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Nonlinear response history analysis (NLRHA) procedure is one of the most precise and accurate numerical method to compute the seismic demands of high-rise structures but is complex, rigorous, and time-consuming and requires a lot of expertise for nonlinear modelling and results interpretation. Therefore, practicing engineers in developing countries like Pakistan still use the simplified analysis procedures to compute the seismic demands. Among the simplified analysis procedures, equivalent lateral force and response spectrum analysis procedures are widely used for the design purpose. However, other procedures have also been proposed in the recent past to accurately capture the higher mode effects in mid-to-high-rise structures. In the current study, results of a forty-story core wall building are used to check the relative accuracy and ease of application of different simplified analysis procedures. Furthermore, a modal decomposition technique is used to separate the modal responses from the NLRHA results, and a mode wise comparison of different demand parameters for different simplified procedures is performed. The current study has been used to clearly identify the reasons of inaccuracies in different simplified procedures. Furthermore, a simplified analysis procedure is proposed to accurately estimate the seismic demands of high-rise buildings and the possible solutions to improve their predictions. [ABSTRACT FROM AUTHOR]

The use of grout in conventional reinforced masonry construction increases the cost and time of construction but allows walls subject to out-of-plane loads an enhanced ability to span between lateral support levels. An experimental investigation including a total of 21 walls was conducted in an attempt to identify potential alternatives to conventionally grouted walls. The strength and serviceability of walls containing unbonded reinforcement anchored at its ends was evaluated. All walls were two and a half blocks wide and 14 courses tall and were constructed in running bond using standard 200 mm concrete blocks. Six replicate unreinforced and partially grouted, conventionally reinforced walls served as control specimens. Walls with unbonded reinforcement were determined to be inherently stable with maximum loads approaching those of partially grouted, conventionally reinforced walls. If used in practice, these walls would need to be limited to indoor exposures due to the wide crack widths that develop. [ABSTRACT FROM AUTHOR]

The research was initiated to investigate the performance of fiber-reinforced concrete for protecting people or assets in the building against the explosion or debris missiles. The fiber-reinforced concrete has the difficulty with being applied in the actual construction conditions with the normal ready-mixed concrete system. The fibers for the protection performance require high toughness to endure the huge energy from an explosion, but the large amount of the fiber is required. The required amount of fibers can result in decreased workability and insufficient dispersion of fibers. It has been difficult to apply fiber-reinforced concrete on field placing with the ready-mixed concrete system of plant mixing, delivering, and placing. This research carried out the investigation of properties of combined fiber of steel and polymeric fiber to improve workability and agitating in the mixer. Based on the preliminary experimental test results in a laboratory, combined fiber-reinforced concrete was applied on the actual field construction of chemical plant. According to the results from the laboratory tests and application in the real construction project, it is expected to introduce the combined fiber for desirable mechanical performance with less adverse effect on workability of the mixture. [ABSTRACT FROM AUTHOR]

Although automation has been actively and successfully used in different industries since the 1970s, its application to the construction industry is still rare or not fully exploited. In order to help provide the construction industry with an additional incentive to adopt more automation, an investigation was undertaken to assess the effects of digital fabrication (dfab) on productivity by analyzing the cost and time required for the construction of a robotically-fabricated complex concrete wall onsite. After defining the different tasks for the conventional and robotically fabricated concrete wall, data was collected from different sources and used in a simulation to describe the distribution of time and cost for the different construction scenarios. In the example, it was found that productivity is higher when the robotic construction method is used for complex walls, indicating that it is possible to obtain significant economic benefit from the use of additive dfab to construct complex structures. Further research is required to assess the social impacts of using dfab. [ABSTRACT FROM AUTHOR]

The response of reinforced concrete (RC) shear wall as a lateral resisting member has been studied extensively, but it still demands a general practical model that identifies the envelope within which load–drift paths occur during cyclic loading. Such a broad model is vital to ensure adequate lateral strength to resist reversal loadings imposed on these walls during earthquake events and ductility to measure inelastic deformation capabilities. A new model to define the backbone curve is developed in this paper for squat, intermediate, and slender flanged and non‐flanged RC walls. The most common failure modes observed in the field and laboratory experiments are investigated and incorporated in the proposed model to estimate the response of these walls from elastic range until ultimate failure. The main parameters controlling the estimation of drifts that features the backbone curve thresholds are presented in this paper. The results of proposed model are compared with the outcomes of 117 specimens experimentally tested by other researchers. Also, the results are compared with Federal Emergency Management Agency (FEMA) 356, the updated American Society of Civil Engineers (ASCE)/Structural Engineering Institute (SEI) 41, and Eurocode (EC8 and EC2) provisions which reveal that only one general model, proposed in this paper, can capture the response of RC structural walls with an aspect ratio ranging from 0.35 to 2.5 and an axial load ratio from 0 to 0.4 with good agreement with experimental outcomes. [ABSTRACT FROM AUTHOR]

