1.

Dynamic amplification factors for a system with multiple-degrees-of-freedom

It is well-known that the responses of a structure are different when subjected to a static load or a sudden step load.The dynamic amplification factor(DAF),which is defined as the ratio of the amplitude of the vibratory response to the static response,is normally used to depict the dynamic effect.For a single-degree-of-freedom system(SDOF)subjected to a sudden dynamic load,the maximum value of DAF is 2.Many design guidelines therefore use 2 as an upper bound to consider the dynamic effect.For a civil engineering structure,which is normally a multiple-degrees-of-freedom(MDOF)system,the DAF may exceed 2 in certain circumstances.The adoption of 2 as the upper bond as suggested by the design guidelines therefore may lead to unsafe structural design.Very limited studies systematically investigate the DAF of a MDOF sysCorrespondence to:Bi Kaiming,Centre for Infrastructure Monitoring and Protection,School of Civil and Mechanical Engineering,Curtin University,Kent Street,Bentley WA 6102,Australia Tel:(+61)892665139 E-mail:kaiming.bi@curtin.edu.autem.This study theoretically investigates the DAF of a MDOF system when it is subjected to a step load based on the fundamental theory of structural dynamics.The condition on which the DAF may exceed 2 is defined.Two numerical examples and one experimental study of a cable-stayed bridge subjected to sudden cable loss are presented to illustrate the problem.

Deflection amplification factor for estimating seismic lateral deformations of RC frames

Different values have been assigned to the ratio of the defl ection amplifi cation factor(Cd) to the response modifi cation factor(R) for a specifi ed force-resisting system in the seismic design provisions while the same application is defi ned for it. An analytical study of the seismic responses of several reinforced concrete frames subjected to a suite of earthquake records performed in this research indicate that the stories’ overstrength and stiffness distribution along the structural height can affect local defl ections more than global ones. Therefore, the Cd/R ratio is calculated based on the ratio of both maximum inelastic to maximum elastic displacements and interstory drifts. Due to damage concentration in some specifi c stories, the defl ection amplifi cation factor calculated based on inelastic interstory drifts was larger than that of the inelastic displacements. Consequently, a minimum value of 1.0 is recommended for the Cd/R ratio in order to estimate maximum inelastic drifts. The ratio of inelastic to elastic displacement was generally found to increase slightly along the structural height for the studied RC models. In addition, it was detected that the story damage indices of the studied RC frames decrease when the inverted value of inelastic interstory drift ratios are increased through a(negative) power form.

Modified Sadowski formula-based model for the slope shape amplification effect under multistage slope blasting vibration

Blasting operations,which are crucial to open-pit mine production due to their simplicity and efficiency,require precise control through accurate vibration velocity calculations.The conventional Sadowski formula mainly focuses on blast center distance but neglects the amplification effect of blasting vibration waves by terraced terrain,from which the calculated blasting vibration velocities are smaller than the actual values,affecting the safety of the project.To address this issue,our model introduces the influences of slope and time into Sadowski formula to measure safety through blast vibration displacement.In the northern section of the open-pit quartz mine in Jinchang City,Gansu Province,China,the data of a continuous blasting slope project are referred to.Our findings reveal a noticeable vibration amplification effect during blasting when a multi-stage slope platform undergoes a sudden cross-sectional change near the upper overhanging surface.The amplification vibration coefficient increases with height,while vibration waves within rocks decrease from bottom to top.Conversely,platforms without distinct crosssectional changes exhibit no pronounced amplification during blasting.In addition,the vibration intensity decreases with distance as the rock height difference change propagates.The results obtained by the proposed blast vibration displacement equation incorporating slope shape influence closely agree with real-world scenarios.According to Pearson correlation coefficient(PPMCC)analysis,the average accuracy rate of our model is 88.84%,which exceeds the conventional Sadowski formula(46.92%).

