Advanced Materials Research Vols. 250-253

Abstract: Ground anchors have been very practical in a wide range of geotechnical structures. Good bond properties at the anchor-mortar and mortar-rock interfaces can ensure transmitting an applied tensile load to a load bearing structure efficiently. The bond performance between the mortar and rock is necessary to be studied. A push-out test of mortar from rock block can be used to analyze the interfacial properties between the two materials. In this paper, an analytical model is proposed to determine the push-out capacity of mortar from rock block. Based on the deformation compatibility at the interface, the compressive stress in the mortar and the interfacial shear stress at the mortar-rock interface are formulated at different loading stages. By modeling interfacial debonding as an interfacial shear crack, the push-out load is then expressed as a function of the interfacial crack length. In virtue of the Lagrange Multiplier Method, the maximum push-out load is determined. The validity of the proposed model is verified with the experimental results. It can be concluded that if the interfacial parameters at the mortar-rock interface are obtained, the push-out capacity of mortar from rock block can be accurately determined using the proposed model. The proposed solution in this paper would provide a good theoretical basis in evaluating the stability of ground anchors in practice.

Abstract: Low-cycle cyclic loading tests were carried out on seven reinforced concrete shear wall specimens with different design parameters to investigate the damage behavior under earthquakes. The damage features including the damage process, deformations, the maximum crack width and the corresponding residue crack width at different damage state were recorded. According to the experimental data, the influence of axial compressive load ratio, stirrup ratio of the boundary column and cross-section shape on the ductility, carrying capacity, deformation characteristic and seismic damage is analyzed. With the axial compressive load ratio increasing, the carrying capacity and shear effect increase while the ductility and residual crack ratio decrease. With the deformation and damage increasing, the shear effect increases. The shear walls with I-shaped cross-section display more shear effect than those with the cross-section of “—” and “T” shape.

Abstract: The experimental study on shear capacity of 24 broad-limb special-shaped columns subjected to low cyclic loading were executed. The characteristic of hysteretic curve and skeleton curve were analyzed. The influences of the lateral bevel loads and the limb’s width-thickness ratio on the shear strength of the T-shaped and L-shaped broad-limb special-shaped columns were studied. The application of the shear formula in the current code for the broad-limb special-shaped columns was verified. It is shown that using the formula to calculate the shear strength of broad-limb special-shaped columns is safe from the results.

Abstract: This paper is an analytical study of the planning techniques of the new residential areas in Beijing’s suburbs at the turn of the 21^st century, including the scale, structure, road network, green system and public building arrangements of a housing program. Its purpose is to reexamine the assumptions for the planning techniques of modern residential areas, recheck the legitimacy of these techniques, and reconsider residential areas as a proper residential model for modern Beijing. The paper evaluates three issues related to the modern residential areas: the controversies associated with super residential areas, the relationship between pedestrians and automobiles, and urbanization and mix-use communities.

Abstract: Autoclaved lightweight concrete (ALC) block infills are used widely for steel residential building system in China; the authors of this paper brought forward a kind of macro finite element (FE) model of ALC block infills of steel frames on the basis of experimental study. Furthermore the hysteresis model of the strut element of infill was established. At last the validity of the strut element was verified by comparison theory analysis results with experiment ones. The analysis method and theory of this paper can be applied to other kind of infills after being revised properly.

Abstract: By the Xi'an Beilin Museum of Historic Buildings Survey durability of brick masonry and brick surface material X-ray diffraction analysis showed that the durability of historic buildings degradation of common brick, Environmental conditions and construction materials with different degree of degradation is a clear significant difference. According to the survey results, analysis of the durability of brick masonry deterioration of historic buildings causes and influencing factors, such as the future durability of brick masonry buildings to provide a reliable basis for restoration.

Abstract: A series of dynamic triaxial tests which used saturated samples of three different particle size distribution anti-filter materials in high earth-rock dams have been investigated for the development of dynamic pore-water pressure. The experimental results show that the relationship between μ_d/σ'_m and N/N_f in the same consolidation condition are unitary if we applied different dynamic stress to the same particle size distribution anti-filter material. Besides, if N/N_f <0.6, the value of μ_d/σ'_m increases quickly. The increase rate of μ_d/σ'_m will be slower if N/N_f≥0.6. When the consolidation stress ratio is invariant, the change of ambient pressure has no effect on relationship between μ_d/σ'_m and N/N_f. When the gradation and ambient pressure of anti-filter material are changeless, the change of consolidation stress ratio has obvious effects on relationship between μ_d/σ'_m and N/N_f. When the value of consolidation stress ratio is increase, the number of dynamic pore-water pressure ratio obviously decrease. When the consolidation condition of anti-filter material is changeless, the change of anti-filter material’s grade doesn’t have obvious effects on the relationship between μ_d/σ'_m and N/N_f.

Abstract: Most of the Chinese scholars have simplified the relationship between the client and the agent-construction enterprise as a single-task principal-agent problem, which has ignored the important fact of multitasks, such as progress, quality and cost. In this paper, a multi-task principal-agent model with three tasks, i.e. progress, quality and cost, is constructed to analyze the optimal incentive contractual conditions and multi-task incentive equilibrium mechanism of the agent-construction enterprise, which can provide theoretical basis for the regulatory policy of government investment project.

Abstract: It’s important to identify structural modal parameter in time and accurately for structural health monitoring and damage identification. Wavelet analysis is one of the various kinds of identification methods, which has been used in linear and nonlinear system response data since it can decompose signals simultaneously both in time-domain and frequency-domain with adaptive windows. In this paper, taking Bariba Bridge as an example, the modal analysis results obtained from the finite element model are compared with those estimated from the wavelet transform method. Good coincidence of results can be observed, which demonstrates that the built-up finite element model reflects the bridge’s real dynamic properties, and can serve as a baseline model for its dynamic response analysis under complicated excitations, long-term health monitoring and structural service state assessment.

Abstract: In recent years, the magnetorheological (MR) fluid damper-based semiactive control systems have received considerable attention for protecting structures against natural hazards such as strong earthquakes and high winds. In this paper, an improved modal controller integrated with a Kalman-filter observer is proposed for vibration control of spatial structures. The proposed modal controller can reduce the dimension of the control equation and thus can relieve the calculation burden greatly. In the proposed control system, a Kalman-filter observer, which estimates the full controlled modal states from local accelerometer outputs, is designed for rendering the controller to be more applicable to real spatial structures with a large number of degrees of freedom (DOFs). A numerical example of a lattice roof structure installed with MR dampers is presented. The effectiveness of the controller is evaluated under both Tianjin and El Centro earthquake excitations. The simulation results demonstrate not only its effectiveness of reducing vibration of spatial structure, but also its adaptability for versatile loading conditions.