As a result of the 2010-2011 Canterbury earthquakes, over 60% of the concrete buildings in the Christchurch Central Business District have been demolished. This experience has highlighted the need to provide guidance on the residual capacity and repairability of earthquake-damaged concrete buildings. As limited testing has been performed on repaired components, this study focuses on the performance of severely-damaged lightly-reinforced concrete walls repaired through replacement of reinforcement and concrete in the damaged region. The damage prior to repair included buckling and fracture of longitudinal reinforcement, crushing and spalling of concrete, and, for one of the two specimens, out-of-plane instability of the gross section. Prior to repairing the wall specimens, tensile testing of reinforcement with welded connections was conducted to verify acceptable performance of welds suitable for reinstating the damaged reinforcement. Repairs to the specimens consisted of removal of damaged concrete through either hydrodemolition or jack hammering, followed by cutting and removal of damaged reinforcement and reinstatement of new reinforcement and repair mortar. The two repaired wall specimens were tested using a standard protocol that was identical to that used for one of the two original wall specimens. Aside from a difference in the elastic stiffness, the load-deformation responses of the repaired specimens were similar to that of the originally-tested specimen through to the first loading cycle at 2.0% drift, beyond which strength degradation was more pronounced for the repaired specimens. The overall performance of the repaired walls relative to the original wall indicates that it is feasible to achieve acceptable performance of severelydamaged concrete walls repaired through replacement of reinforcement and concrete in the damaged region. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study conducted to investigate the seismic performance and out-ofplane response of three rectangular doubly reinforced ductile wall specimens subjected to an in-plane cyclic quasi-static loading. The specimens were half-scale, representing the first story of four story prototype walls designed according to NZS3101:2006. The experimental program including details of the specimens, material properties, test setup, loading protocol and instrumentation is described. Also, the test observations, with focus on the significant stages of wall response as well as the failure patterns of the specimens, are reported considering the correlation between seismic damage and lateral drift. Two of the specimens failed at 2% drift, and their failure modes comprised of bar fracture, bar buckling, concrete crushing and out-of-plane instability. The failure pattern of the third specimen was pure out-of-plane instability which proved to have the potential to cause sudden collapse of slender ductile walls that are designed to resist other failure modes. In light of the test results, the efficacy of wall design provisions in the New Zealand concrete design standard (NZS3101) associated with the observed failure modes is scrutinised. [ABSTRACT FROM AUTHOR]

In this paper a novel RC (Reinforced Concrete) shear wall named the slotted RC wall is presented. The main feature of the novel wall is the vertical slots along the wall, equipped with steel energy dissipation links. The slotted wall is designed to improve the deformation capacity and control the damage for the conventional shear wall. To deeply investigate the seismic performance of the proposed slotted wall, five wall specimens were designed, including a conventional shear wall and four slotted walls with different slot widths and shear link sizes. Quasi-static cyclic test was conducted. The test results presented much improved energy dissipation capacity in the slotted walls compared with the conventional wall. The slotted configuration decreases the stiffness and bearing capacity of the wall compared with the conventional RC shear walls, and slightly enhances the deformation capacity of the wall. This enhanced deformation capacity is most evident in the slotted wall with the weakest energy dissipation links, which did not sustain damage to the RC components under a drift ratio of 1/100, and failed under a drift ratio of 1/36. A numerical model of the slotted wall was constructed and the results are compared with the experimental results, showing good agreement and confirming the effectiveness of the slotted wall configuration. [ABSTRACT FROM AUTHOR]

Projectiles, such as turbine blades, can be released in an accident and impact structures. Airplanes and other flying objects can also become impact projectiles. These impacts occasionally cause fire when fire loads, such as oil, fuel, and other combustible materials, are present. This study examines the thermal insulation performance of concrete plates and the structural fire behavior of load-bearing reinforced concrete walls that are exposed to fire after a high-velocity impact by a hard projectile. Impact and fire tests were carried out using small-scale concrete plates and reinforced concrete walls. The results show the influence of local damage and the advantage of short-fiber reinforced concrete subjected to impact loads and fire. [ABSTRACT FROM AUTHOR]

Digital fabrication represents innovative, computer-controlled processes and technologies with the potential to expand the boundaries of conventional construction. Their use in construction is currently restricted to complex and iconic structures, but the growth potential is large. This paper aims to investigate the environmental opportunities of digital fabrication methods, particularly when applied to complex concrete geometries. A case study of a novel robotic additive process that is applied to a wall structure is evaluated with the Life Cycle Assessment (LCA) method. The results of the assessment demonstrate that digital fabrication provides environmental benefits when applied to complex structures. The results also confirm that additional complexity is achieved through digital fabrication without additional environmental costs. This study provides a quantitative argument to position digital fabrication at the beginning of a new era, which is often called the Digital Age in many other disciplines. [ABSTRACT FROM AUTHOR]

During cold weather precast wall construction, in-situ heating of the grout used in grouted dowel connections is usually conducted for short periods of time. Hence, early-age exposure to subfreezing conditions may affect the quality of the grout and subsequently the bond strength of the connection, which can compromise structural integrity. In this study, grout specimens typical of that used in precast wall construction were initially cured at ambient conditions for one day and then placed inside a walk-in environmental chamber at subfreezing temperatures. The hardened grout properties and bond strength of the connection were examined and compared to that of specimens cured at ambient temperature. The compressive strength of the grout was monitored at temperatures of 1°, −10° and −20 °C. The effect of subfreezing exposure on the mechanical properties, hydration process and pore size distribution of the grout were examined. It was found that early-age subfreezing curing temperatures reduced the compressive strength of the grout, leading to increased dowel embedment length to achieve bar fracture. The bond strength of the connection remained proportional to the square root of compressive strength, even subsequent to early-age exposure to subfreezing temperature. [ABSTRACT FROM AUTHOR]

The electromagnetic shielding characteristics according to the material composition of foamed concrete, which was manufactured to reduce environmental pollution and to economically apply it in actual building walls, were researched herein. Industrial by-products such as ladle furnace slag (LFS), gypsum, and blast furnace slag (BFS) were added to manufacture foamed concrete with enhanced functionalities such as lightweight, heat insulation, and sound insulation. The electrical characteristics such as permittivity and loss tangent according to the foam and BFS content were calculated and measured. Free space measurement was used to measure the electromagnetic shielding characteristics of the actually manufactured foamed concrete. It was confirmed that electromagnetic signals were better blocked when the foam content was low and the BFS content was high in the measured frequency bands (1–8 GHz) and that approximately 90% of the electromagnetic signals were blocked over 4 GHz. [ABSTRACT FROM AUTHOR]