Amplification of chromosome 21q22.3 harboring trefoil factor family genes in liver fluke related cholangiocarcinoma is associated with poor prognosis

AIM： To determine allelic imbalance on chromosomal region 21q22-qter including trefoil factor family genes （TFF） in cholangiocarcinoma （CCA） patients and analyze the correlation between allelic imbalances and clinicopathological parameters. METHODS： Quantitative PCR amplification was performed on four microsatellite markers and trefoil factor family genes （TFF1, TFF2, and TFF3） using a standard curve and SYBR Green I dye method. The relative copy number was determined by DNA copy number of tested locus to reference locus. The relative copy number was interpreted as deletion or amplification by comparison with normal reference range. Associations between allelic imbalance and clinicopathological parameters of CCA patients were evaluated by χ^2-tests. Kaplan-Meier method was used to analyze survival. RESULTS： The frequencies of amplification at D21S1890, D21S1893, and TFF3 were 32.5%, 30.0%, and 28.7%, respectively. Patients who had amplification at regions covering D21S1893, D21S1890, and TFF showed poor prognosis, whereas patients who had deletion showed favorable prognosis （mean： 51.7 wk vs 124.82 wk, P = 0.012）. Multivariate Cox regression analysis revealed that amplification of D21S1893, D21S1890 and TFF, blood vessel invasion, and staging were associated with poor prognosis. CONCLUSION： D21S1893-D21S1890 region may harbor candidate genes especially TFF and serine protease family, which might be involved in tumor invasion and metastasis contributing to poor survival. The amplification in this region may be used as a prognostic marker in the treatment of CCA patients.

Assessment of seismic amplification factor of excavation with support system

Retaining walls have been used in many construction projects such as for road and inclined surfaces protection. The damage caused by an earthquake depends on the fundamental frequency, amplitude and the duration of the seismic motion. These parameters strongly depend on the seismic properties of the layers that are near the surface. In the study of retaining walls, in addition to the infl uence of soil, the infl uence of topography is also important. In the present study, site response analysis is performed by using fi nite element software PLAXIS to obtain the eff ect of various factors such as embedded length of the sheet pile, underground water table, length and angle of the nail, shear wave velocity of soil on site eff ect and dynamic response. Moreover, for better understanding of the eff ect of the above parameters, the stability analysis was performed by using shear reduction method. The results show that an increase in the embedded length of the sheet pile and the length of nailing causes an increase in the amplifi cation factor. Moreover, for shear-wave velocity in the range of 200- 600 m/s, the amplifi cation factor increases with increase of the shear-wave velocity due to the decrease of nonlinear behavior.

Determination of the Amplification Factor for 2-Hydroxy-ethylperoxy Radicals in PERCA

A new method is proposed to determine the amplification factor for 2-hydroxy ethylperoxy radicals （HOC2H4O2·） in chemical amplifier. The radical source comes from the reaction of excess ethene with HO· radicals generated in the photolysis of water vapor at the wave length of 185 nm in air in a flow tube. This produces a radical source which contains equal amount of HO2·and HOC2H4O2·. The amplification factor is derived from the slopes of the lines between produced NO2 in chemical amplifier and total initial radical concentrations measured for the source of HO2· and that of the same amount of HO2· and HOC2H4O2· respectively. The amplification factor of HOC2H4O2· was similar to that of HO2·, indicating that HOC2H4O2· can be measured with the same sensitivity as HO2· by chemical amplifier.

Development of Detailed Micro-Land Form Database and Its Application to Site Amplification Characteristics in Kanagawa Prefecture, Japan

Structural characteristic of surface soil ground has great effect on the ground motion amplitude when earthquake happens. Recent studies in Japan on seismic zonings use a database that covers entire Japan with 1 km mesh size, which is useful for prefecture scale researches. However, it is hard, even with 500 m or 250 m mesh sizes to consider a city, a county or award as scale studies. Kanagawa Prefecture is highly urbanized and vulnerable to seismic disaster. The prefecture suffered a wide spread damage during the 1923 Kanto earthquake. In this paper, we deploy a very fine mesh 50 × 50 m mesh to develop a general seismic intensity map useful for micro scale disaster management for local governments and educational information for earthquake preparedness promotion. In this paper, first we prepared two detailed databases for 50 × 50 m mesh size over entire Kanagawa Prefecture. One was for geologic formations and the other the geomorphologic condition. Then these databases were used for preparation of high-resolution digital soil classification maps for 15 categories of micro landforms of prefecture. The later database was used for mapping the site amplification factors for 50 × 50 m mesh by applying the empirical relations for AVS30. We could create a GIS platform with sufficient accuracy to consider potential risk analysis.

Effect of site amplification on inelastic seismic response

The available models for eff ective periods of site and structure are reviewed in context of frequency tuning in the inelastic seismic response of soil-structure system. The eff ect of seismic intensity and ductility demand, on the eff ective periods, is investigated, and inelastic site amplifi cation is shown to be strongly correlated to the normalized eff ective period. Two non-dimensional parameters, analogous to the conventional site amplifi cation factors in codes, are defi ned to quantify the inelastic site amplifi cation. It is shown that the inelastic site amplifi cation factor (i.e. ratio of constant ductility spectral ordinates at soil site to those at rock outcrop) is able to represent the site eff ects more clearly, as compared to the inelastic site amplifi cation ratio (i.e. ratio of inelastic spectral ordinates at soil site to the corresponding elastic spectral ordinates at rock outcrop). Further, the peak in the amplifi cation factor corresponding to the eff ective site period diminishes rapidly with increasing ductility demand.

