Chinese Design Code Research Articles

Prediction of the long-term settlement of the structures built on a reclaimed coral reef island: an aircraft runway

Airport runways built on reclaimed coral calcareous sand foundation on coral reef islands is a type of important infrastructure for marine science observation, marine disaster relief, and marine supplies. Creep behavior of coral calcareous sand foundation under long-term loading applied by overlying structures could cause continuous foundation settlement; and excessive settlement may affect the normal service ability of airport runways built on coral reef islands. In this study, it is aimed to predict the long-term settlement of an airport runway built on a reclaimed coral reef island in the South China Sea (SCS) adopting a finite element method. Firstly, two improved Burgers creep models are proposed based on some laboratory triaxial test results; and then, they are embedded into the finite element software ABAQUS using the User Material Subroutine (UMAT) interface. Secondly, the two proposed improved Burgers creep models are validated by a series of triaxial creep tests for the coral calcareous sands sampled from a reclaimed coral reef island in SCS. Meanwhile, the parameters describing the creep behavior of the coral calcareous sands in SCS are calibrated for the subsequent numerical analysis. Thirdly, the long-term settlement of an airport runway built on a reclaimed coral reef island in SCS is numerically predicted adopting the two proposed improved Burgers creep models and the calibrated parameters. The computational results show that the settlement of the airport runway is in the range of 6.7 to 19.9 mm in the future 50 years, satisfying the requirement of Chinese design code MH/T 5027-2013. Finally, parametric analysis is performed to screen the significance and sensitivity of the parameters describing the creep behavior of the coral calcareous sands.

Seismic hazard assessment for mainland China based on spatially smoothed seismicity

Probabilistic seismic hazard assessment for mainland China is carried out by using spatially smoothed seismic source models obtained using the historical earthquake catalogue and two kernel smoothing techniques. The first one smooths the cumulative event count and the second one smooths the earthquake occurrence rate. For the analysis, the completeness of the catalogue is assessed and the k-mean seismic analysis results are used to aid the assignment of the regions. It is shown that the estimated parameters for the Gutenberg-Richter relation by using the maximum likelihood–based approach are consistent with those estimated by using the least-squares based approach by considering unequal observation periods. The developed seismic hazard maps indicate that the use of the smoothed source model obtained by smoothing the cumulative event count leads to spatially smeared seismic hazard. The use of the smoothed source model obtained based on smoothing the occurrence rate results in the seismic hazard map to have more spatial details. The seismic hazard assessment results indicate that, on average, the ratio of the 2475-year to 475-year return period values of PGA is about 2 and the ratio of the 2475-year to 50-year return period values of PGA is about 8. These ratios are associated with large scatters. A comparison of the normalized UHS and the Chinese design code recommended standardized design spectrum indicates that the latter is conservative as compared to the former for vibration periods outside of 0.1 to 0.2 s, and that the shape of the latter differs from that of former.

Discussion on the allowable safety factor of slope stability for high rockfill dams in China

The allowable safety factors of slope stability for rockfill dams in Chinese design codes are defined irrespective of dam heights and are mainly based on the engineering experiences with respect to the rockfill dams which are lower than 200 m. It is well known that safety margins for different structures are not comparable when safety factors are taken as the measure of safety margin. Thus whether the current allowable safety factors are applicable to the rockfill dams with heights of over 200 m has been controversial in the engineering and academic field. Reliability is well known as a unified measure of safety margin for different structures. Therefore, the slope safety margins of rockfill dams with different heights can be compared in terms of slope reliability indices derived from probabilistic methods. Based on the statistical analysis of nonlinear shear strength parameters of rockfills from 14 Chinese dams, the slope reliabilities of fictitious rockfill dams of different heights designed with equal allowable safety factor are calculated and compared in this paper. It is shown that the slope failure risk of higher dams is larger than that of lower dams if the dams are designed with equal allowable safety factor rather than equal reliability. Therefore, from the perspective of maintaining consistent slope reliability levels among rockfill dams with different heights, the allowable safety factors should be prescribed in terms of dam height, i.e. the allowable safety factor for higher dams should be larger than that for lower dams.

