Abstract:Bresler-Scordlis beam was numerically analyzed to verify a finite element model proposed by ATENA. The simulated damage process and failure mode of Bresler-Scordlis beam and the experiment result are in good agreement. Then, 133 beams of Kani test were analyzed with the verified model. The ultimate load of simulated beams agrees well with the experiment data. From the further analysis of the simulation results of Kani beams, it can be found that the shear capacity contribution of arch action grows and the shear capacity contribution of teeth action reduces as the shear-span ratio increases. The nominal ultimate shear stress of the beams decreases with the increase of shear-span ratio. The curve turns obviously at the shear-span ratio of 2.5. The degree of the reduction before the turning point is larger than that after the point. When the shear-span ratio is larger than 2.5, the shear resistance of the beams with similar factors reduces slowly or even almost remains constant. However, the length of the shear span increases due to the growth of shear-span ratio. As a result, the maximum moment at failure increases, as well as the ratio of the moment and full flexural capacity. Hence, "The valley of shear failure" proposed by Kani has a rising branch as the shear-span ratio is greater than 2.5.

Abstract:One high strength concrete short beam and two PE-ECC short beams were designed and fabricated, the shear tests of these short beams were carried out, and the shear capacity calculation of these short beams were done by using the strut-and-tie model method, the finite element method and the method in the current Chinese code. The results have indicated that shear failure has occurred in the three short beams, but the high strength concrete short beam has undergone shear-compression failure, and the PE-ECC short beams have undergone flexure-shear failure. The PE-ECC short beams have higher value of cracking load and ultimate load and exhibit better shear ductility, compared with the high strength concrete short beam. Meanwhile, the strut-and-tie model method and the finite element method can reasonably predict the shear capacity of these short beams，and the code method seem to be too conservative.

Abstract:This paper developed an artificial neural network (ANN) based method for the prediction of the yield performance of rectangular RC columns. In this method, the inputs of ANN were determined on the basis of the empirical studies of the impact factors of the yield performance of RC columns. The sensitivity analysis of the yield performance of RC columns was also investigated to validate the reasonability of the inputs selection of ANN. In order to demonstrate the feasibility and effectiveness of the proposed method, the ANN models were applied to predict the yield performance of rectangular RC columns by using 210 sets of experiment data provided by PEER, Furthermore, the predicted results were compared with empirical model results. Comparative analysis has shown that the prediction degree of agreement with the experiment results of ANN models is much better than that of other empirical prediction models. Also, the result reveals that the proposed method provides a new way for accurately estimating structural performance under earthquake with data scarcity.

Abstract:Through the tests of new horizontal-hole hollow concrete block and masonry on compressive strength when the concrete compressive strength grade is between C25~C45, the compressive strength relationships were studied among the concrete, block and masonry. The experiment results show that the ratio of the crack load to the break load of the block and masonry is 84%~90% and 80%~94% respectively; the compressive strength of the block and masonry increases by 13%~23% and 13%~30%, respectively with the enhancement of concrete compressive strength grade, and the increase slows down gradually; and the average compressive strength formula of the block is derived. It turns out that the compressive strength formula of the masonry recommended by the Code for Design of Masonry Structures (GB 50003-2011) is not applicable for the masonry researched in this paper. The compressive strength formula of the new horizontal-hole hollow concrete block masonry was proposed.

Abstract:This paper studied the mechanical properties of circular concrete-filled steel tubular (CFT) stub columns with local compression, conducted an experimental study of the local compression of 12 circular CFT stub columns and compared the influence of concrete strength grade and local compression area ratio on ultimate bearing capacity. It is found that the ultimate bearing capacity increases with the increase of concrete strength grade and the decrease of area ratio. Then, based on the reasonable material constitutive relation, it established a shell-solid 3D finite element model of circular CFT stub columns with local compression by using ABAQUS. And on the basis of the experiment verification, it explored the influence of local compression area ratio, steel ratio, and strength of steel and concrete on ultimate bearing capacity. Furthermore, this paper presented practical computational methods for the local compression bearing capacity of CFT stub columns with circular section by fitting analysis. It then compared the 47 groups of circular CFT stub columns, which combined the formula results, and calculation formula by other scholars, with the finite calculation results. The results show that the formula results are in good agreement with the experiment results.

Abstract:In order to study the seismic performance of new hybrid precast concrete shear wall (NHPW), the low frequency cyclic loading experiment was carried out on one cast-in-situ and three NHPW specimens with different prestress forces. Compared with the cast-in-situ specimen, the anti-cracking ability, capacity strength and stiffness of NHPW specimens have been obviously improved, the displacement ductility remains similar, and the energy-dissipating capacity is lowered within later load stage. Meanwhile, along with the increase of the prestress force, the specimen stiffness and crack load have been enhanced, residual displacement decreases and the capacity property remains steady. The proposed method for predicting the ultimate stress of unbounded posttensioned tendons possesses high accuracy and the strength capacity design method according to available standard can ensure sufficient safety.