“Check and monitoring of condition of concrete slurry wall, jet-grouting and frozen soil fences by crosshole sounding method in underground construction” includes investigation results on the state of massifs of artificial soils established using a set of geophysical acoustic methods. Object of investigation are slurry wall panels’ body and joints, jet-grouting and frozen soil underground fences. Methods of geophysical investigation are crosshole acoustic and ultrasonic sounding from holes or embedded tubes. For investigation use crosshole sounding apparatus APZ-1 developed by LLC “Geodiagnostika” and ultrasonic device Pulsar 2.2 DBS. The author postulates that non-destructive testing provides the most accurate information about the state of the enclosing structure in the place of manufacture in the underground space. [ABSTRACT FROM AUTHOR]

The superimposed reinforced concrete wall in which both the walls and slabs are semi-precast superimposed reinforced concrete components has been widely used to construct high-rise residential buildings in some seismic regions of China. This article aims to investigate the seismic performance and reveal the inherent damage mechanism of this wall. Quasi-static tests of two full-scale superimposed reinforced concrete walls with I-shaped cross sections, consisting of the walls in orthogonal directions and two T-shaped cast-in-place boundary elements, were conducted. Through the test, the behavior of the horizontal joints between the wall panels and the foundation; the behavior of the vertical connections between the wall panels of orthogonal direction; the reliability of the connections between precast and cast-in-place concrete; and the lateral load, deformation, and energy dissipation capacities of the specimens are evaluated. In addition, a refined numerical model based on the multi-spring model was adopted to assess the seismic performance of the superimposed reinforced concrete walls with I-shaped cross sections. The reliability of this model was validated through comparison with the experimental data. This study offers valuable experimental data and numerical model references for future seismic performance assessments of superimposed reinforced concrete wall structures. [ABSTRACT FROM AUTHOR]

This paper investigates the multi-species and multi-fields transport processes in the concrete wall of sea immersed tube tunnel, exposed externally to sea water and internally to road traffic. A thermo–hydro-ionic (THI) model is established for the transport processes, taking into account the heat, mass and electrical charge conservations, the electrical neutrality and solid-solution equilibria in the representative elementary volume (REV) of material. Then, the characteristic lengths for drying and wetting are proposed for the tunnel wall through simplified model of moisture transport to define different durability patterns for tunnel wall, and the associated durability risks are identified. The THI model is applied to the immersed tube tunnel of Hong Kong–Zhuhai–Macau (HZM) sea link project, and the transport processes are simulated for a service life of 120 years and different working cases. The analysis shows that: (1) the thermal gradient has more important impact on transport processes than the external sea water pressure on tunnel wall; (2) the drying and wetting extents are overlapped through the wall thickness at 120 years, and the internal drying and external leaching condition the multi-species transport; and (3) the corrosion initiation range attains 65 cm at 120 years but the corrosion current is below the depassivation value (0.1 μ A/cm 2 ). [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the effect of thickness and moisture on temperature distributions of reinforced concrete walls under fire conditions. Toward this goal, the first three wall specimens having different thicknesses are heated for 2 h according to ISO standard heating curve and the temperature distribution through the wall thickness is measured. Since the thermal behavior of the tested walls is influenced by thickness, as well as moisture content, three additional walls are prepared and preheated to reduce moisture content and then tested under fire exposure. The experimental results clearly show the temperatures measured close to the fire exposed surface of the thickest wall with 250 mm thickness is the highest in the temperatures measured at the same location of the thinner wall with 150 mm thickness because of the moisture clog that is formed inside the wall with 250 mm of thickness. This prevents heat being transferred to the opposite side of the heated surface. This is also confirmed by the thermal behavior of the preheated walls, showing that the temperature is well distributed in the preheated walls as compared to that in non-preheated walls. Finite element models including moisture clog zone are generated to simulate fire tests with consideration of moisture clog effect. The temperature distributions of the models predicted from the transient heat analyses are compared with experimental results and show good agreements. In addition, parametric studies are performed with various moisture contents in order to investigate effect of moisture contents on the thermal behaviors of the concrete walls. [ABSTRACT FROM AUTHOR]

Precast post-tensioned concrete rocking wall system is an innovative damage avoidance structural system for seismic regions. Past experimental works on the dynamic performance of rocking walls have identified the presence of high-frequency acceleration spikes in both lateral and vertical directions during the impact of wall base with the foundation. These acceleration spikes, acting together, can cause shear slip at the wall-foundation connection. This study is focused on the development of a computer model that can predict these acceleration spikes along with the identification of their effects on the dynamic performance of rocking walls. For this purpose, impact phenomenon at the wall-foundation joint has been discussed in detail and some general guidelines are set for the two important parameters of impact or contact modeling named as contact stiffness and contact damping. The finite element numerical models, based on the proposed guidelines, are found to predict the overall dynamic behavior of rocking walls along with the acceleration spikes quite efficiently. The acceleration spikes are found to be dependent on the lateral velocity at impact and the initial contact stiffness. So a velocity-dependent energy dissipation device along with a soft contact is found to be suitable for reducing these effects. [ABSTRACT FROM AUTHOR]

The thermal performance of an opaque water wall system is numerically investigated using the shear-stress transport (SST) k – ω turbulence model and the Discrete Ordinates radiation model for typical winter and summer climate conditions in Sydney, Australia. With a periodic sol-air temperature specified on the outside Perspex panel, the energy performance of the water wall system is examined over a range of water wall thicknesses. The computational fluid dynamics (CFD) model is compared with an experimentally validated transient heat balance model (THBM), and a fair agreement between the CFD model and the THBM results is achieved. The present numerical results indicate that the performance of the opaque water wall system is improved by increasing the thickness of the water column under the winter climate condition in Sydney. It is also found that less supplementary energy is required in winter than that in summer in order to maintain a comfortable interior temperature. Further, a comparison between the present water wall system and a conventional concrete wall system shows that the water wall system performs significantly better than the concrete wall system of the same thickness in the winter climate of Sydney, whereas both the water wall and concrete wall systems have a similar performance in terms of energy savings in the summer climate of Sydney. [ABSTRACT FROM AUTHOR]