Shaking Table Tests of a Reinforced Concrete Frame Subjected to Mainshock-Aftershock Sequences

ABSTRACT This paper presents the shaking table tests for a 1/5-scale 5-story reinforced concrete (RC) frame subjected to mainshock (MS)-aftershock (AS) sequences for investigating the unfavorable effects of ASs on structural performance. The prototype of the test specimen, which was heavily damaged in Mw 7.9 Wenchuan earthquake, was a teaching building designed and built according to the old version of Chinese design codes. The ground motion records of one MS and three ASs were selected from the Wenchuan strong ground motion database to compose the seismic sequence. A series of peak ground acceleration (PGA) intensity levels were considered to scale the seismic sequence entirely for the simulation of sequential excitations. During the tests, typical global and local damage phenomena of the specimen were observed. Structural responses and dynamic properties of the specimen were monitored and calculated. An Aftershock Influence Ratio (AIR) defined as the ratio between the structural response due to an AS and that due to the corresponding MS was proposed to quantify the effects of ASs. Results show that AIR values are increased significantly as the growth of the accumulative damage of the specimen. Amongst the investigated structural response parameters, the absolute acceleration is impacted mostly by ASs with the corresponding AIR value as large as 85.2%, while the relative displacement is impacted least since the corresponding maximum AIR is only 27.9%. Moreover, at a given accumulative damage level of the specimen, the second AS (AS-II) has the largest effect on structural performance compared to others. This experimental investigation highlights the complex AS effects on structural performance since they are closely correlated to the accumulative damage of the structure mainly caused by MS, structural response parameters, and AS characteristics. It is thus necessary to well consider the AS effects in seismic performance evaluation and seismic design of the structures especially located in the sites with high seismicity.

Robustness quantification of reinforced concrete structures subjected to progressive collapse via the probability density evolution method

Robustness is the most comprehensive and acceptable index that describes the ability of structures to withstand progressive collapse induced by accidental extreme events such as impact, explosion and terrorist attacks. As found in the literature, several approaches have been proposed to quantify the robustness of a structure, e.g., approaches based on deterministic structural performance, failure probabilities (or the collapse reliabilities), and collapse risks. In this paper, the reliability-based approach is adopted to quantify the structural robustness of reinforced concrete (RC) structures subjected to progressive collapse since it is a trade-off between comprehensiveness and operability. An efficient calculation framework is developed based on the probability density evolution method (PDEM). Emphasis is placed on two aspects, i.e., the progressive collapse behavior modeling and the evaluation of the structural reliability. The static nonlinear pushdown method is employed to represent the progressive collapse capacity of the structures, and the force-based frame element is used to generate the finite element model. Then, the PDEM incorporated with the equivalent extreme value event is used to capture the reliability indices before and after progressive collapse. With the reliability indices, the robustness index can be easily computed. The developed framework is applied to two prototype RC frames designed in accordance with the Chinese design code. The reliability and robustness indices of the frames under different initial local damage scenarios (namely, removal of columns in typical pushdown method) are obtained, and the influences of the position of the initial damage scenarios on the robustness are also discussed.

Reliability of stability of single-layer latticed shells with spatially correlated initial geometric imperfection modeled using conditional autoregressive model

Latticed shells are extensively used for large-span structures. Their design is often governed by the global instability requirement stipulated in the Chinese design code for the specified gravity load and initial geometric imperfection (IGI). However, the reliability-basis for the recommended design requirement that a critical load factor of 2 need to be achieved is unknown. In the present study, it is proposed that the spatially varying IGI can be adequately modeled using the conditional autoregressive model. It is shown that this model is sufficiently flexible in modeling spatially varying correlated imperfection and can cope with irregular grid systems. By using this model for IGI and considering global instability, the probability distributions of the load capacity and the failure probabilities of spherical and cylindrical latticed shells designed according to the Chinese design code are evaluated. The evaluation is also carried out by representing the IGI shape using the spatially independent Gaussian model and the first eigen buckling mode (1EBM) that is recommended by the design code. It is shown that the use of the 1EBM to represent the IGI shape does not necessarily lead to conservative estimates of the failure probabilities as compared to those obtained by considering spatially varying stochastic imperfection shapes. The results shown that the estimated failure probability is sensitive to the assumed stochastic model for and standard deviation of the IGI at each joint of the latticed shells. Furthermore, the failure probability of the spherical latticed shell differs from that of the cylindrical latticed shell. The reliability analysis results also indicate that the use of a critical load factor of 2 implemented in the code for design of the latticed shell, in general, lead to an annual failure probability for global instability less than 10−5. A sensitivity analysis indicates that the code recommended critical load factor can be reduced to 1.75 while achieving a target reliability index often adopted for design code calibration.

