Lower Columns Research Articles

Experimental study on seismic behaviour of precast recycled fine aggregate concrete beam-column joints with pressed sleeve connections

The implementation of precast concrete and recycled aggregate concrete (RAC) for construction could achieve the purpose of high efficiency and environmental benefit. In this paper, an innovative type of precast recycled fine aggregate (RFA) concrete beam-column joint with pressed sleeve connections is introduced and investigated through experimental study, in order to explore the potential of employing RAC and pressed sleeves in new precast concrete construction. The upper and lower concrete columns and the two precast beams were prefabricated in factory using RAC, then they were assembled on-site by using pressed sleeves to connect the longitudinal reinforcements in columns. Ten 2/3-scale specimens were designed according to the current Chinese code, and were manufactured and tested under cyclic loadings. Different longitudinal reinforcement ratio (ρb = 1.03%, 1.71% and 2.09%) for beams, various replacement ratio of RFA (ω = 0, 30% and 70%) in precast concrete, different axial compression ratio (nd = 0.2 and 0.5) for joints and two manufacturing methods (precast or cast-in-situ) were considered in the specimen design. Experimental results proved the desirable performance of the proposed connection using pressed sleeves, as well as the feasibility of using recycled fine aggregate concrete in the precast elements for the beam-column joints. Most of the specimens in the experiment were subjected to beam flexure failure. The failure mode, hysteretic behaviour, skeleton curves, bearing capacity, deformation capacity, stiffness and energy dissipation of the precast beam-column joints were similar as those of the conventional monolithic cast-in-situ counterpart. The analytical methods for predicting the flexural capacity of beams in the joint and the shear capacity of core joint were recommended. The results predicted by the analytical methods had satisfactory agreement with the experimental results, which provides a reference for future further theoretical research.

Seismic performance of joint between L-shaped CFST column and H-section beam with lower plate and extended flange plate

Bolted joints are widely used in beam-to-column joints in structures due to the advantages of fast construction, convenient installation and disassembly, and resource conservation. A bolted joint configuration between L-shaped concrete-filled steel tubular column and H-section beam with lower plate and extended flange plate was proposed, realizing fully-bolted connections between the upper and lower columns, as well as between the beam and the column. Four specimens, with different bolt numbers on the beam flange or different configurations of stiffeners, had been designed and tested under cyclic loads. Finite element models were developed and validated based on the test results, and parametric analysis was performed to analyze the influence of extended flange plate thickness on the mechanical properties of the joints. According to the results, the hysteresis curves of the specimens were plump, and the slippages between the extended flange plate and the beam flange improved the ductility and energy dissipation capacity of the specimens. Increasing bolt number on the beam flange significantly increased the joint resistance and stiffness. The beam vertical stiffeners limited the development of the plastic deformation of the beam flange, thereby reducing the local buckling of the beam section. Based on the experimental and finite element analysis results, simplified calculation formulas and design procedures for the joint are proposed.

Eccentric compression behaviour of rectangular concrete-filled steel tube columns with self-compacting lower expansion concrete

The use of a self-compacting lower expansion concrete in a concrete-filled steel tube (CFST) structure not only promotes the quality of concrete pouring but also improves the bond behaviour between the steel and the concrete. In combination with the actual stress state of the columns in the engineering structure, it is necessary to study the eccentric compression behaviour of the column. In this study, experimental studies involving both uniaxial and biaxial bending tests of rectangular self-compacting lower expansion CFST columns were carried out. The variation laws of the load–displacement curves, the lateral deflection curves and the stress–strain curves during the loading phase were analysed. Furthermore, the failure modes and the mechanical properties of the specimens under eccentric compression loads were investigated. Subsequently, the numerical models of CFST columns with self-compacting lower expansion concrete were considered and established. In order to verify the rationality of the finite element modelling, the numerical calculation results were compared with test results. Then, a parametric analysis of the compression and the bending bearing capacities of each column was carried out by changing the eccentricity of the load, and the N–M curves or N-Mx-My surfaces describing the ultimate bearing capacity of the column were obtained. Finally, by the parametric finite element analysis of the rectangular CFST columns regarding to the bearing capacity under the same eccentricity, a conclusion was obtained: when the expansion agent content γ of a specimen increased from 0% to 10%, the bearing capacity of the columns increases significantly, but when continue increasing the expansive agent content, the expansion agent content has little effect on the compression–bending bearing capacity.