Recent studies of plane parallel flows have emphasised the importance of finite-amplitude self-sustaining processes for the existence of alternative non-trivial solutions. The idea behind these mechanisms is that the motion is composed of distinct structures that interact to self-sustain. These solutions are not unique and their totality form a skeleton about which the actual realised motion is attracted. Related features can be found in spherical Couette flow between two rotating spheres in the limit of narrow-gap width. At lowest order the onset of instability is manifested by Taylor vortices localised in the vicinity of the equator. By approximating the spheres by their tangent cylinders at the equator, a critical Taylor number based on the ensuing cylindrical Couette flow problem wouldappearto provide a lowest order approximation to the true critical Taylor number. At next order, the latitudinal modulation of their amplitudeasatisfies the complex Ginzburg-Landau equation (CGLe) whereis latitude scaled on the modulation length scale,tis time andis proportional to the excess Taylor number. The amplitudeagoverned by our CGLe is linearly stable for allbut possesses non-decaying nonlinear solutions at finite, directly analogous to plane Couette flow. Furthermore, whereas the important balancesuggests that the Taylor vortices ought to propagate as waves towards the equator with frequency proportional to latitude, the realised solutions are found to exist as pulses, each locked to a discrete frequency, of spatially modulated Taylor vortices. Collectively they form a pulse train. Thus the expected continuous spatial variation of the frequency is broken into steps (forming a staircase) on which motion is dominated by the local pulse. A wealth of solutions of our CGLe have been found and some may be stable. Nevertheless, when higher-order terms are reinstated, solutions are modulated on a yet longer length scale and must evolve. So, whereas there is an underlying pulse structure in the small but finite gap limit, motion is likely to be always weakly chaotic. Our CGLe and its solution provides a paradigm for many geophysical and astrophysical flows capturing in minimalistic form interaction of phase mixing, diffusionand nonlinearity. [ABSTRACT FROM AUTHOR]

A seismic collapse evaluation study of buildings with rigid walls and flexible roof diaphragms (RWFD) presented in the companion paper indicates that this type of structure, as designed to current seismic design provisions in the United States, does not satisfy FEMA P695 performance criteria for Risk Category II Buildings. The seismic performance of RWFD buildings is often characterized by large deformations and yielding in the roof diaphragm rather than in the vertical elements of the seismic force-resisting system (SFRS). In this paper, a new seismic design approach is proposed to account for flexible roof diaphragm response. The proposed approach relies on distributed yielding in the roof diaphragm as the predominant inelastic response under extreme ground shaking. This is obtained by strengthening the end diaphragm regions, thereby allowing yielding to spread deeper into the diaphragm. The basic steps of the design approach and its limitations are described. Avalidation study of the proposed design procedure is conducted for 17 RWFD building archetypes with wood roof diaphragms in accordance with the FEMA P695 methodology. The results of this study indicate that the proposed seismic design approach, produces a system that meets the probability of collapse requirement for a Risk Category II building of the FEMA P695 methodology under maximum considered earthquake ground motion for RWFD buildings with wood roof diaphragms. [ABSTRACT FROM AUTHOR]

Buildings having rigid walls and flexible roof diaphragms (RWFD) are a type of building construction widely used for light industry in the United States; they incorporate rigid in-plane concrete or masonry walls and flexible in-plane wood, steel, or hybrid roof diaphragms. In this first of two companion papers, the probability of collapse of this type of building designed to current code provisions in the United States, given an MCE earthquake event, is evaluated according to the FEMA P695 methodology for a large set of representative building archetypes. The results of the study indicate that current code provisions for this type of building do not satisfy the collapse objective requirements of FEMA P695 under maximum considered earthquake ground motions. This is because the analysis provisions are based on assumed yielding of the walls rather than the roof diaphragm. Also, current code provisions considerably underestimate the period of RWFD buildings. To assist with creating provisions that take into account large flexible diaphragm deformations, a semi-empirical formula to estimate the fundamental period of RWFD buildings that accounts for roof diaphragm flexibility is derived in this paper. A new proposed seismic design approach for RWFD buildings is developed and evaluated in the second companion paper. [ABSTRACT FROM AUTHOR]

Development of sustainable concrete has now become a mandatory requirement today due to environmental problems posed by the production of conventional concrete. Many researchers focused their research toward finding alternate materials for cement, sand, steel, etc., and came out with good results. This paper focuses on feasibility of developing sustainable concrete using bamboo as infill, stiffener, and combination of infill and reinforcement in the wall panels. In addition, low-density polyethylene waste also tried as infill material with bamboo as diagonal member. The structural property of bamboo was studied for replacing the conventional steel by designing the wall panels with lower stiffness and weight to avoid the catastrophic effect. The strength and behavior of infill wall panels for different infill cases were studied under uniaxial in-plane loading. Parameters such as maximum load carrying capacity, load-deflection characteristics, and cost effectiveness of bamboo-based wall panel system were considered in the present study. From the experimental results, it was understood that bamboo-based wall panel behaved as a ductile member and failed after due to the formation of micro-cracks. Wall panel specimens were failed with an out-plan buckling and resisted the force such that the sudden collapse was avoided. It was concluded that an infill wall reduced lateral and vertical deflection, thereby decreasing the probability of collapse. Hence, an infill wall panel could be used as a substitute for conventional wall panel. [ABSTRACT FROM AUTHOR]