Effect of spatially correlated initial geometric imperfection on reliability of spherical latticed shell considering global instability

Latticed shells are extensively used for large-span structures because of their good structural behaviour, lightweight and ease of construction. Their codified design is often governed by the global instability requirement for gravity load and specified shape and amplitude of maximum initial geometric imperfection (IGI). The reliability basis for the assigned shape and maximum IGI is unknown. In the present study, it is proposed that IGI is modelled using the simultaneous autoregressive model. It is shown that this model is flexible in modelling spatially varying correlated imperfection and can cope with irregular grid system. By using this model, the effect of the spatially correlated IGI on the probability distribution of the load capacity for global instability and the reliability of spherical latticed shell designed according to the Chinese design code is assessed. It is shown that the use of the prefixed shape of the IGI to assess the probability distribution of the load capacity is unconservative as compared to that by using spatially varying random imperfection. The shape of the probability distribution for the former differs from that for the latter. The reliability analysis results indicate that the use of a critical load factor of 2 implemented in the code leads to a failure probability less than about 10−6 for global instability if the specified maximum IGI defined in the code equals about two to three times the standard deviation of IGI. This failure probability becomes less than about 10−5 if a critical load factor of 1.5 is used for design. It is suggested that the code recommended critical load factor may be reduced to 1.5 while achieving target reliability index often adopted for design code calibration.

Shaking table tests on seismic behavior of ancient timber structure reinforced with CFRP sheet

This paper presents an experimental study on seismic behavior of ancient timber structure reinforced with Carbon Fiber Reinforced Polymers (CFRP) sheet. Based on a 1:2 scale one-bay and one-story ancient timber structure destroyed by the simulated earthquake, CFRP was used to reinforce the damaged ancient timber structure. Three seismic waves, including El Centro wave, Taft wave and Lanzhou wave, were input as the excitation wave. The displacement and acceleration response of the Column base, Column head, Pu-pai-fang, Bracket set and Eaves beam, the earthquake shear of structure and the internal force Sun-Mao node were analyzed quantitatively. Furthermore, the failure pattern of structure and dynamic property were analyzed qualitatively. The research shows that the friction and sliding of column base, rotation of semi-rigid tenon-mortise joint and sliding of Bracket set made the amplitude of seismic response of the structure greatly diminish with dynamic magnification factor about 1 which was much smaller than that of concrete structure about 2–4, and completely met the design requirements of Chinese code for seismic design of building. The distribution of the peak shear force of structure along the height appears at head or base of column, rather than must be the column base. The cumulative energy dissipation of three energy dissipation members reinforced with CFRP under different seismic conditions was calculated.

Depth Coherency Analysis for Strong Seismic Motions from KiK-Net

ABSTRACT Due to the limited number of seismic records in the soil and inefficient use of one-dimensional wave theory in the estimation of vertical components for seismic waves, this paper studies depth coherency (coherency between the surface seismic waves and that at depth) in order to describe seismic acceleration at different depths based on surface seismic acceleration signals. In this study, the authors utilized data from the KiK network to investigate the variability of seismic ground motions with depth and obtain a model to simulate coherency of depth-dependent ground motions. Furthermore, by using the methodology described in the Chinese Code for the Seismic Design of Buildings, the authors categorized a number of test locations based on the depth and shear velocity of the soil cover. Four different types of sites were defined and both the horizontal and vertical components of ground motion from strong motion seismometers were analyzed. The results show that there is no significant dependence between the estimated coherencies from different earthquake magnitudes or epicentral distance (less than 200 km). Moreover, the behavior of depth coherency is site-dependent and there are notable differences between horizontal and vertical depth coherency. In addition, existing spatial coherency models may not provide a satisfactory estimate of the variation of depth coherency.