Amplification Effect of Peak Ground Motion Acceleration in ClassⅡ and Ⅲ Sites over Shandong Province

In this paper, the amplification factor （ks ） of peek ground motion with different exceedance probability in class Ⅱ and Ⅲ sites over Shandong Province was estimated by analyzing the seismic response data of soil layers collected from 358 boreholes of class Ⅱ sites and 140 boreholes of class Ⅲ site. From the results, one can conclude that： （1） The scatter plot of ks generally obeys a normal distribution ; （2） ks decreases with the increase of the strength of input ground motion, which is more apparent in Class Ⅲ site than in class lI site; （3） for class Ⅱ site, with the increase of depth of the bedrock interface where ground motion inputs, ks increases gradually until to a stable value when the depth reaches up to approximately 20 meters or larger. Yet, for class Ⅲ site, ks is insensitive to the depth; （4） the average of ks for class Ⅱ site is 1.47, slightly larger than that used in the Seismic Ground Motion Parameters Zonation Map of China （ GB 18306-2001 ）. Also, ks in class Ⅱ and Ⅲ sites at different levels of peak ground acceleration over Shandong Province is preliminarily discussed in the paper.

Sensitivity of Pion versus Parton-Jet Nuclear Modification Factors to the Path-Length Dependence of Jet-Energy Loss at RHIC and LHC

We compare the jet-path length and beam-energy dependence of the pion nuclear modification factor and a patton-jet nuclear modification factor at RHIC and LHC, and contrast the predictions based on a linear pQCD and a highly non-linear hybrid AdS holographic model of jet-energy loss. It is found that both models require a reduction of the jet-medium coupling from RHIC to LHC to account for the measured pion nuclear modification factor. In the case of the parton-jet nuclear modification factor, however, which serves as a lower bound for the LO jet nuclear modification factor of reconstructed jets, the extracted data can be characterized without a reduced jet-medium coupling at LHC energies. It is concluded that when the reconstructed jets are sensitive to both quarks and gluons and thus provide more information than the pion nuclear modification factor, their information regarding the jet-medium coupling is limited due to the superposition with NLO and medium effects. Hence, a detailed description of the underlying physics requires both the leading hadron and the reconstructed jet nuclear modification factor. Unfortunately, the results for both the pion and the parton-jet nuclear modification factor are insensitive to the jet-path dependence of the models considered.

Therapeutic strategies targeting the epidermal growth factor receptor signaling pathway in metastatic colorectal cancer

More than 1.9 million new colorectal cancer(CRC)cases and 935000 deaths were estimated to occur worldwide in 2020,representing about one in ten cancer cases and deaths.Overall,colorectal ranks third in incidence,but second in mortality.More than half of the patients are in advanced stages at diagnosis.Treatment options are complex because of the heterogeneity of the patient population,including different molecular subtypes.Treatments have included conventional fluorouracil-based chemotherapy,targeted therapy,immunotherapy,etc.In recent years,with the development of genetic testing technology,more and more targeted drugs have been applied to the treatment of CRC,which has further prolonged the survival of metastatic CRC patients.

Correlation of human epidermal growth factor receptor 2 expression with clinicopathological characteristics and prognosis in gastric cancer