This study investigated amplitude-modulation effects on the heavy-weight floor impact sound caused by a vibration of concrete wall construction. The fundamental resonance of a floor in concrete wall construction consists of two closely spaced vibration modes. These modes were identified from experimental modal analysis of an actual multi-story building. The modes corresponded to in-phase and out-of-phase vibrations of the upper and lower floors. The rigidity of the side walls had influence on the difference between the natural frequencies of the two modes. Low-frequency modulated sounds were generated in a room by the simultaneous excitations of the two vibration modes. The heavy-weight impact sounds were analyzed using auditory experiments to determine the amplitude-modulation effects on the perceived annoyance. The highly modulated impact sounds were judged to be 3–5 dB more annoying than the one having the same level without modulation. Consequently, impact sound transmission from floors connected by less rigid side walls exhibited lower annoyance. [ABSTRACT FROM AUTHOR]

A compound deep cement mixing retaining wall system is a combination of deep cement mixing (DCM) columns and precast reinforced concrete walls. This type of retaining wall was used in a deep excavation for a reservoir construction project in a soft clay area in Thailand. During construction, an inclinometer casing was installed to monitor the lateral movement profiles of this retaining wall system until construction had been completed. Studies on the parameters that affect the lateral movements of retaining walls of this type are limited because of the complex geometry involved. In this paper, a three-dimensional numerical model is first calibrated using an instrumented case history. Then, an analysis of the results for this case history is presented to characterize the wall behavior in terms of the ground settlement induced by wall deflection during excavation and in terms of lateral wall movement. Finally, a parametric study is performed. The results provide information on the influence exerted on the lateral wall movement by the following factors: the elastic modulus of the DCM columns, the embedded length of the DCM columns, the size of the DCM columns, the thickness of the precast wall, the thickness of the soft clay layer and the berm size. The influences of these factors are compared and rated in terms of their degree of importance. [ABSTRACT FROM AUTHOR]

Different in situ and laboratory tests are commonly used to determine the nature of salts and to improve the comprehension of degradation mechanisms. Although laboratory tests are more accurate, in situ tests yield faster results and require a significantly lower budget. This study aimed at collecting data on nine case studies of buildings (26 sample's analysis) showing salt induced damage and assessing the potential of diagnosis techniques. Two in situ (test strips and a spectrophotometer-field kit) and three laboratory techniques [X-ray diffraction (XRD), X-ray fluorescence (XRF) and infrared spectroscopy (FTIR)] were carried out. The results showed the importance of collecting samples from different materials and locations. It is concluded that the combination of a thorough description of the areas affected by salt damage, a survey of the building's history, the consideration of its surrounding environmental conditions, and simple in situ tests is a useful and straightforward diagnostic tool. Although results of in situ tests agreed with the global results from the set of laboratory analyses, no single analytical method was considered sufficient to accurately identify all the damaging salts in a sample because each one showed intrinsic limitations. [ABSTRACT FROM AUTHOR]

RC walls (reinforced concrete) may be subdivided into three categories from the point of view of mechanical behavior which are mainly dependent on the geometric relationship of the height to the width (h/l). Also, the RC walls are defined as slender when this relationship is higher than 1.5, and considered short if it is less than 1.0. When the relationship is in between these two values, the element is called current or moderately slender RC wall. The use of RC walls in seismic regions is becoming more frequent. The reason is that RC walls, in addition to their enabling role in line to-screws of vertical loads, are particularly effective concerning resistance to horizontal forces, thus withstanding the greater part of the seismic action. The RC walls are shaping the behavior of structures, and play a critical role for security on several typologies of structures. This paper focuses on the analysis of the behavior of slender RC walls according to two different methods of reinforcement; the method of bands, and the classical method. A local approach is used by modeling the RC walls solicited under horizontal loading. The numerical model used for concrete is the model “Concrete Damage Plasticity” (CDP) and for steels, the elastic-plastic model serves to work the hardening isotropic. The models allow the visualization of the damage and determination of the failure mode. The numerical aspects are particularly detailed. [ABSTRACT FROM AUTHOR]

An experimental investigation was conducted to evaluate bar size factors used for the calculation of required lap splice lengths according to US and Canadian codes for concrete block masonry walls subjected to out-of-plane loads. Wall splice specimens were constructed in running bond with all cells fully grouted, and were tested under monotonically increasing four-point loading. Specimens were longitudinally reinforced with either No. 15, 20, or 25 reinforcing bars with varying lap splice lengths that were sufficiently short to ensure that a bond failure would precede a failure in flexure. Modifications to the bar size factors included in both codes were derived from the resulting test data. The evaluation of the test data shows that decreases to lap splice lengths could be considered for walls subjected to out-of-plane loads, which would facilitate construction. [ABSTRACT FROM AUTHOR]

The subject of this paper is a phase numerical analysis of early-age cracking of a reinforced concrete (RC) cylindrical tank wall, with a nominal unit capacity of 8,300 m³, under construction. Numerical calculations are based on the model that can analyze the behavior of such structures, including the temperature development originating from heat hydration, external conditions, the development of shrinkage, and mechanical properties in time. Aviscous-elastic concrete model with cracking was used. The real state of cracked wall segments 8 and 9 (Part I) is compared with the results of the numerical calculations. Moreover, the cracks' localization and sequence of cracking as a result of the numerical analysis is discussed. Based on the achieved numerical results, the design solutions of vertical construction joints in which the degree of reinforcement is increased to ensure their water-tightness (despite the use of a sealing tape) negatively affect the cracking state of the jointed walls. This is reflected in the extended cracking that leads to the occurrence of leakage. [ABSTRACT FROM AUTHOR]