Investigation on steel-concrete composite frame in Chinese traditional style buildings by pseudo-dynamic test

A series of pseudo-dynamic tests of a 1/2-scale 1-story 3-bay Chinese traditional style frame using steel - concrete composite columns was performed. During the test, the input ground motions were chosen from El Centro wave, Taft wave and Lanzhou wave. And peak ground acceleration (PGA) were 35 gal (minor earthquake of 7 degrees), 100 gal (precautionary earthquake of 7 degrees), 220 gal (major earthquake of 7 degrees) and 400 gal (major earthquake of 8 degrees), respectively. The failure modes, displacement and acceleration time history curves, hysteretic loops of restoring force- displacement, energy dissipation capacity and deformability, inter - story drift ratio of the test model were analyzed. It is shown that the typical failure modes of the model are concrete cracking at the connection between hypostyle column and penetrating tie as well as yield of longitudinal reinforcement of hypostyle column and peristyle column. And also, the model has better plastic deformation capacity. With a larger PGA, natural frequencies and dynamic amplification factors decreased, but its energy dissipation capacity increased. The energy dissipation of the model subjected to El Centro wave was largest with the same PGA. Based on the experimental results, the modal analysis and dynamic elasto-plastic analysis of the test model was performed using finite element software SAP2000. The results showed that under the action of horizontal earthquake, the 1st mode was translation of the model, and the plastic hinges of the model first formed on the ends of penetrating tie and successively developed at the root of hypostyle column, peristyle column, CRST-2 and CRST-3 and CRST-1 and CRST-4. And the inter-story drift ratios of the model subjected to 700 gal El Centro was close to the limited value in Chinese Code for Seismic Design of Buildings (GB50011-2010), indicating that the frame had a higher safety margin.

TESTS ON LOAD-CARRYING BEHAVIOR OF STAINLESS STEEL BOLTED T-STUB CONNECTIONS

A total of 14 stainless steel bolted T-stubs were tested under monotonic loading. The ultimate strength, failure modes and prying forces of the test specimens were obtained. The effects of the key parameters including the flange thickness, flange material grade, bolt diameter and bolt preloading were analyzed. It was revealed that the introduction of bolt preloading had little effect on the ultimate strength and failure mode, but resulted in increased initial stiffness for the T-stub specimens. The failure mode of the T-stub connections depended on both the tensile strength of the bolt and the flexural strength of the flange. The prying forces increased gradually with reduced flange thickness and bolt diameters, while the prying forces corresponding to the ultimate strength were not influenced by the bolt preloading. The test results were further compared with the strength predicted by the existing European, American and Chinese design codes. It was found that the existing design provisions were generally conservative for stainless steel bolted T-stub connections, among which the American code provided relatively better predictions. It may be attributed to the use of material tensile strength instead of yield strength.

Experimental study of cold-drawn duplex stainless steel circular tubes under axial compression

Cold-drawing is one of the typical cold-forming techniques in producing stainless steel circular hollow sections (CHS). Compared with cold-rolling, cold-drawing can produce large scale stainless steel tubes which have wide applications in highly corrosive environment. Nevertheless, few researches have been carried out on the duplex stainless steel CHS columns. In this paper, cold-drawn duplex S22053 stainless steel CHS of three types of cross-sections were tested, including 8 material tensile coupon tests, 6 axially compressed stub column tests and 7 axially compressed long column tests. The material stress-strain curves of the cold-drawn CHS tubes, ultimate loads and failure modes of the stub and long columns were obtained. It has been revealed that material properties of cold-drawn stainless steel CHS tubes are close to those of the virgin plate in the annealed state. Moreover, all the stub columns show local buckling in “elephant foot” mode, while all the long columns undergo overall flexural buckling, among which a long column specimen with the nominal length of 700 mm（CHS-700） shows local buckling after the peak load due to the interaction of axial compression and second-order bending moment. Furthermore, comparing the test values with the predicted values based on the European, American, Australian/New Zealand and Chinese design codes, and the calculation methods available in literatures, it is concluded that the predicted values of the stub columns and the long columns with relatively large member slenderness are all lower than the test values, while the predicted values using the design methods except that in the Chinese design code are higher than the test values for the long columns with relatively small member slenderness. Chinese design code could provide safety predictions for cold-drawn duplex stainless steel CHS columns.

Probabilistic Seismic Response Analysis on Continuous Bridges Under Near-Fault Ground Motions

This paper focuses on the pulse-like near-fault ground motion, developing a probabilistic seismic demand model to estimate the seismic response of regular continuous bridges. A three-span bridge with continuous deck is taken as the basic case to establish 25 representative samples by changing the geometrical parameters and modeled with OpenSees software. The ground motions of both near fault and far fault are selected from PEER NGA strong ground motion database. The seismic response of the bridge is evaluated using the drift ratio at the top of the pier. A series of nonlinear dynamic time history analysis is carried out to compare the damage obtained with near-fault and far-fault ground motions for three different site conditions. Subsequently, a sensitivity analysis is performed on the design parameters according to the orthogonal experimental design methodology. After selecting the Housner intensity as the most suitable intensity measure and drift ratio as the engineering demand parameter, the probabilistic seismic demand model is established for the near-fault earthquake on the site II condition which is classified by Chinese design code. The results show that the near-fault earthquake can lead to more serious damage with respect to regular bridges and that the probabilistic seismic demand model allows for a quick evaluation of the seismic behavior of regular continuous bridges under pulse-like near-fault earthquake.