Abstract:This paper studied the effect of weight limit signs on restricting truck drivers' behavior based on the results from a questionnaire survey conducted among truck drivers in a province in China. Based on the statistic properties of the field measured traffic flows, models for random traffic flows were developed by using the Monte-Carlo method while taking into consideration the effect of the weight limit signs on restricting the drivers' behavior. Taking a weight limit of 55 t for example, the load effect for the midspan bending moment and end shear for simply-supported beam bridges under the generated random traffic flows were studied by using the method for analyzing the load effect provided in the Unified Standard for Reliability Design of Highway Engineering Structures. A parametric study was also conducted to study the effect of the average daily vehicle traffic, conditional restriction level, and bridge span length. The calculated load effect under the generated random traffic flow was compared with that calculated by using the design load given in the current Chinese bridge design code. The results show that: 1) the weight limit sign can effectively reduce the maximum vehicle load effect and insure the bridge safety and reliability only when the truck drivers strictly obey the weight limit regulation; and 2) the design vehicle load in the current Chinese bridge code may have underestimated the real traffic loads, especially for short-span bridges, to which special attention should be given.

Abstract:To study the shear mechanical property of corrugated steel webs, four H-shaped steel beams with trapezoidal corrugated steel webs were designed and tested to obtain the shear behavior of corrugated steel webs. In addition, the elastic bucking strength of the corrugated steel webs was discussed according to statistical data of their dimensions for the as-built PC composite box girders around the world. Then, we proposed the simplified computational formulae and the corresponding scope. Furthermore, considering that the local elastic bucking strength is less than global elastic bucking strength, the formulae for calculating the nonlinear shear strength presented by Yi and NIE were studied on the basis of some test results, and the test results were verified by comparing the analysis results of ANSYS software. It is concluded that the shear force is mainly borne by the corrugated steel webs and the distribution of the shear stress along the height of the web is uniform. And the shear capacity of corrugated steel webs will be greatly affected by the initial imperfections. What is more, the proposed computational formulae for the elastic bucking strength and nonlinear shear strength are in perfect accordance with the model test results and the numerical analysis results, so they can provide a reference for practical structural design.

Abstract:In order to accurately simulate the inlet boundary conditions of turbulence information of Large Eddy Simulation (LES), the fluctuating time-history data satisfying the target wind field were simulated with the weighted amplitude wave superposition (WAWS) considering the integral scale, power spectrum, turbulence intensity and wind velocity profile. The fluctuating time-history data were given to the inlet boundary of LES by the secondary development of the commercial software FLUENT. Consequently, the fluctuating information of the Large Eddy Simulation was obtained. The two numerical models were established on the basis of the experiment data in the wind tunnel. The first was the flow field without any obstacles in which the fluctuating time-history data simulated by WAWS method were the inlet boundary condition. The second was the flow field with spires and roughness element model in accordance with those in the wind tunnel, in which the mean wind velocity was given to the inlet boundary and the wind turbulences were generated by the spires and roughness elements. The results show that fluctuating wind field based on the WAWS method can be the inlet boundary for the LES and provides a reference for the investigation of the inlet boundary conditions of LES.

Abstract:This paper was concerned with the unsteady characteristics of the conical vortex on a flat roof on the basis of numerical results by large eddy simulation (LES) when an approaching flow attacks at about 45 degrees against the wall. The results indicate that the large eddy simulation (LES) can give fairly good results, compared with the experiment pressure data of the AIJ flat roof model and other wind tunnel tests. Based on the Q criterion, this paper presented the flow visualization of conical vortices on the roof. By analyzing the mean and fluctuating pressure coefficients on the roof, it is observed that the strong suction acts on near leading edge on the flat roof of the building. The strong suction is caused by a pair of conical vortices whose strength is unbalanced in any time. When the strength of one vortex recedes, the vortex on the other side is strengthened. By adding splitter plates and parapets, the LES results show that the switching of conical vortices may have inseparable relations with the interaction of vortices formed in the wake shed from the sidewalls of the building. Additionally, the parapets can mitigate the high corner suctions on the roof and lift the position of vortex core, while the dimension of the conical vortex is greater with the higher parapets.

Abstract:Taking a typical 500kV full combined substation framework as the background, the shape factor of the wind load and the dynamic response factor of this structure were investigated by combining wind tunnel tests and finite element calculation analysis. Three single beam models and a full combined framework model were produced at 1∶11 and 1∶32 model scale, respectively. Then a series of experiments were conducted to test the shape factors. Finally, based on the wind tunnel results, the wind-induced response analysis of the full combined substation framework was done, and the dynamic response factors were obtained. The results show that the test values of the shape factors of beams A, B, and C are 2.23, 2.35 and 2.18, which is 8%, 14% and 7% larger than the corresponding values stipulated in load code for the design of building structures and the technical code for the design of substation buildings and structures. For a 2% damping ratio, the dynamic response factors of the beams at 20m, 26m and 34m are 1.60, 1.80 and 1.58, respectively. And those are 7%, 6% and 5% larger than the dynamic response factors prescribed in the technical code for the design of substation buildings and structures. This indicates that the design loads specified in current domestic provisions for this structure are non-conservative.

