Massive Concrete Wall Research Articles

Japan’s Extreme Infrastructure: Fortress-ification, Resilience, and Extreme Nature

Abstract How have massive concrete walls become thinkable as resilient infrastructure for an extreme nature, and what will collective life become in the shadow of such concrete resilience? These questions hold increasing importance as cities and nations throughout the world contemplate the construction of giant concrete barriers to resist the forces of extreme weather and rising sea levels. This article turns to Japan’s ‘fortress-ification’ of its northeast coast with giant concrete seawalls in wake of the 2011 Great East Japan Earthquake in order to explore the convergence of resilience thinking, concrete walls, and extreme nature. Treating fortress-ification as an empirical phenomenon and analytic, the argument tracks the emergence of fortress-ification as a manifestation of a kind of resilience thinking that derives from a synthesis of logics of disaster prevention and disaster reduction. Ultimately, the argument posits that the resilience thinking behind fortress-ification engenders adaptation to extreme nature without providing meaningful environmental mitigation. The result is disaster infrastructure with highly questionable efficacy that seals the population within an ecologically empty present while restricting access to better alternative ecological futures.

Stress Development and Crack Monitoring of Massive Concrete Walls with Embedded Air-cooling Pipes

Stress Development and Crack Monitoring of Massive Concrete Walls with Embedded Air-cooling Pipes

Drying and shrinkage of massive concrete wall segments—3 years experiment and analytical observations

This paper presents 3 years lasting large scale experiment focusing on simultaneous measurements of drying profiles and shrinkage on massive concrete wall segments considering size effect. Three large specimens with thickness 20, 40 and 80 were accompanied by group of small specimens in order to measure additional parameters. Specimens were made from the same concrete mixture and placed in the same environment in the laboratory. Typical concrete mixture was used having water cement ratio 0.5 and average 28-days compressive strength 55 MPa. Pore relative humidity was measured in different depths using embedded plastic tubes and moisture meter, shrinkage (or swelling) strain was measured by embedded vibrating wire strain gauges. Special attention is paid and comments are stated to initial swelling up to 80 μm/m and to observed size effects in drying and shrinkage. Extensive data collected during this experiment were compared with results of various numerical models for shrinkage of concrete and with results of models for moisture transport in concrete. Discussion on the predictive capability of these models is provided. Calculation of apparent shrinkage from measured drying profiles of the wall segments using shrinkage point model is carried out and compared with measured shrinkage as well.

Influence of Structural Irregularities of Tserkov Building on its Dynamic Behavior under Induced Seismic Shock of Mining Origin

In the paper the influence of structural irregularities of a building on its dynamic behavior under a mining tremor was examined. A building of tserkov was taken into consideration as an example of irregular building. The geometry and the material properties of the tserkov resulted in irregularities of the stiffness of structure: the massive concrete walls were much more stiffer than the floor slab and the structural columns. It turned out that the irregularities of structural stiffness strongly influenced the dynamic behaviour of the object. The stiff concrete walls repeated the ground motion and moved like a rigid body. The dynamic response of the softer parts of structure, i.e. the floor slab and the concrete columns, reflected the natural modes of vibration connected with low frequencies rather than the ground movements. The higher frequencies occurring in the kinematic excitation were filtered out. To evaluate the influence of the roofing on the dynamic characteristics of the structure two variants of a numerical model were analysed: a model of the building with and without roofing. It occurred that in case of an irregular building with large roof area the inclusion of non-structural roofing elements is essential and may be of crucial importance while assessing the dynamic response of structure to seismic excitation. The negligence of these elements may result in unrecognizing of the resonance phenomenon.

Non-destructive identification of cracks in unilaterally accessible massive concrete walls in hydroelectric power plant

This paper presents a methodology for the non-destructive location and identification of cracks in unilaterally accessible massive concrete walls by means of the state-of-the-art acoustic methods of impulse response and ultrasound tomography. An example of the practical verification of the methodology used to investigate the concrete structure of a hydroelectric power plant is provided.

Influence of the Saturation Ratio on Concrete Behavior under Triaxial Compressive Loading

When a concrete structure is subjected to an impact, the material is subjected to high triaxial compressive stresses. Furthermore, the water saturation ratio in massive concrete structures may reach nearly 100% at the core, whereas the material dries quickly on the skin. The impact response of a massive concrete wall may thus depend on the state of water saturation in the material. This paper presents some triaxial tests performed at a maximum confining pressure of 600 MPa on concrete representative of a nuclear power plant containment building. Experimental results show the concrete constitutive behavior and its dependence on the water saturation ratio. It is observed that as the degree of saturation increases, a decrease in the volumetric strains as well as in the shear strength is observed. The coupled PRM constitutive model does not accurately reproduce the response of concrete specimens observed during the test. The differences between experimental and numerical results can be explained by both the influence of the saturation state of concrete and the effect of deviatoric stresses, which are not accurately taken into account. The PRM model was modified in order to improve the numerical prediction of concrete behavior under high stresses at various saturation states.

Application of air cooled pipes for reduction of early age cracking risk in a massive RC wall

The construction of massive concrete structures is often conditioned by the necessity of phasing casting operations in order to avoid excessive heat accumulation due to cement hydration. To accelerate construction and allow larger casting stages (usually increasing lift height), it is usual to adopt internal cooling strategies based on embedding water pipes into concrete, through which water is circulated to minimize temperature development. The present paper reports the use of horizontally placed ventilated prestressing ducts embedded in a massive concrete wall for the same purpose, in line with a preliminary Swedish proposal made in the 1990s. The application herein reported is a holistic approach to the problem under study, encompassing extensive laboratory characterization of the materials (including a technique developed for continuous monitoring of concrete E-modulus since casting), in situ monitoring of temperatures and strains, and 3D thermo-mechanical simulation using the finite element method. Based on the monitored/simulated results, it is concluded that the air-cooling system is feasible and can effectively reduce early cracking risk of concrete, provided adequate planning measures are taken.