Shear Capacity of Open Sandwich Steel Plate‐Concrete Composite Slab: Experimental and Analytical Studies

Considering that the fixed crack model by default of the general finite element software was unable to simulate the shear softening behavior of concrete in the actual situation, a rotational crack model based on the modified compression field theory developed by UMAT (user material) of ABAQUS software was proposed and applied to the nonlinear analysis, and a numerical simulated model for the steel‐concrete composite slab was built for shear analysis. Experimental studies and numerical analyses were used to investigate the shear load‐carrying capacity, deformation, and crack development in steel plate‐concrete composite slab, as well as the effects of the shear span ratio and shear stud spacing on the shear performance and the contribution of the steel plate and the concrete to the shear performance. Shear capacity tests were conducted on three open sandwich steel plate‐concrete composite slabs and one plain concrete slab without a steel plate. The results indicated that the shear‐compression failure mode occurred primarily in the steel plate‐concrete composite slab and that the steel plate sustained more than 50% of the total shear force. Because of the combination effect of steel plate, the actual shear force sustained by the concrete in the composite slab was 1.27 to 2.22 times greater than that of the calculated value through the Chinese Design Code for Concrete Structures (GB 50010‐2010). Furthermore, the shear capacity of the specimen increases by 37% as the shear stud spacing decreases from 250 mm to 150 mm. By comparing the shear capacity, the overall process of load deformation development, and the failure mode, it was shown that the simulation results corresponded with the experimental results. Furthermore, the numerical simulation model was applied to analyze the influence of some factors on composite slab, and a formula of shear bearing capacity of slab was obtained. The results of the formula agreed with the test result, which could provide references to the design and application of steel plate‐concrete composite slab.

A Comparative Study on Seismic Performance of Precast Shear Walls Designed with Different Variables

In order to assess the behavior of the precast shear walls with three different variables and promote the application of the new types of precast shear walls in structures, six precast shear walls with boundary elements designed based on Chinese code for design of concrete structures were tested under quasi-static cyclic loading. The three variables are reinforcement type, horizontal connection and vertical connection. In particular, there are three types of reinforcement, which are uniform, 3 × 3 and 4 × 4; three types of horizontal connection, which are dovetail joint, T-shape slot and rough surface; two types of vertical connection, which are welding and slurry sitting. Tests results indicate that the failure mode of specimens SW-1 through SW-5 was diagonal tension failure and failure mode of specimen SW-6 was shear sliding; the three variables have effect on peak load, drift ratios and ductility; the combination of reinforcement type “4 × 4”, dovetail joint and welding make an improvement on peak load, ductility and energy dissipation; while the T-shape slot is not applicative preferentially in horizontal connection and the slurry sitting vertical connection type is not recommended in mid-rise buildings.

Experimental study on seismic performance of L‐shaped insulated concrete sandwich shear wall with a horizontal seam

SummaryA series of new L‐shaped insulated concrete sandwich shear walls integrated with heat preservation function are tested for its seismic performance. Those specimens, partially excavated and filled with insulation materials, are made up of three precast specimens and one cast‐in‐situ specimen as a control group. For the three precast specimens, the vertical distributed reinforcements are equivalently spliced to the bottom beam by grouting sleeves arranged along the centerline of the wall, whereas for the compared specimen, they are directly cast‐in‐situ anchored. These specimens are tested under low frequency cyclic loading. The failure mode, yielding load and displacement, skeleton curve, energy dissipation, stiffness degradation, ductility, and so forth, are recorded and analyzed. The result shows that the precast specimens have similar bearing capacity and much better deformation capacity and ductility than that of the control group in this experiment. This indicates that the seismic performance of the proposed L‐shaped insulated concrete sandwich shear wall is desirable and generally meets the requirements of both function and safety, thus can be used as structural elements in practice. The methods in Chinese design code and American Concrete Institute code are adopted to calculate the ultimate shear capacity of this precast insulation shear wall, and it is found that the tested result is larger than the calculated one, indicating the calculation method is reliable.