Behavior of End-Plate Connection with Oversize Holes and Plate Washers for Column Splice

AbstractThis study investigated the behavior of end-plate connections for column splices with construction tolerance. To adjust misalignment between upper and lower columns, oversize holes were dri...

Efficient form-finding algorithm for freeform grid structures based on inverse hanging method

Grid structures and branching columns have been widely adopted due to their high structural efficiency and novel appearance. High structural efficiency must be achieved through a strict form-finding analysis. Existing algorithms are mainly applicable for grid structures or branching columns only. However, the form-finding of upper grid structures and the lower branching columns are mutually affected. A form-finding algorithm is needed for grid structures supported by branching columns. In the present work, an efficient form-finding algorithm suitable for grid structures is initially proposed, and the feasibility of this algorithm is verified through three examples. Then, the form-finding algorithm for grid structures is integrated with the form-finding algorithm of branching columns. Results indicated that the proposed algorithm can be used for form-finding analysis of various grid structures supported by branching columns. This work was conducted using a general finite element analysis program and can be easily mastered by engineering designers while avoiding tedious programming.

Full-scale corner-supported modular steel structures with vertical inter-module connections under cyclic loading

Corner-supported steel modular buildings were constructed using volumetric modules with the inter-module connections at their corners and similar connections to foundations. The rotary inter-module connections were used to assemble a two-storey building frame in this study for investigation of its the mechanical behavior. Such a full-scale building frame was examined under cyclic loading until structural failure, where the failure mode, hysteretic performance, ductility, stiffness degradation as well as energy dissipation were experimentally clarified. The results indicated that the structure experienced ductile failure with buckling at the end of the ceiling and floor beams as well as the bottom end of lower columns. The rotary inter-module connections were able to transfer the internal forces without failure although gaps were formed between the foundation corner fitting and lower corner fitting. A refined finite element (FE) modelling approach was established and validated through comparisons to experimental results, then the load-displacement curves of such steel modular structure were obtained and analyzed under different axial compression ratios as well as stiffness effect of module-to-foundation connections. Theoretical formula was further derived to estimate the initial lateral stiffness of the upper and lower frame considering semi-rigid inter-module and module-to-foundation connections, showing well agreement with the experimental and numerical results. In this way the load transferring mechanism of such modular structure with the rotary inter-module and module-to-foundation connections can be clarified.

Defense Strategy of URWPGSim2d Simulation Platform’s Survival Challenge

In order to protect the regular fish efficiently in half-time when being the defense side in the survival challenge project, the tactics of human basketball game are introduced, and the defense strategy of urwpgsim2d simulation platform’s survival challenge is proposed, that is, the defensive strategy of the target defense based on the position of attacking fish. This paper first analyzes several problems appeared in the competition process, then, according to the rules and common problems of the competition, we formulated the survival strategies of No.2 and No.4 upper and lower double winding columns, as well as one-to-one defense of No.1 against No.3. In the process, the mathematical model of the common fish’s avoiding and one-on-one protection is established. The results of a lot of experiments show that the strategy can avoid the attack of the other party effectively, improve the defense efficiency of our side, and provide reference for other counter games in the treatment of obstacles.

Comparative assessment of TROPOMI and OMI formaldehyde observations and validation against MAX-DOAS network column measurements

Abstract. The TROPOspheric Monitoring Instrument (TROPOMI), launched in October 2017 on board the Sentinel-5 Precursor (S5P) satellite, monitors the composition of the Earth's atmosphere at an unprecedented horizontal resolution as fine as 3.5 × 5.5 km2. This paper assesses the performances of the TROPOMI formaldehyde (HCHO) operational product compared to its predecessor, the OMI (Ozone Monitoring Instrument) HCHO QA4ECV product, at different spatial and temporal scales. The parallel development of the two algorithms favoured the consistency of the products, which facilitates the production of long-term combined time series. The main difference between the two satellite products is related to the use of different cloud algorithms, leading to a positive bias of OMI compared to TROPOMI of up to 30 % in tropical regions. We show that after switching off the explicit correction for cloud effects, the two datasets come into an excellent agreement. For medium to large HCHO vertical columns (larger than 5 × 1015 molec. cm−2) the median bias between OMI and TROPOMI HCHO columns is not larger than 10 % (< 0.4 × 1015 molec. cm−2). For lower columns, OMI observations present a remaining positive bias of about 20 % (< 0.8 × 1015 molec. cm−2) compared to TROPOMI in midlatitude regions. Here, we also use a global network of 18 MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments to validate both satellite sensors for a large range of HCHO columns. This work complements the study by Vigouroux et al. (2020), where a global FTIR (Fourier transform infrared) network is used to validate the TROPOMI HCHO operational product. Consistent with the FTIR validation study, we find that for elevated HCHO columns, TROPOMI data are systematically low (−25 % for HCHO columns larger than 8 × 1015 molec. cm−2), while no significant bias is found for medium-range column values. We further show that OMI and TROPOMI data present equivalent biases for large HCHO levels. However, TROPOMI significantly improves the precision of the HCHO observations at short temporal scales and for low HCHO columns. We show that compared to OMI, the precision of the TROPOMI HCHO columns is improved by 25 % for individual pixels and by up to a factor of 3 when considering daily averages in 20 km radius circles. The validation precision obtained with daily TROPOMI observations is comparable to the one obtained with monthly OMI observations. To illustrate the improved performances of TROPOMI in capturing weak HCHO signals, we present clear detection of HCHO column enhancements related to shipping emissions in the Indian Ocean. This is achieved by averaging data over a much shorter period (3 months) than required with previous sensors (5 years) and opens new perspectives to study shipping emissions of VOCs (volatile organic compounds) and related atmospheric chemical interactions.