Radon concentrations in different types of dwellings in Israel

The average radon concentration in Israeli dwellings was assessed by combining the results of a 2006 radon survey in single-family houses with the results of a 2011 radon survey in apartments of multistorey buildings. Both surveys were based on long-term measurements using CR-39 detectors. The survey in multistorey buildings was intended to assess the influence of recent practices in the local building industry on the radon concentrations. These practices include the use of building materials with higher concentrations of the natural radionuclides in the last 20 y than before, as well as the improvement in sealing techniques over that period. Another practice in place since the early 1990 s is the building of a shielded area in every apartment that is known as an RSS (residential secure space). The RSS is a room built from massive concrete walls, floor and ceiling that can be hermetically sealed and is intended to protect its residents from a missile attack. The influence of the above-mentioned features on radon concentrations was estimated by dividing the participating apartments into two groups: apartments in buildings >20 y, built using building materials with low concentrations of the natural radionuclides, regular sealing and without an RSS and apartments in buildings newer than 10 y, built using building materials with higher concentrations of the natural radionuclides, improved sealing and including an RSS. It was found that the average radon concentration in apartments in new buildings was significantly higher than in old buildings and the average radon concentration in single-family houses was significantly higher than in apartments in multistorey buildings. Doses due to indoor radon were estimated on the basis of the updated information included in the 2009 International Commission on Radiological Protection statement on radon.

Cracking analysis of massive concrete walls with cracking control techniques

This paper presents the results of a study on the cracking behaviour of young reinforced concrete walls with cracking control techniques. Material property tests were conducted to identify the time-dependent mechanical properties of the young concrete. A 1:4 scaled young reinforced concrete wall was tested up to 165days to identify the strain development of the concrete and reinforcing bars. A three-dimensional finite element model was developed and verified with consideration of concrete shrinkage, creep, cement hydration heat and variation of temperature. The model was used for cracking analysis of massive reinforced young concrete walls of a synchrotron radiation facility to identify the influence of concrete joints, construction sequence, concrete curing and external restraints. It was found that the concrete cracking can be mitigated by the proper use of concrete joints, a reasonable construction sequence, early age concrete curing and a loose external restraint.

Staging Resistance in Bil'in: The Performance of Violence in a Palestinian Village

Weekly confrontation between Palestinian villagers and the Israeli army in Bil'in is a ritual played out with such consistency and deliberation one cannot but note the performance on both sides. A closer look reveals a politics of oppression and a strategy of resistance that extend far beyond the massive concrete wall being built between them.

Numerical analysis of the early age behavior of concrete structures with a hydration based microplane model

To simulate the early age behavior of concrete structures composed of young concrete, a finite element analysis (FEA) was implemented with the hydration based microplane model. Structural behaviors were investigated with concrete age for a massive concrete wall and slab. From FEA, it was found that surface cracking at early age occurred via different crack driving mechanisms. In the case of combined hydration heat and shrinkage, later surface cracking was produced by differential drying shrinkage. A numerical analysis performed with the hydration based microplane model successfully simulated the typical cracking patterns due to edge restraint in the concrete slab.

Stability of ancient masonry towers: Moisture diffusion, carbonation and size effect

Moisture diffusion and carbonation influence the behavior of multiple-leaf ancient masonry walls, producing during centuries a redistribution of stresses from the core of lime mortar concrete to the external cladding of stiff masonry. This is likely one of the causes of long-time damage of some ancient masonry towers. With these motivations, coupled processes of moisture diffusion, carbon dioxide diffusion and carbonation reaction are analyzed numerically. Due to the absence of models and data for lime mortar, one of the simplest models proposed for Portland cement concrete is adapted for this purpose. The results reveal the time scales of the processes involved and their dependence on wall thickness (size). It is found that the temporal scale is set mainly by diffusion of moisture trough the massive concrete wall and is only slightly modified by carbonation. Moisture evolution in time is needed for stress analysis that is relegated to a subsequent paper.

Cohesive Fracturing and Stresses Caused by Hydration Heat in Massive Concrete Wall

Avoidance of cracking damage due to hydration is an important objective in the design of nuclear reactor containments. Assessment of the safety against cracking requires a realistic material model and its effective numerical implementation. Toward this goal, the paper develops a comprehensive material model which includes approximate simulation of cracking based on the principles of cohesive fracture mechanics, as well as an up-to-date creep formulation with aging and temperature effects. A standard heat conduction model is incorporated in the analysis as well. Since the crack width is the most important characteristic of cracking damage, particular attention is paid to crack spacing which governs crack width. The results of stability analysis of parallel crack systems based on fracture mechanics are used to estimate the spacing of open cracks as a function of their depth. Numerical simulations clarifying various aspects of hydration heat effects are presented.

Vertical Shear Loads on Nonmoving Walls. II: Applications

Massive concrete walls constructed on rock foundations, as well as other nonmoving retaining walls, are customarily designed for at-rest earth pressures. Vertical shear loads applied by the backfill are usually not considered in design of nonmoving walls, even though many field and laboratory measurements have shown that such loads exist. Vertical shear loads can be very beneficial for stability of retaining walls, because they provide restoring moments to counteract overturning moments from lateral earth loads. In this paper, model test results and case history data are reviewed, the results of finite-element calculations are presented, and a simple design procedure is developed. It is shown that significant economies can result from consideration of vertical shear forces in design of nonmoving retaining walls.