Abstract:Wind-induced ice-shedding makes transmission-line tower system produce complex dynamic responses. This paper built a finite element model of a three-span transmission-line system. When galloping occurs in mid-span conductors, with or without ice-shedding, the dynamic responses of the transmission-line tower system were analyzed through numerical experiment, and the differences of the two load cases under different wind speeds were also studied. Besides, this paper also analyzed the dynamic characteristics of the system. In the model, the initial deformation and stress of the conductors is taken into account. The results show that the unbalanced tension of the tower head and the transverse conductor-amplitude of adjacent spans get larger with the increase of wind speed. The transverse vibration frequency of adjacent-span conductors led by ice-shedding increases dramatically, and the vertical rebound height decreases relatively. The vertical rebound height and transverse amplitude of the mid-span increase by about 73.9% and 57.7% respectively, to which special attention should be paid in the design of transmission lines.

Abstract:The reinforcement effect of the high performance ferro-cement laminates (HPFL) was investigated as composite covers of precast concrete hollow slab on the integrity of precast concrete hollow slabs by three conditions under simulated earthquakes action. The results have shown that slabs and composite covers have not debonded after the destruction of the supporting wall at different locations, even two hollow slabs cantilevered at lateral. As the composite cover of precast hollow plate, HPFL can effectively improve the integrity of precast hollow floor slab, make hollow slab continuous at two vertical directions of horizontal direction, and any stiffness of the horizontal components in this plane approaches infinity, so that structural integrity and earthquake resistant performance of hollow slabs are guaranteed.

Abstract:In order to understand the relation between the superstructure stiffness and uneven settlement in bottom frame masonry housing, ANSYS was used to build the 3-D model of a real house. Changing superstructure elasticity modulus, three different conditions were conducted. Through subsidence of columns bottom analysis, it was found that the subsidence of columns bottom had a certain relationship with superstructure elasticity modulus. The decrease of uneven settlement is obvious by improving the stiffness of the wall of the second floor, but it is not the case with other floors.

Abstract:The development of the video camera with high speed and high resolution makes it possible to conduct photogrammetry-based non-contact displacement measurement. This paper presented the estimations of the tension force of a cable by using the moving target image tracking technologies. A video camera was employed to capture the vibration image sequences of single or multiple targets installed along the cable. The background difference method was used to detect the moving targets, and then, the Kalman filter was conducted to track the moving target, from which the vibration response of the cable can be attained to extract the cable force in the general frequency-based method. The experiment test results reveal that there is a small error between the results measured from photogrammetry and those from accelerometers. The photogrammetry method has the potential of becoming an effective complement of the non-contact testing.

Abstract:By conducting indoor comparative trial, we studied the impact of the radiant cooling combined with wall-attached-jet system on indoor thermal environment, along with the effect of this combined system on preventing condensation on the ceiling of radiant cooling panel. The result shows that, compared with pure radiant cooling system, those integrated with wall-attached-jet system possess the advantages of a faster cooling speed and a wider cooling magnitude. Meanwhile, considering indoor thermal environment, the composite system has a lower wall temperature, indoor air temperature and humidity. It is concluded that the method of adopting both radiant cooling and wall-attached-jet system simultaneously is more effective in decreasing the dew-point temperature around the radiant cooling panel and protecting the panel from condensation. Moreover, at this time, the refrigeration performance of the radiant cooling panel is greatly enhanced.

Abstract:To study the heat rejection law of office building air-conditioning refrigeration system with a large heat rejection per unit building area, one office building in Shenzhen and three office buildings in Beijing in the center of the city were selected as the main research objects, and the heat rejection from air-conditioning refrigeration system through cooling tower was discussed in two forms:sensible heat and latent heat in the field measurement method. This field study results show that the total heat rejection from building air-conditioning refrigeration system per unit building area has a daily average value in the range of 85~106 W/m2, where the sensible and latent heat share the proportion of 1%~5% and 95%~98.85% respectively. It indicates that office building air-conditioning refrigeration system releasing the condensing heat into the outdoor environment through cooling tower is mainly in the form of latent heat, which has a significant effect on the building surrounding humidity environment. Finally, higher temperature and humid outdoor climatic conditions are not conducive to the heat and moisture rejection from the building air-conditioning refrigeration system.

Abstract:This paper studied the economic design of the unilateral template and support system for the current use in underground engineering cast-in-place concrete external wall and unilateral template system as the internal model of exterior wall construction. The corresponding force mechanic model was established through the analysis of the working conditions and stress state of the cast-in-place single-side concrete formwork templates and the support system. Furthermore, an economical ultimate state design method was proposed to make full use of the material performance under the condition of meeting the functional requirements. The economic arrangement distances of the base and the secondary beam and support system as well as anchor bolt diameter were analyzed. The effect of saving material and reducing the construction cost were obtained after practical engineering computing applications.