Keratose sponge–microbial consortia in stromatolite-like columns and thrombolite-like mounds of the Lower Ordovician (Tremadocian) Mungok Formation, Yeongwol, Korea

Lower Ordovician stromatolite-like columns and thrombolite-like mounds, composed of fossilised keratose sponges (keratolites) and microbial carbonates, are reported from the Tremadocian Mungok Formation, Yeongwol, Korea. The stromatolite-like columns, which are up to 10 cm wide and high, consist of an inner core with low-angled (10–45°) layers that are covered by high-angled (>45°) layers. The inner core is made up of millimetric layers of alternating keratolite and microbial carbonate, and microbial carbonate dominantly comprises the outer cover. The entire columns are surrounded by bioclastic packstone to grainstone. The thrombolite-like mounds are domes a maximum of 100 cm high and 40–60 cm wide embedded within lime mud and shale. These mounds consist of keratolite–microbial carbonate clots and minor lithistid sponge–microbial carbonate clots. The stromatolite-like columns were formed in a high-energy subtidal setting, in which laminoid keratolite and microbial carbonate formed the tight laminar frame columns. Continued growth of the column narrowed the intercolumnar space, resulting in higher-energy hydrodynamic conditions that limited the growth of sponges but promoted growth of microbial organisms. In contrast, thrombolite-like mounds developed in a low-energy environment below fair-weather wave base, where irregular to bulbose keratose sponges with minor lithistid sponge–microstromatolite associations formed cluster reefs. There appear to have been ecological and/or environmental factors that affected the distribution of these sponges; keratose and lithistid sponges rarely occur together in the Mungok reefs, whereas lithistids are pervasive within coeval intermediate-energy microbial reefs elsewhere. These results demonstrate the importance of hydrodynamic controls on overall reef morphology and configurations during the Early Ordovician, and suggest that keratosan–microbial consortia may have been an integral component of the Great Ordovician Biodiversification Event, together with the lithistid sponge–microbial consortium.

Seismic response analysis of the precast double-deck rocking frame bridge pier system

To improve seismic performance of double-deck frame bridge system, a novel precast double-deck rocking frame bridge pier system is developed based on ductile and rocking seismic conception design in this paper. In this novel system, the upper columns are allowed to rock between the precast cap beams to form the rocking story, while the lower columns are connected to precast cap beam and footings by grouted splice sleeve to form emulative cast-in-place story. The seismic response of this novel frame bridge pier system is investigated. Nonlinear equations of motion of the system are established following Lagrange's equation and conservation of angular momentum, and the analytical model is used to conduct case study, parametric study and stability analysis. The results show that seismic responses of the lower columns of the proposed structural system are smaller than cast-in-place bridge pier, while it has an opposite trend for upper columns. The effect of deformability of the lower story on the stability of the system is marginal for low-frequency pulses or small column size, while for high-frequency pulses or large column size the deformability jeopardizes the stability of the system.

Elastic-plastic time-history analysis of steel-tube stiff-frame arch bridge without inner filling concrete

Based on a case study of a typical arch bridge with hollow steel tube and stiffness frame located in the high intensity region of western China, this paper adopts the onlinear time- history method to analyze the structural response of the overall bridge elastic-plastic model under seismic action. Under the force of Wolong wave in Wenchuan Earthquake, the main load-bearing members of the structure have a good seismic performance. Only part of the columns on the main arch ring enter the plastic hinge state for energy dissipation, and the lower columns have a more obvious energy dissipation effect than the higher ones. The result indicates that the design idea of structure which is similar to that of strong column and weak beam in ductility design, has the characteristics of “strong arch and weak beam” and can therefore improve the ability of structure to resist collapse under earthquake action.

