Applied Mechanics and Materials Vols. 479-480

Abstract: Pile-to-pilecap connection such as in integral abutment bridges is vulnerable to lateral loads as well as seismic loads. This connection may govern the bridge strength and performance against various lateral loads. However, previous researches have merely focused on the connection between pile and pilecap. Preliminary study has investigated possible crack patterns between concrete pilecap and steel HP pile using finite element analyses. It was found that the crack patterns are sensitive to the boundary conditions specified in the simulation. The reinforcement detail specified in PennDOT DM4 was barely effective in controlling crack growing but spiral rebar was proved to be effective in delaying crack growth as well as absorbing energy capacity. In this study, two types of connection details of (1) HSS tube type and (2) removed flange type were investigated in terms of crack control. The connection with a HSS tube exhibited to be effective in prevention of crack propagations from the surface of the bottom pilecap. However, second crack was initiated from the corner region of the tube after first crack was arrested; resulting in lower energy absorption capacity compared to both spiral and removed flange details. In the connection with removed flange, concrete crack initiations were mitigated or delayed successfully.

Abstract: In civil engineering, the long-term service life of buildings as environmental measures is one of important performances being comparable to structure and fire safety, and it is demanded to improve durability of materials in building construction. This improvement of material durability is highly associating with lifetime of building, and so as not to reach the limit state of building components. It is imperative to determine a specific means and method in order to identify the surrounding environment on the deteriorating effect for building components and materials, as well as predicting a process of degradation phenomena and the limit state of buildings. As part of building materials, polymeric materials become widespread in civil engineering because of taking advantage of excellent property, such as lightweight, high corrosion resistance, and good formability. However, we should look ahead the lifecycle cost in order to have effective application of this material, so it is necessary to understand the lifecycle of such material. In weathering, outdoor weathering test is the surest way to clarify exactly how a material, component, or products degrade by environmental stresses in an acceptable timeframe, but it usually takes few years to decades to obtain a useful or referable result. Meanwhile, accelerated weathering test methods have been proposed as a method to obtain the results in a short period of time than outdoor weathering test. However, the method of estimating a material durability in the actual environment from these obtained data has not yet been established.In this section, it would be showing some attentions for comparison of the results from outdoor and accelerated weathering test. Then the need for investigating weatherability of polymeric materials through physicochemical analysis are emphasized to improve the relevance and precision of durability under field and laboratory weathering test. Lastly, introducing the design of accelerated weathering method based on natural weathering characteristics.

Abstract: High-rise housing buildings were first built approximately 45 years ago in Japan and these buildings currently are old and deteriorated facing the need of repair. In this study, I present a practical case - Kajima Corporation Minaminagasaki Dormitory, one of the oldest high-rise reinforced concrete buildings in Japan. The purpose of this study was to identify the main content and cycle of the repair work, as well as examine and generalize the causes of deterioration in this building. In conclusion, there are 4 factors affecting the renovation of high-rise buildings, including air, light, water pressure and operation. There are several types of renovation works at skeleton and infill part arranged. In the public area, exterior wall repair and roof waterproofing could be seen in 15-years cycle. Balcony rail repair and furniture of revolving windows were repaired in 5~10-year cycle. In the private area, prefabricated bath, bath heater, bathtub at bathroom and sink at kitchens were replaced in 15-year cycle. In order to sustain good quality resident environment within existent high-rise housing buildings, it's necessary for construction industry to develop new technology and upgrade the function today. Government should also devote to the revision of the laws for housing environment improvement.

Abstract: Conflicts often occur with public facility construction. In sociology terms, the factor caused opposite opinions and flights from neighborhood people called NIMBY (Not In My Back Yard) phenomenon. Although NIMBY has been mentioned and discussed in lots of related researches, but there is no particular one to focus on making NIMBY phenomenon into quantization based on construction job-site interface. In this study, the Wastewater Sewer System construction project has been taken as a real case to find main factors caused NIMBY phenomenon and then makes the affiliated NIMBY phenomenon into quantization. The Wastewater Sewer System construction project is taken as the demonstration case due to wastewater facility belong to low accepting and high NIMBY within all public construction projects. In this study, the questionnaire and consulting survey are made to investigate the professional opinions of experts of sewer system facility and NIMBY response of citizens. The questionnaire is designed by fuzzy linguistic scale and quantized by Fuzzy Delphi Method. Then mainly factors caused NIMBY phenomenon and corresponding improvement measures are derived by the result of questionnaires and anti-NIMBY self-check list which can be established and used in daily process at construction job-site. This research develops NIMBY curves to estimate the NIMBY affection of citizens under the unsure circumstance of noise, air and water pollution with sewer system construction. Also the fuzzy rule base can be discovered by predicting NIMBY affection under the various violence of noise, air and water pollution in Fuzzy Inference Method. The anti-NIMBY self-check list for sewer system construction developed by this study can be used for examining the factor caused NIMBY and finding corresponding improvement measures in pre-construction period and construction period for managing workers at construction field. During construction period, the NIMBY Conflict Index system calculated from fuzzy rule based on NIMBY affection can be executed persistently to control NIMBY affection to avoid NIMBY conflict events happened.