Relying on a simplified one dimensional beam-like schematization of the problem, a yield design-based approach is developed for analyzing the potential failure of high rise walls (that are larger than the dimensions of experimental test furnaces) under fire conditions. The implementation of the method combines two original features: first, the preliminary determination of interaction diagrams reflecting the local decrease in strength of the wall due to thermal loading; second, the thermal-induced geometry changes which are explicitly accounted for in the overall failure design of the wall. Application of the approach is illustrated in either evaluating the fire resistance of a wall of given height or predicting the maximum height that the wall could reach for a prescribed fire exposure time. First results of this analysis point to the conclusion that wall failure due to fire loading is highly sensitive to its height. [ABSTRACT FROM AUTHOR]

This article presents recent research on the seismic resistance of coupled post-tensioned timber walls for use in multi-story buildings. The walls are constructed from laminated veneer lumber (LVL), post-tensioned with unbonded vertical tendons, and coupled together with mild steel U-shaped flexural plates (UFPs) as energy dissipating elements. The timber wall design follows the same principles as used for post-tensioned precast concrete wall systems, using U-shaped plates to obtain a “hybrid” system, where energy is dissipated through yielding of the plates, while the vertical post-tensioning provides the restoring force. In this project, the same principles are applied to timber coupled walls. A series of quasi-static cyclic and pseudo-dynamic tests have been carried out to verify the applicability of the concept and the feasibility of the construction technology in timber buildings. The U-shaped plates showed stable energy dissipation characteristics and, in combination with the post-tensioning, desirable re-centering hysteretic behavior typically referred to as “flag-shape”. Because of the simplicity of these elements and the low cost of implementation, they have good prospects for practical application. [ABSTRACT FROM AUTHOR]

It can take many years to complete the construction of deep, wide and long excavations in urban environments. In seismically active areas, there is a finite probability that a significant earthquake could take place during the construction period. The designer and builder are confronted with the need not only to maintain control of ground and retaining wall movements during the normal construction conditions but also to protect surrounding buildings during a seismic event. It follows that the seismic loads from adjacent structures and their foundations must be considered together with the available load pathways through the propping system. The paper considers the available methods of design and proposes a performance-based design philosophy in which the temporary shoring system and permanent installation are designed for static loading conditions and for the seismic condition only in as much as the performance objectives of adjacent buildings are achieved for various levels of earthquake shaking. An example of the use of performance-based design is presented for the effects of a 130 m tall building of 30 m square plan upon the temporary shoring system for a long and wide excavation. The results obtained are compared with code-based calculations and general conclusions are drawn. [ABSTRACT FROM AUTHOR]

Aim The aim of this study was to compare the acoustic satisfaction in residential multi-storey buildings with different wall constructions with a similar weighted sound reduction index R ′ w : Heavy construction (monolithic concrete walls) and Light construction (staggered double walls). Light constructions are known to have a lower sound insulation especially at low frequencies. Our research question was does this difference affect the overall acoustic satisfaction among occupants. Materials and methods Four and two residential multi-storey buildings were chosen to represent building types Heavy and Light, respectively. A questionnaire was distributed to each dwelling. Seventy-two and eighty-seven respondents were obtained, respectively, with response rates of 62% and 54%. Some sound insulation measurements were carried out for verification purposes. Results As expected, the airborne sound insulation was worse below 160 Hz in building type Light, while the R ′ w values were nearly equal, 56–57 dB. The satisfaction with sound insulation did not differ between the two building types. All neighbour noise sources were rated equally disturbing in both building types. The building types did differ from each other with respect to the effects of noise on sleep. Conclusions The results suggest that when the airborne sound insulation is close to 55 dB R ′ w , the construction type does not necessarily affect the acoustic satisfaction. The results also suggest that R ′ w explains better the subjective rating of sound insulation than R ′ w + C 50–3150 . [ABSTRACT FROM AUTHOR]

Structural walls (also known as shear walls) are one of the common lateral load resisting elements in reinforced concrete (RC) buildings in seismic regions. The performance of RC structural walls in recent earthquakes has exposed some problems with the existing design of RC structural walls. The main issues lie around the buckling of bars, out-of plane defonnation of the wall (especially the zone deteriorated in compression), reinforcement getting snapped beneath a solitary thin crack etc. This study compares performance of a typical wall designed by different standards. For this purpose, a case study RC shear wall is taken from the Hotel Grand Chancellor in Christchurch which was designed according to the 1982 version of the New Zealand concrete structures standard (NZS3101:1982). The wall is redesigned in this study to comply with the detailing requirements of three standards; ACI-318-11, NZS3101:2006 and Eurocode 8 in such a way that they provide the same flexural and shear capacity. Based on section analysis and pushover analysis, nonlinear responses of the walls are compared in terms of their lateral load capacity and curvature as well as displacement ductilities, and the effect of the code limitations on nonlinear responses of the different walls are evaluated. A parametric study is also carried out to further investigate the effect of confinement length and axial load ratio on the lateral response of shear walls. [ABSTRACT FROM AUTHOR]

Highlights: [•] Coupled walls provide superior lateral stiffness when remain elastic. [•] Coupled walls behave as stiff coupled system for wind and moderate seismic loads. [•] Coupling beams degrade prior to the plastic capacity of the system being achieved. [•] Coupled walls evolve into a collection of linked wall piers at high seismic loads. [•] Reducing coupling beam capacity could be a key in developing constructible design. [Copyright &y& Elsevier]