Experimental and numerical investigation on seismic performance of SRC variable-column exterior joints in CAP1400 NPP

The experimental and numerical investigations were carried out on conventional island steam turbine workshop of Rongcheng CAP1400 steel reinforced concrete (SRC) nuclear power plant in Shandong Province as the prototype. Four SRC variable-column exterior joints with a scale of 1/4 were designed for experimentally investigated under repetitive reversed cyclic loading. The failure process, failure modes, hysteresis loops, skeleton curves, bearing capacity and energy dissipation capacity of the joints were presented and analyzed in detail. Furthermore, finite element analyses based on ABAQUS software were performed to study the influence of different parameters on seismic performance of SRC variable-column exterior joints, and the parameters included the sectional height of SRC beam, sectional size of upper and lower columns, yield strength of section steel, axial compression ratio and steel content. Parametric researches and the tests suggested that the bearing capacity, energy dissipation and ductility of the joint were significantly affected by the sectional height of SRC beam, sectional size of upper and lower columns and steel content. The yield strength of section steel and axial compression ratio has little influence on the bearing capacity, stiffness and energy dissipation. Moreover, it was suggested that the internal section steel of the joints should be of Q345 steel grade and above, hoping to provide reference for seismic design of engineering application.

A novel erection technique of the L-shaped precast frames utilizing laminated metal plates

ABSTRACT This study aimed to demonstrate an erection of the irregular L-shaped precast frames utilizing rigid mechanical joints. Precast columns of L-shaped sections were introduced to replace rectangular columns, which do not fit inside corners; sections are preferred by architects because of their architectural flexibility at the corners of walls. The mechanical connections of steel-concrete composite precast columns were developed using irregular shaped pair of steel plates; each plate was installed at the bottom of the upper columns and on the top of the lower columns. These were then inter-connected via bolts, providing a flexural capacity that was similar to that of conventional monolithic column connections. Column rebars were spliced through metal plates. The columns and beams were also assembled into frames by extended endplates, which were, subsequently, prefabricated with precast beams. An extensive erection test of a full-scale precast frame was performed, demonstrating the efficient and effortless erection of the proposed method. The construction time compared with conventional monolithic assembly was substantially reduced, leading to a corresponding reduction in construction costs. Numerical investigation of the proposed frames was also conducted to verify the structural performance, demonstrating predictable and stable nonlinear structural behavior of the mechanical joints.

Application of green methodology to pharmaceutical analysis using eco-friendly ethanol-water mobile phases

Green analysis techniques based on solvent consumption and substitution are two major applications in greening chromatographic analysis. Decreasing the toxicity of solvents used in mobile phases by substituting them with less or non-hazardous ones or revealing the consumed amounts by using lower diameter columns or miniaturizing instruments are some examples that can be implemented to an analysis. Environmentally friendly water and ethanol based mobile phases reduce the use of toxic solvents such as methanol and acetonitrile, and consequently the necessary cleaning of waste is reduced. In the presented study, ethanol having less toxic and hazardous effects has been selected as organic modifier. Famotidin, Paracetamol and Thiocolchicoside were selected molecules for demonstration of the applicability of green HPLC in pharmaceutical analysis. Experiments were carried out using an LC system connected to a Diode Array Detection (DAD) at 254 nm. C8 (150 × 4.6 mm, 5 µm) analytical column was tested as stationary phases. In the mobile phase optimization, ethanol and sodium dihydrogen phosphate buffer contents were adjusted to the desired concentrations for the elution of selected analytes both in isocratic and gradient elution modes. Initial flow rate of the mobile phase was set to 1.0 mL/min and the injection volume was 20 µL. Developed mobile phase consisted of sodium dihydrogen phosphate (pH 4.6; 50 mM), and ethanol in gradient elution mode. All three active pharmaceutical ingredients were well separated both form baseline and each other with the capacity factors of 2.14, 2.53 and 4.26, respectively. Caffeine was selected as internal standard.The developed EtOH based mobile phase method in RP-HPLC was validated in terms of ICH requirements and found to be selective, linear, sensitive, accurate, precise, repeatable, rugged and robust. Developed method was also successful in pharmaceutical analysis of famotidin, paracetamol and thiocolchicoside from Turkish drug market. The findings of the presented study suggested that environmentally friendly ethanol and water based mobile phases could successfully apply in the pharmaceutical analysis.