AIM:To investigate human epidermal growth factor receptor 2(HER2) gene amplification and protein expression in Chinese patients with resectable gastric cancer and the association with clinicopathological characteristics and survival.METHODS:One hundred and ninety-seven gastric cancer patients who underwent curative surgery procedures were enrolled into this study.HER2 gene amplification and protein expression were examined using fluorescence in-situ hybridization(FISH) and immunohistochemistry(IHC) analysis on formalin-fixed paraffinembedded gastric cancer samples from all patients.For scoring,Hofmann's HER2 gastric cancer scoring system was adopted.All cases showing IHC3+ or FISH positiv-ity were defined as HER2 positive.Patient clinicopathological data and survival information were collected.Finally,χ 2 statistical analysis was performed to analyze the HER2 positivity rate amongst the subgroups with different clinicopathological characteristics including;gender,age,tumor location,Lauren classification,differentiation,TNM staging,depth of invasion,lymph node metastases and distant metastasis.The probability of survival for different subgroups with different clinicopathological characteristics was calculated using the Kaplan-Meier method and survival curves plotted using log rank inspection.RESULTS:According to Hofmann's HER2 gastric cancer scoring criteria,31 cases(15.74%) were identified as HER2 gene amplified and 19 cases(9.64%) were scored as strongly positive for HER2 membrane staining(3+),25 cases(12.69%) were moderately positive(2+) and 153 cases(77.66%) were HER2 negative(0/1+).The concordance rate between IHC and FISH analyses was 88.83%(175/197).Thirty-six cases were defined as positive for HER2 gene amplification and/or protein expression,with 24 of these cases being eligible for Herceptin treatment according to United States recommendations,and 29 of these cases eligible according to EU recommendations.Highly consistent results were detected between IHC3+,IHC0/1 and FISH(73.68% and 95.42%),but low consistency was observed between IHC2+ and FISH(40.00%).The positivity rates in intestinal type and well-differentiated gastric cancer were higher than those in diffuse/mixed type and poorly-differentiated gastric cancer respectively(28.57% vs 13.43%,P = 0.0103;37.25% vs 11.64%,P < 0.0001),but were not correlated with gender,age,tumor location or TNM stage,depth of invasion,lymph node metastases and distant metastasis.In poorly-differentiated gastric cancer patients,those without lymph node metastasis showed a higher HER2 positivity rate than those with lymph node metastasis(26.47% vs 7.14%,P = 0.0021).This association was not present in thosepatients with well-differentiated gastric cancer(28.57% vs 43.33%,P = 0.2832).Within our patient cohort,26 cases were lost to follow-up.The median survival time for the remaining 171 patients was 18 mo.The median survival times of the HER2 positive and negative groups were 17 and 18.5 mo respectively.Overall survival was not significantly different between HER2-positive and negative groups(χ 2 = 0.9157,P = 0.3386),but in patients presenting well-differentiated tumors,the overall survival of the HER2-positive group was significantly worse than that of the HER2-negative group(P = 0.0123).In contrast,patients with poorly differentiated and diffuse/mixed subtype gastric cancers showed no significant differences in overall survival associated with HER2.Furthermore,the median survival time of the HER2 positive group did not show any statistically significant differences when compared to the subgroups of gender,age,tumor location,TNM classification,lymph node metastases and distant metastasis.CONCLUSION:Patients with intestinal type gastric cancer(GC),well-differentiated GC and poorly-differentiated GC without lymph node metastasis,may all represent suitable candidates for targeted therapy using Herceptin.

Human epidermal growth factor receptor type 2 protein expression in Chinese metastatic prostate cancer patients correlates with cancer specific survival and increases after exposure to hormonal therapy

Aim： To investigate human epidermal growth factor receptor type 2 （HER2） protein expression and gene amplification in Chinese metastatic prostate cancer patients and their potential value as prognostic factors. Methods： Immunohistochemistry （IHC） was performed to investigate HER2 protein expression in prostate biopsy specimens from 104 Chinese metastatic prostate cancer patients. After 3-11 months of hormonal therapy, 12 patients underwent transurethral resection of the prostate （TURP）. HER2 protein expression of TURP specimens was compared with that of the original biopsy specimens. Of these, 10 biopsy and 4 TURP specimens with HER2 IHC staining scores ≥ 2＋ were investigated for HER2 gene amplification status by fluorescent in situ hybridization （FISH）. Results： Of the 104 prostate biopsy specimens, HER2 protein expression was 0, 1＋, 2＋ and 3＋ in 49 （47.1%）, 45 （43.3%）, 8 （7.7%） and 2 （1.9%） cases, respectively. There was a significant association between HER2 expression and Gleason score （P = 0.026）. HER2 protein expression of prostate cancer tissues increased in 33.3% of patients after hormonal therapy. None of the 14 specimens with HER2 IHC scores 〉 2＋ showed HER2 gene amplification. Patients with HER2 scores 〉 2＋ had a significantly higher chance of dying from prostate cancer than those with HER2 scores of 0 （P = 0.004） and 1＋ （P = 0.034）. Multivariate Cox regression analysis showed that HER2 protein expression intensity was an independent predictor of cancer-related death （P = 0.039）. Conclusion： An HER2 IHC score 〉 2＋ should be defined as HER2 protein overexpression in prostate cancer. Overexpression of HER2 protein in cancer tissue might suggest an increased risk of dying from prostate cancer. HER2 protein expression increases in some individual patients after hormonal therapy.