An experimental program has been carried out to study the performance of partially grouted, nominally reinforced (PG-NR) concrete block structural walls under in-plane seismic loading on a shake table. Five reduced-scale structural walls were constructed and tested under scaled versions of the 1940 El Centro, California earthquake, using its N-S component record with a constant axial compression load that represented a single-story building. The test walls were grouped into three categories. Type I and III walls had reinforcement at the wall end cells only, with vertical reinforcement ratios of 0.07 and 0.12%, respectively, based on the gross cross-sectional area of the walls. Type II walls were similar to Type I walls, but with an additional reinforcement bar located midlength of the wall with a vertical reinforcement ratio of 0.10%, also based on the gross cross-sectional area of the wall. The experimental results were documented and discussed with respect to wall lateral load capacity, stiffness degradation, period shift, displacement ductility levels attained, and relevant seismic-force reduction factors. The test results showed that PG-NR masonry walls can comprise a ductile seismic force-resisting system. Subsequently, PG-NR masonry walls have the potential to bridge the gap between unreinforced and reinforced masonry systems. The use of PG-NR masonry also results in a reduced cost compared with traditional reinforced masonry systems used in seismic zones that are typically fully grouted within the plastic hinge zones and require higher reinforcement ratios. [ABSTRACT FROM AUTHOR]

This paper describes the full-scale experimental evaluation of the out-of-plane flexural response of fully grouted RC masonry walls subjected to uniform static pressure and to dynamic pressure resulting from an explosion. The investigation was performed as part of a larger effort to improve the design methodologies for reinforced masonry subjected to blast loading. The masonry walls were non-load-bearing and vertically spanning, which represents a significant amount of common construction in the United States. Both single-wythe and veneer wall sections were evaluated. Two types of concrete masonry units were used, i.e., conventional and A-block concrete masonry units. The results of the program provide a better understanding of the ultimate dynamic capacities and ductility of reinforced masonry walls-both single-wythe and veneer walls-which will ultimately help engineers produce designs that are safer and more economical. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of positions of macro encapsulated PCM in concrete walls was investigated. [•] PCM laminated within concrete walls reduced the maximum temperature by up to 4°C. [•] PCM placed on inner side of concrete walls reduced relative humidity (RH) by 16%. [•] By reducing RH, PCM models provide comfortable and healthy indoor environment. [•] Application of PCM is economically visible with a recovery period of 11 years. [ABSTRACT FROM AUTHOR]

The use of tensile strain-hardening, high-performance fiber-reinforced concrete (HPFRC) in low-rise structural walls as a means to simplify reinforcement detailing was evaluated. To validate the proposed simplified reinforcement design, five HPFRC cantilever low-rise wall specimens with shear span-to-length ratios of either 1.2 or 1.5 were tested under large displacement reversals. For comparison purposes, four reinforced concrete (RC) walls detailed according to the seismic provisions of ACI 318-05 were also tested. The HPFRC walls had little or no confinement reinforcement in the boundary regions and reduced web distributed reinforcement compared with that in the RC walls. The RC walls exhibited drift capacities of up to 2.3%, whereas the HPFRC walls sustained drifts of up to 3%. As expected, an increase in shear stress demand led to a decrease in drift capacity for both RC and HPFRC walls. No indication of early concrete crushing or buckling of the longitudinal reinforcement was observed in the boundary regions of the HPFRC walls, even when no confinement reinforcement was provided. [ABSTRACT FROM AUTHOR]

Numerous thin concrete walls failed in compression during the 2010 Chile earthquake. Experiments on small wall elements indicate that thin concrete walls without tied vertical reinforcement may fail very suddenly at uniform compression strains as low as 0.001 due to the thin layer of concrete between two layers of reinforcement becoming unstable. A test on a wall subjected to axial compression and strong-axis bending demonstrated that unlike a tied column, a thin concrete wall can suddenly lose all axial load-carrying capacity. Nonlinear response history analysis of a typical Chilean high-rise shear wall building indicates small global drift demands and correspondingly small curvature and compression strain demands when subjected to the ground motions measured in Santiago, which explains why most buildings were not damaged. Nonlinear finite element analysis of a typical wall step-back irregularity indicates the increase in maximum compression strains due to a reduction in wall length is much larger than predicted by a sectional analysis. Based on all the results of the current study, a number of significant changes are proposed for the 2014 edition of CSA A23.3 to avoid compression failures of thin concrete walls, including limiting the axial compression force applied to thin bearing walls, accounting for unexpected strong-axis bending of thin bearing walls, and limiting the compression strain demands on thin concrete shear walls. [ABSTRACT FROM AUTHOR]

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In May 2011, African Barrick Gold, owner of the North Mara Gold Mine in northern Tanzania, announced a plan to erect a three-metre-high concrete wall to enhance security against incursions from local (displaced) populations. Taking this wall as both metaphorical and material, this paper questions the psychological impact of displacement on "displacers." How does this subject avoid psychic implosion? My review identifies legal infrastructure, mythologies of Canadian benevolence, CSR discourses, and community consultations as operating to provide psychic scaffolding for this dominant subject, who is thus inured against psychic distress and implosion in response to conditions of what can be deemed routine structural violence. [ABSTRACT FROM AUTHOR]

The Whiteman Creek Bridge replacement project represents a synthesis of accelerated bridge construction, ultra-high-performance concrete, and fiber-reinforced polymer reinforcement to deliver accelerated construction and durability at reasonable cost. The project involved the replacement of an existing three-span concrete bridge with a single 40 m (130 ft) span bridge during a seven-week highway closure. This bridge uses 90% prefabricated components, including precast concrete abutments, wing walls, deck elements, and steel girders. The superior qualities and high strength of ultra-highperformance concrete were also used to help drive the evolution of accelerated bridge construction by reducing the dimensions of joints between precast concrete elements and by eliminating formwork on the deck. For enhanced durability, glass-fiber-reinforced polymer (GFRP) bars were used in the top reinforcing mat of the precast concrete deck elements, while the bottom reinforcing mat used conventional black reinforcement steel. The new cast-in-place concrete barrier walls also used GFRP bars. [ABSTRACT FROM AUTHOR]