Enhanced atmospheric ammonia (NH3) pollution in China from 2008 to 2016: Evidence from a combination of observations and emissions

The increase of gaseous ammonia (NH3) concentration in the atmosphere significantly impacts the regional air quality, human health, and the nitrogen cycle of ecosystems. This study aims to verify the reanalyzed product of IASI NH3 (the ANNI-NH3-v2.1R-I, hereafter referred to as IASI_NH3_R) and to analyze the spatial and temporal characteristics of atmospheric NH3 during 2008–2016 and its underlying influencing factors. Our results show a good agreement between spatial pattern and temporal (annual and monthly) trend of the satellite-derived surface NH3 concentrations and the measured near-ground NH3 measurements over different land covers in Eastern China, suggesting the IASI_NH3_R product can be used to investigate spatial and temporal trends of atmospheric NH3 concentration. The annual mean NH3 column concentrations peaked in the North China Plain (averaged 12 × 1015 mol cm−2 yr−1) and showed a significant increasing trend at a rate of 0.6 × 1015 mol cm−2 yr−1 during the entire period, which can be ascribed to densely populated, intensive agricultural activities and substantial reduction of SO2 and NO2 emissions since 2011. The NH3 column concentrations show a slight increase in winter in most regions of China, probably due to less precipitation amount and increased uncertainty for lower NH3 columns and the thermal contrast (TC). A large seasonal variation of NH3 column concentrations was observed, with the highest values in summer and the lowest in autumn. Such seasonal variation is mainly affected by seasonal differences in NH3 emissions and meteorological conditions. Our results suggest that the current control measures effectively decreased SO2 and NO2 pollution but are not yet apparent in the mitigation of atmospheric NH3 pollution, which also merits more attention considering that no effective measures are being implemented for NH3 emission control at a regional or national scale in China.

Совершенствование технологии монтажа зданий из объемных блоков со стальным каркасом методом автоматического соединения с помощью вертикальных стержней и горизонтальных пластин

It is proposed to improve the technology of erecting buildings from blocks based on using the method of automatic connection and a new composite light modular system including the advantages of both materials, concrete and steel. The authors propose using composite beams and concrete tubular columns, combining in this way the advantages of the concrete system (durability, resistance to water, higher sound insulation) with the advantages of the steel system (less weight, easier and faster installation). The scientific novelty of the method is that the vertical rods connect the columns vertically, and the plates and the horizontal draw plate connect adjacent modules horizontally. The difference between the developed solution and currently used technologies is that in this connection, the vertical connection between the upper and lower modules is carried out by a vertical rod to resist tensile forces, while the columns resist the compressive force. The shear forces between the upper and lower columns are transmitted by means of a support to the base plate, which is welded at the bottom of the column of the upper module.

High-Strength Concrete Circular Columns with TRC-TSR Dual Internal Confinement

The standard requirements for transverse steel reinforcement (TSR) confinement in reinforced-concrete (RC) columns are mainly to provide the following: ductile behavior, minimum axial load capacity of the column’s core, and prevention of longitudinal bars buckling. It is well-known that the passive confinement due the TSR action is less effective in high-strength concrete (HSC) compared to normal-strength concrete (NSC). Therefore, the TSR amounts required by the standards for HSC columns are high, and in some cases, especially in the lower stories columns of high-rise buildings, are impractical. This paper presents a new construction method using textile-reinforced concrete (TRC) as internal confinement together with reduced TSR amounts. Moreover, comparison of the proposed method with RC columns casted in fiber-reinforced polymer (FRP) stay-in-place forms as additional external confinement, is presented. Eleven large-scale column specimens were tested under axial compression. The results give an insight on the application feasibility of the proposed construction method. It is shown that the TRC-TSR dual internal confinement action can be an option to reduce the standard required TSR amounts while maintaining similar levels of ductile behavior.