Abstract: The design of reinforced concrete beams has usually focused on the ultimate flexural capacity and disregarded the lateral stability of the beams. However, the development of high-strength concrete and the implementation of new construction techniques increase the use of longer and deeper concrete beams, which makes the lateral instability a primary concern of failure in concrete bridges. In particular, the lateral stability should be more taken into consideration in the construction and erection phases due to inadequate lateral supports. Thus, an experimental study was carried out to evaluate the lateral torsional buckling of reinforced concrete beams with initial geometric imperfections. The lateral flexural and torsional rigidity expressions, which could account for the flexural, torsional, and shrinkage cracking of concrete, the contribution of longitudinal and shear reinforcement, and the nonlinearity of materials, were proposed for rectangular reinforced concrete beams. Finally, this study proposed an analytical formula to estimate the buckling loads of initially imperfect reinforced concrete beams. The estimates of the study showed close agreement with the experimental values.

Abstract: Dramatic failure of pile foundations caused by the soil liquefaction was founded leading to many studies for investigating the seismic behavior of pile. The failures were often accompanied with settlement, lateral displacement and tilting of superstructures. Therefore soil-structure interaction effects must be properly considered in the pile design. Two tests by using the centrifuge shaking table were conducted at an acceleration field of 80 g to investigate the seismic response of piles attached with different tip mass and embedded in liquefied or non-liquefied deposits during shaking. It was found that the maximum bending moment of pile occurs at the depth of 4 m and 5 m for dry sand and saturated sand models, respectively. The more tip mass leads to the more lateral displacement of pile head and the more residual bending moment.

Abstract: For the connection stiffness and strength prediction, Eurocode has showed an inadequacy as it will be affected by the thin-walled behaviour of cold-formed steel in actual structural performance. This paper performs a study on the connection stiffness prediction for cold-formed steel top-seat flange cleat connection with various angle thickness. Validated finite element modelling technique is applied for further advanced investigation. From the developed finite element models, it was realized that Eurocode has overestimated by the analytical stiffness prediction using component method for the studied connection which reduces the structural integrity in the design stage. A new proposal on connection stiffness prediction with influence of angle thickness for cold-formed steel top-seat flange cleat connection is presented to assist practicing engineers to design the cold-formed connection in light steel framing.

Abstract: In this paper, a pseudo-single-degree-of-freedom system identification procedure is developed to investigate the dynamic characteristics of energy-dissipated buildings equipped with symmetric ductile braces (SDBs). The primary structure is assumed to be linear on account of substantial reduction of seismic forces due to the installation of SDBs for which a bilinear hysteretic model is considered. The hysteretic model is in turn characterized by a backbone curve by which the multi-valued restoring force is transformed into a single-valued function. With the introduction of backbone curves, the system identification analysis of inelastic structures is significantly simplified. The proposed algorithm extracts individually the physical parameters of each primary structure and each energy-dissipation device that are considered useful information in the structural health monitoring. A numerical example is conducted to demonstrate the feasibility of using the proposed technique for physical parameter identification of partially inelastic energy-dissipated buildings.

Abstract: The present work develops a novel procedure of establishing a amplitude-dependent time series model for a nonlinear system and estimating the instantaneous modal parameters of the system from the dynamical responses. The undetermined coefficient in a amplitude-dependent autoregressive with exogenous input (amplitude-dependent ARX) model are assumed as function s of amplitude and are expanded by shape functions constructing by moving least-squares with polynomial basis functions. The amplitude of dynamical responses could be obtained by Hilbert transform. The instantaneous modal parameters of the system are directly estimated from the coefficient in the amplitude-dependent ARX model. Finally, the proposed approach is applied to process measured data for a frame specimen subjected to a series of base excitations in shaking table tests. The specimen was damaged during testing. The identified modal parameters are consistent with observed physical phenomena.

Abstract: Many probabilistic scheduling models have been developed to determine the duration of construction projects. However, these models are not appropriate to capture the effect of the factors that are involved construction interface problems on the durations of multiple activities. This work presents a simulation-based probabilistic scheduling model that includes the impact of construction interface problems on the duration of building projects. The proposed model is established according to an activity duration model and a work-group (WG)-based schedule network. The activity duration model is applied to reflect the effects of general factors on the duration of each activity; the WG-based schedule network is employed to evaluate the effects of construction interface problems on the durations of multiple activities. The results of applying the proposed model to an example project reveal that the duration of a project can be over-optimistically estimated if the effects of construction interface problems are neglected.