Hemp concrete is a sustainable lightweight concrete that became popular in the field of building construction because of its thermal and environmental properties. However; available experimental data on its hygrothermal behavior are rather scarce in the literature. This paper describes the design of a large-scale experiment developed to investigate the hygrothermal behavior of hemp concrete cast around a timber frame through a spraying process; and then coated with lime-based plaster. The equipment is composed of two climatic chambers surrounding the tested wall. The experiment consists of maintaining the indoor climate at constant values and applying incremental steps of temperature; relative humidity or vapor pressure in the outdoor chamber. Temperature and relative humidity of the room air and on various depths inside the wall are continuously registered during the experiments and evaporation phenomena are observed. The influence of the plaster on the hygrothermal behavior of hemp concrete is investigated. Moreover; a comparison of experimental temperatures with numerical results obtained from a purely conductive thermal model is proposed. Comparing the model with the measured data gave satisfactory agreement. [ABSTRACT FROM AUTHOR]

SUMMARY This paper discusses modelling, analysis and design issues for a 55-storey hotel building recently planned for New York City, USA. The lateral force resistance of the investigated building primarily makes use of exterior reinforced concrete shear walls in one direction and exterior reinforced concrete moment frames in the other direction, in which tube action credited to the connection of the walls and frames was designed to play a significant role in the lateral stiffness and strength. In addition, a full-storey belt wall system, enclosing the entire perimeter of the building at approximately the mid-height, is expected to provide a considerable contribution to the lateral force resistance. In this paper, the contribution of tube action and the belt wall system to structural behaviour is investigated in terms of quantitative measures such as lateral drift, building dynamic properties and flange frame contribution to overturning moment resistance. In addition, axial force distribution among the various vertical members under lateral forces is discussed for each of the two principal building directions. Finally, the seismic behaviour of the investigated building is qualitatively discussed in order to propose a seismic force-resisting system classification into which this concrete tube system would fit. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: This research focuses on reinforced lightweight aggregate concrete walls. After performing a standard temperature rising fire-resistance test, the fire resistance performance and mechanic behavior of the wall sample are studied under a lateral horizontal load. Reinforced lightweight aggregate concrete walls and reinforced normalweight concrete walls are given the fire-resistance test under the same conditions, then their fire resistance performance and mechanical behaviors are compared. Taking into consideration the steel spacing, aggregate type, wall size, and high temperature as the wall sample variables. The research results showed that the reinforced lightweight aggregate concrete wall is superior to the reinforced normalweight concrete wall on ultimate load, yield load, cracked load, stiffness, ductility, and inter-story drift after a high-temperature fire-resistance test. In terms of failure patterns, for a reinforced lightweight aggregate concrete wall after a high-temperature fire-resistance test, the smaller the steel spacing the higher the yield load and ultimate load, but the worse the ductility. This result matched the results of the reinforced lightweight aggregate concrete wall without the high-temperature fire-resistance test and revealed that the reinforced lightweight aggregate concrete wall retained its mechanics after the fire-resistance test. [Copyright &y& Elsevier]

The accurate prediction of tendon stresses is a critical step in calculating the nominal flexural strength of unbonded post-tensioned concrete walls. The lateral load behavior of these walls is largely characterized by a single crack developing at the wall base with the unbonded tendons providing the tension needed for flexural moment resistance. Unlike members with bonded reinforcement, stresses in unbonded tendons cannot be found from strain compatibility and instead must be related to the wall lateral deformation. Previously developed equations for predicting tendon stresses in unbonded post-tensioned flexural members, including those in ACI 318-08, have focused on concrete beams and are inappropriate for concrete walls. A finite element model validated with experimental data from the testing of concrete walls was used to demonstrate the inaccuracy of current design provisions and other available equations for predicting tendon stresses. To provide a more accurate prediction of the unbonded tendon stresses in post-tensioned concrete walls that are designed for use in regions with low seismicity, an equation is proposed that is suitable for inclusion in future versions of ACI 318. [ABSTRACT FROM AUTHOR]

A number of different displacement-based design (DBD) methods have been put forward over the past decade in order to address shortcomings with current force-based design approaches. Considerable progress has been made in developing DBD procedures for a wide variety of structural typologies. However, the new displacement based design approaches are considerably more time-consuming for simple low- and medium-rise structures than quick force-based design methods such as the equivalent lateral force method. In this work, a new simplified displacement-based design approach, referred to as the energy-factor method, is described and applied to a number of case-study wall structures. The results of the method are compared with those obtained from the equivalent force-based design approach and the Direct DBD method. The performance of the method is then gauged through a series of nonlinear time-history analyses using spectrum-compatible accelerograms. The results indicate that the simple energy-factor method could offer excellent possibilities for the performance-based design of regular low- and medium-rise structures. [ABSTRACT FROM AUTHOR]

Thick concrete plates are currently used for offshore and nuclear containment concrete walls. In this research, five thick concrete slabs with a total thickness of 300 to 400 mm (12 to 16 in.) were tested under concentric punching loading. Four specimens had no shear reinforcement, whereas the remaining one included T-headed shear reinforcement consisting of vertical bars mechanically anchored at the top and bottom by welded anchor plates. The main focus of this research was to investigate the influence of the size effect on the punching shear strength of thick high-strength concrete plates. All tests without shear reinforcement exhibited brittle shear failures. The addition of T-headed shear reinforcement with a shear reinforcement ratio of approximately 0.68% by volume changed the failure mode to ductile flexural failure. The test results revealed that increasing the total thickness from 350 to 400 mm (14 to 16 in.) resulted in increased punching capacity and at the same time resulted in a small increase in ductility characteristics. An equation based on fracture mechanics principles is recommended to account for the size effect factor. The proposed equation is verified using the test results and is compared with the predictions of different design codes. [ABSTRACT FROM AUTHOR]