Epidermal growth factor receptor mutation analysis in cytological specimens and responsiveness to gefitinib in advanced non-small cell lung cancer patients

Background： Epidermal growth factor receptor（EGFR） mutation is the key predictor of EGFR tyrosine kinase inhibitors（TKIs） efficacy in non-small cell lung cancer（NSCLC）. We conducted this study to verify the feasibility of EGFR mutation analysis in cytological specimens and investigate the responsiveness to gefitinib treatment in patients carrying EGFR mutations.Methods： A total of 210 cytological specimens were collected for EGFR mutation detection by both direct sequencing and amplification refractory mutation system（ARMS）. We analyzed EGFR mutation status by both methods and evaluated the responsiveness to gefitinib treatment in patients harboring EGFR mutations by overall response rate（ORR）, disease control rate（DCR） and progression free survival（PFS）.Results： Of all patients, EGFR mutation rate was 28.6%（60/210） by direct sequencing and 45.2%（95/210） by ARMS（P〈0.001） respectively. Among the EGFR wild type patients tested by direct sequencing, 26.7% of them were positive by ARMS. For the 72 EGFR mutation positive patients treated with gefitinib, the ORR, DCR and median PFS were 69.4%, 90.2% and 9.3 months respectively. The patients whose EGFR mutation status was negative by direct sequencing but positive by ARMS had lower ORR（48.0% vs. 80.9%, P=0.004） and shorter median PFS（7.4 vs. 10.5 months, P=0.009） as compared with that of EGFR mutation positive patients by both detection methods. Conclusions： Our study verified the feasibility of EGFR analysis in cytological specimens in advanced NSCLC. ARMS is more sensitive than direct sequencing in EGFR mutation detection. EGFR Mutation status tested on cytological samples is applicable for predicting the response to gefitinib. Abundance of EGFR mutations might have an influence on TKIs efficacy.

Abnormal expression of vascular endothelial growth factor (VEGF) and its clinical features in tissues of human lung cancer

Objective： Angiogennesis, the formation of new blood vessels from the existing vascular bed, is essential step for growth and invasion of primary rumor. Vascular endothelial growth factor （VEGF） is known to play crucial role in tumor angiogenesis. In the present study, we investigate the expression of VEGF and VEGF-mRNA in the angiogennesis, metastasis and prognosis of lung cancer. Methods： The VEGF cellular distributions and expression in 38 specimens of patients with lung cancer were investigated with immunohistochemistry stain technology. The total RNAs in 38 tissues of lung cancer was measured, then the levels of VEGF-mRNA expression were analyzed by a reverse-transcription polymerase chain reaction （RT-PCR） assay. The levels of VEGF in sera of patients with lung cancer, benign lung diseases and healthy controls were detected through Enzyme linked immunosorbent assay （ELISA） method. Results： The VEGF positive stain was 76% in 38 cases of lung cancer specimens. The 89% rate of VEGF stain was found for clinical stage Ⅲ cases and 92% for stage Ⅳ lung cancers. The significantly higher expression of VEGF was evidenced in patients with lymph node metastasis （84%）, distant metastasis （90%）, and lung cancers with lower histological differentiation （89%）, respectively. The expression level of total RNA was significantly higher in patients with lung cancers than that in their paracancerons or distant lung tissues. The VEGF expressions were tightly correlated with total RNA concentration of lung carcinoma （ P 〈 0.01 ）. The predominant expressions of VEGF121 and VEGF165 gene fragments were found in lung cancer specimens by RT-PCR analysis. No significant difference of serum VEGF levels was detected between cases with lung cancer and patients with benign diseases. However, the VEGF level of cases with benign diseases was decreased significantly after patients with anti-inflammation medication. Conclusion： The present data suggested that the rumor tissue VEGF expression and VEGF-mRNA analysis in patients with lung cancer be a useful indicator for angiogenesis and metastasis of lung cancer.