Strength of duplex stainless steel fillet welded connections

Standard uniaxial tests were conducted on round bar specimens made of stainless steel and the corresponding weld metal. The stress-strain curves of both base metal and the corresponding weld metal were obtained. The constitutive relationship for base metal and the corresponding weld metal were calibrated against the test results and were taken into consideration for further finite element analysis on stainless steel fillet welded connections. Six transverse fillet welded connections and five longitudinal fillet welded connections were tested to investigate the strength, deformation, and fracture angle of stainless steel fillet weld connections. According to the test results, the average angle of stainless steel transverse fillet weld was 29°; the average angle of stainless steel longitudinal fillet weld connection was 46°. The ultimate strength for a transverse fillet weld connection was 1.5 times than that of a longitudinal fillet weld. Relevant numerical models using ANSYS were calibrated against experimental results. Further parametric studies were conducted to investigate the effect of weld length and weld size on the strength of stainless steel fillet welded connections. Finally, both the experimental and numerical results were compared with the current design provisions. The conservatism of the European, American, and Chinese design codes was discussed. A revised prediction of fillet weld strength was proposed based on the strength of the longitudinal fillet weld strength.

A three-dimensional elasto-plastic dynamic response procedure for concrete-faced rockfill dams

Equivalent linear dynamic analysis is the primary method of analysis for concrete-faced rockfill dams during earthquake. However, this method cannot be directly used to estimate permanent deformation during earthquake, which is important to evaluate the dynamic safety of concrete-faced rockfill dams. To bridge this gap, an elasto-plastic dynamic response procedure based on finite element method is presented to estimate the construction, impoundment, and dynamic characteristics of concrete-faced rockfill dams. This procedure involves a generalized plasticity model for rockfill materials and an ideal elasto-plastic model for interface between concrete face slab and rockfill material. The construction, impounding process, and seismic behavior of a 150-m-tall concrete-faced rockfill dam were simulated using seismic motion based on Chinese code for seismic design of hydraulic structures of hydropower project with the peak ground acceleration of 0.3 g as an excitation to validate the procedure. On the basis of the numerical simulation results of the step-by-step construction, reservoir impoundment and seismic response of a concrete-faced rockfill dam, dam settlement, joint deformation, stress, and deformation of slab were analyzed. The results indicate that the dam settlement and deformation of joint can be directly obtained by the procedure during earthquake. The construction, impoundment, and seismic analysis could be considered in one procedure.

Experimental and Numerical Studies on Seismic Behavior of Q460 High Strength Steel Reinforced Concrete Column

High strength steel reinforced concrete (HSRC) column refers to steel reinforced concrete column using high strength steel with its yield strength over 420MPa. So far, research on seismic behavior of HSRC columns is limited. This paper presents experimental and numerical studies on seismic behavior of HSRC columns. Two Q460 high strength steel reinforced concrete columns have been tested under low cyclic loading with constant axial compression ratio of 0.3. Flexural failure is observed in the test. From the hysteresis curves, the specimens exhibit good ductility and satisfactory energy dissipation capacity. Displacement ductility factors are larger than 2. When load descends to 85% of the peak load, the ultimate drift ratios of two specimens are 1/29 and 1/26 respectively, which meet the requirements of Chinese Seismic Design code (GB 50011). To study the seismic behavior of HSRC columns more comprehensively, a numerical model has been established for simulating the experiment using OpenSees, which adopts nonlinear beam-column element and fiber model. The numerical result fits the test data well, which validates the effectiveness of numerical model. Parametric study is then carried out to further investigate the seismic behavior of HSRC columns.

Fragility curves for steel-concrete hybrid tall buildings

Fragility curves of steel-concrete hybrid tall buildings designed according to the current Chinese seismic design code were derived by analytical methods, taking into account the uncertainty of earthquake ground motions. In total, 45 analytical models were analysed considering all combinations of three design parameters, i.e., seismic protection intensity, site soil type and design group. On the basis of a large number of nonlinear time history analyses, fragility curves were derived reflecting exceeding probabilities corresponding to each performance level. The influence of different engineering demand parameters (EDPs) and design parameters on fragility curves was analysed. The result showed that fragility curves based on different EDPs varied significantly, indicating that different structural components played different roles in seismic performance of the structure. While seismic protection intensity had little impact on seismic vulnerability, structures tended to be more vulnerable on the site with softer site soils and longer characteristic periods.