Validation of OCO-2 error analysis using simulated retrievals

Abstract. Characterization of errors and sensitivity in remotely sensed observations of greenhouse gases is necessary for their use in estimating regional-scale fluxes. We analyze 15 orbits of the simulated Orbiting Carbon Observatory-2 (OCO-2) with the Atmospheric Carbon Observations from Space (ACOS) retrieval, which utilizes an optimal estimation approach, to compare predicted versus actual errors in the retrieved CO2 state. We find that the nonlinearity in the retrieval system results in XCO2 errors of ∼0.9 ppm. The predicted measurement error (resulting from radiance measurement error), about 0.2 ppm, is accurate, and an upper bound on the smoothing error (resulting from imperfect sensitivity) is not more than 0.3 ppm greater than predicted. However, the predicted XCO2 interferent error (resulting from jointly retrieved parameters) is a factor of 4 larger than predicted. This results from some interferent parameter errors that are larger than predicted, as well as some interferent parameter errors that are more strongly correlated with XCO2 error than predicted by linear error estimation. Variations in the magnitude of CO2 Jacobians at different retrieved states, which vary similarly for the upper and lower partial columns, could explain the higher interferent errors. A related finding is that the error correlation within the CO2 profiles is less negative than predicted and that reducing the magnitude of the negative correlation between the upper and lower partial columns from −0.9 to −0.5 results in agreement between the predicted and actual XCO2 error. We additionally study how the postprocessing bias correction affects errors. The bias-corrected results found in the operational OCO-2 Lite product consist of linear modification of XCO2 based on specific retrieved values, such as the CO2 grad del (δ∇CO2), (“grad del” is a measure of the change in the profile shape versus the prior) and dP (the retrieved surface pressure minus the prior). We find similar linear relationships between XCO2 error and dP or δ∇CO2 but see a very complex pattern of errors throughout the entire state vector. Possibilities for mitigating biases are proposed, though additional study is needed.

COMPOSITION AND DISTRIBUTION OF FISH LARVAE SURROUNDING THE UPWELLING ZONE IN THE WATERS OF NORTHEASTERN TAIWAN IN SUMMER

We investigated the species composition and distribution of fish larvae surrounding the upwelling zone in the waters of northeastern Taiwan in July 2011. The surface water had higher temperatures (25.7°C-28.3°C) and lower salinity (33.67-34.05 psu) than did lower water columns. A divergent trend was observed between temperature and salinity in the waters above 80 m. Moreover, we identified a cold-core eddy at the upwelling of the Kuroshio subsurface at waters approximately 60 m beneath the surface. In total, 1834 fish larvae were collected from eight stations; 85 taxa contributing to 60 families were identified. The abundance of fish larvae varied among stations. The five predominant larval taxa, which constituted 50% of the total fish larvae, were Auxis spp. (30.14%), Sciaenidae spp. (6.73%), Decapterus spp. (6.29%), Champsodon spp. (5.52%), and Gobiidae spp. (4.83%). Higher diversity and lower evenness index values were recorded in areas of high temperature and low salinity. Two larval fish assemblages, Mixed Coastal Group and Upwelling Group, were identified from a cluster analysis. Mixed Coastal Group exhibited higher density, higher temperature, and lower salinity than Upwelling Group did. Thus, in general, the density, spatial distribution, composition, and diversity of fish larvae differed, and the salinity at the 20-m layer exerted a more substantial effect on larval distribution in this study.

Effect of cervical flexion and extension on thoracic sagittal alignment.

The cervical spine has the largest sagittal motion in the whole spine, and cervical alignment affects the thoracic sagittal alignment. However, the effects of cervical flexion and extension on thoracic sagittal alignment have not been investigated in detail. The purpose of this study was to analyze the change of thoracic sagittal alignment following cervical flexion and extension. A total of 55 consecutive patients (42 men and 13 women; average age 49.1 years) who presented to our department with spinal degenerative disease between January 2016 and September 2017 were enrolled in our study. Subjects with a history of trauma, infection, tumor, inflammatory disease, ossification, or cervical deformities, and those who had undergone spinal surgery were excluded. The following parameters were analyzed: occipito-axial angle (O-C2), C2 slope (C2S), C2-C7 angle, T1 slope (T1S), thoracic kyphosis, T1-T4 angle, T5-T8 angle, T9-T12 angle, lumbar lordosis, sacral slope, pelvic tilt in cervical flexion, neutral, and extension. Cervical flexion significantly decreased O-C2, C2-C7 angles and T1S, and increased C2S. Cervical extension conversely changed these parameters. At cervical flexion, the correlation of C2-C7 angle with thoracic parameters was maintained, except for the T1-T4 angle. At cervical extension, the correlation was observed with T1S and T1-T4 angle. Cervical flexion affects the T1S and T5-T8 angle, but there is no significant change in T1-T4 and T9 and lower spino-pelvic columns. This study suggests that T2-T4 can be considered as a stable distal end when cervical long fixation for corrective surgery is performed.