Overexpression of insulin-like growth factor-Ⅰ receptor as a pertinent biomarker for hepatocytes malignant transformation

AIM: To investigate the dynamic features of insulin-like growth factor-I receptor (IGF-IR) expression in rat hepatocarcinogenesis, and the relationship between IGF-IR and hepatocytes malignant transformation at mRNA or protein level.METHODS: Hepatoma models were made by inducing with 2-fluorenylacetamide (2-FAA) on male Sprague-Dawley rats. Morphological changes of hepatocytes were observed by pathological Hematoxylin and eosin staining, the dynamic expressions of liver and serum IGF-IR were quantitatively analyzed by an enzyme-linked immunosorbent assay. The distribution of hepatic IGF-IR was located by immunohistochemistry. The fragments of IGF-IR gene were amplified by reverse transcription-polymerase chain reaction, and confirmed by sequencing.RESULTS: Rat hepatocytes after induced by 2-FAA were changed dynamically from granule-like degeneration, precancerous to hepatoma formation with the progressing increasing of hepatic mRNA or IGF-IR expression. The incidences of liver IGF-IR, IGF-IR mRNA, specific IGF-IR concentration (ng/mg wet liver), and serum IGF-IR level (ng/mL) were 0.0%, 0.0%, 0.63 ± 0.17, and 1.33 ± 0.47 in the control; 50.0%, 61.1%, 0.65 ± 0.2, and 1.51 ± 0.46 in the degeneration; 88.9%, 100%, 0.66 ± 0.14, and 1.92 ± 0.29 in the precancerosis; and 100%, 100%, 0.96 ± 0.09, and 2.43 ± 0.57 in the cancerous group, respectively. IGF-IR expression in the cancerous group was significantly higher (P < 0.01) than that in any of other groups at mRNA or protein level. The closely positive IGF-IR relationship was found between livers and sera (r = 0.91, t = 14.222, P < 0.01), respectively.CONCLUSION: IGF-IR expression may participate in rat hepatocarcinogenesis and its abnormality should be an early marker for hepatocytes malignant transformation.

Human Vascular Endothelial Growth Factor cDNA Cloning and Expression in Osteoblasts

Human vascular endothelial growth factor cDNA was amplified by nested polymerase chain reaction method from the HL60 cells. Then a pCD hVEGF 165 recombinant plasmid was constructed. Rabbit osteoblasts were transfected with pCD hVEGF 165 plasmid by lipofectin mediated gene transfer. The transient expressive results were detected by immunohistochemical method. It was observed that the expression of human VEGF gene was detected 72 h after transfecting distinctly.

400 km/h高铁桥上直立式声屏障的列车风致振动

高铁列车提速使声屏障动力问题凸显.以列车高速行驶时引发的直立式声屏障的动力放大系数为研究对象,探究直立式声屏障结构的振动特性及影响参数.首先,建立高铁桥上直立式声屏障有限元模型,分析其基本动力特性;然后,开展声屏障在400 km/h移动列车脉动风荷载时程作用下的振动规律研究,据此计算声屏障钢结构的动力放大系数;最后,针对声屏障的振动响应和动力放大系数开展多参数分析.结果表明:车速400 km/h时,5.0 m高声屏障立柱的动力放大系数约为2.76;声屏障安装位置距轨道中心线距离从3.8 m增大到4.7 m,弯矩响应的动力放大系数减小了0.3;2.3、3.3、5.0 m高声屏障立柱弯矩响应的动力放大系数分别为1.64、2.52、2.76,顶部的横向位移由0.45 mm增大至3.80 mm,根部弯矩则分别提高了26.8%和60.8%,增大声屏障高度不利于结构的振动特性.

基于黑龙江经验场地模型的地震动放大效应研究

局部场地效应是抗震设计规范中的重要内容,以场地类别为基础的场地效应划分结果较为粗略。为解决这一问题,以黑龙江地区土层分布及其剪切波速、土动力特性和密度等资料为基础,统计出场地土参数随深度的变化特征,利用统计结果建立深度从10~80 m不等的15个经验场地模型。以黑龙江地区典型基岩加速度反应谱为目标谱,人工合成地震动作为输入,为了消除随机相位的影响,每一目标谱合成400条地震动加速度时程。分别计算这15个经验场地模型的地震反应,得到不同超越概率水准下地表峰值加速度统计值以及加速度反应谱标定谱的动力放大系数统计值。计算结果表明:随着场地厚度的增加,场地周期在逐渐增加,场地峰值地面加速度(peak ground acceleration,PGA)放大倍数呈现减小的趋势;随输入地震动强度的增加,场地PGA放大倍数减小的趋势呈现出非线性,动力放大系数随场地覆盖层变厚呈现先减小后增大的趋势;随着地震动强度的增加,动力放大系数逐渐减小且随土层厚度的变化趋势趋于平缓。动力放大系数结果不是定值2.5,场地较薄并且地震动较小的情况下,动力放大系数远超2.5;场地较厚并且地震动较强时,动力放大系数大多趋于2.5。