Geotechnical factors influencing earth retaining wall deformation during excavations

Mechanically stabilized earth (MSE) walls have gained significant popularity due to their economic advantages, ease of construction, and the wide array of proprietary systems available. These walls operate as gravity-retaining structures, relying on facing elements, compacted soil, and reinforcement working in conjunction. The reinforced-soil mass, formed by interlayered soil backfill and reinforcement, uses its self-weight to resist lateral pressures from various sources, including earth, surcharges from vehicles and buildings, seismic events, and water. A key benefit of MSE walls is their cost-effectiveness, often reducing expenses by 50 percent or more compared to conventional reinforced-concrete retaining structures, as highlighted by a 2001 USDOT and FHWA publication. Furthermore, their aesthetic appeal and straightforward construction methods, which don't necessitate highly specialized skills or equipment, contribute to their widespread adoption. While granular and free-draining select soil backfill is ideal, projects can utilize less desirable site soils if appropriate design and construction controls are implemented. Despite their advantages, MSE walls are susceptible to failure or performance issues, often stemming from common contributors such as the impact of civil site improvements, inadequate surface and subsurface water management, and poor project communication. Civil site improvements, particularly utility installations, pose significant challenges. Utilities, whether water-bearing (like drainage or pressurized waterlines) or non-water-bearing (like electrical conduits and gas lines), can be installed at various depths and locations relative to the wall, potentially affecting its performance. These installations can interfere with the soil reinforcing, leading to discontinuities. For instance, guardrails, utility manholes, and light poles might penetrate the reinforcing elements, causing damage or necessitating their removal, thereby reducing the wall's resistance to loads or introducing additional stresses. Such interferences are frequently overlooked during the design phase, requiring careful consideration from the MSE wall designer, civil site engineer, and contractor during construction. Water-bearing utilities are particularly problematic. If placed within or directly behind the reinforced fill, they can interrupt reinforcing and are prone to leakage over time. Severe leaks can lead to rapid hydrostatic or seepage pressure buildup behind the wall and erode the soil by transporting fine-grained particles through the mass. The wall designer must account for potential leakage and assess whether designing for water pressures is necessary to prevent structural issues. These considerations emphasize the critical need for comprehensive planning, design coordination, and effective communication among all project stakeholders to mitigate risks and ensure the long-term stability and performance of MSE walls. #BryanPStrohman #CivilEngineering #MechanicallyStabilizedEarthFoundationWalls #ReinforcedSoil #RetainingWall #ScottJDiFiore #WaterManagement

This study addresses the lack of comprehensive analyses and calculated examples for base shear seismic demand in heavy stone masonry buildings by examining nominally reinforced rubble stone masonry house and school designs commonly found in Nepal. The research applies seismic codes from countries where this construction technique is permitted (Nepal, India, China, Tajikistan, Iran, Croatia) or could be reintroduced (Pakistan, Afghanistan, Turkey). The initial phase of the study compares base shear formulas, inertia force distributions, material densities, seismic weights, seismic zoning, natural periods of vibration, response spectra, importance factors, and seismic load combinations across these codes, revealing significant discrepancies in approaches and coefficients. The research then calculates base shear and story shears for a design peak ground acceleration of 0.20g, along with the effects of critical load combinations on lateral-resisting elements, adhering to Equivalent Lateral Force (ELF) principles for Ultimate Limit State (ULS) verifications (10%PE50y). Pakistan's code is identified as the most lenient, Nepal's as an average, and India's and China's as the most conservative for the case study buildings. A key observation is that heavy-masonry-light-floor systems with negligible diaphragm action behave distinctly under seismic motion compared to other building typologies. The applicability of conventional ELF, S-ELF, and S-Modal methods for such heavy masonry buildings is questioned, as current codes do not offer modified approaches for these differences. Further assessment and validation are required for implications such as the exclusion of plinth masonry and large portions of seismic weight, necessitating potentially more sophisticated concepts like the equivalent frame method or distributed mass system. Considering Nepal's allowance of stone masonry in higher seismic hazard areas (>0.40g), in contrast to India (<0.12g) and China (<0.15g), Nepal's code serves as the reference for subsequent research aimed at verifying seismic demand through capacity checks of masonry piers and spandrels. The article highlights that these buildings, with heavy stiff walls and light flexible diaphragms, derive almost all their lateral-force-generating mass from the walls (approximately 97.5% versus 2.5% for diaphragms, including live loads). The choice of stone type significantly influences inertia forces, and current codes may underestimate base shear by excluding lower wall sections and lumping seismic weights at floor levels. Empirical formulas for the fundamental period (T1) can also lead to overestimation of maximum base shear in short-period buildings. The structural behavior factor, typically 2.0 for nominally reinforced stone masonry with cement mortar, is crucial, with values like Pakistan's R=4.5 potentially leading to underestimation. While many countries accept simplified analytical methods for regular structures, India's requirement for dynamic analysis at lower seismic levels seems inconsistent with non-engineered seismic design principles. Significant variations in seismic hazard levels and PGA values exist across the selected countries, with India and Tajikistan showing relatively low design accelerations not based on probabilistic approaches. Despite variations in coefficients, the resulting base shear for houses is similar across Nepal, India, Afghanistan (ELF), Iran, Turkey, and Croatia, with Nepal representing the average. Pakistan is the most tolerant, and China the most conservative in terms of base shear. When load combinations are applied, India's seismic demands become comparable to China's due to a high load combination factor. The study emphasizes the need for modified design approaches and rigorous validation of parameters specific to nominally reinforced stone masonry, advocating for global collaboration through initiatives like SMARTnet to improve seismic resilience in such structures globally. #RubbleStoneMasonry #SeismicDemand #SeismicCodes #BaseShear #LoadCombinations #EarthquakeEngineering #StructuralBehavior #BuildingDesign #HimalayanRegion

This study investigates the seismic performance of mid-rise and high-rise reinforced concrete (RC) buildings with unreinforced masonry (URM) infill walls containing various percentages of openings, considering the critical effects of soil–structure interaction (SSI). The research employs a soil–foundation–structure (SFS) modeling approach using the finite element software PLAXIS 3D, analyzing both a six-storey mid-rise and an eleven-storey high-rise RC building. The infill walls are modeled with opening percentages of 0% (fully infilled), 20%, 30%, and 40% to represent realistic door and window configurations, while also including a bare frame model for comparison. These building models are subjected to non-linear time–history analysis under bidirectional loading, simulating severe earthquake conditions from the 1995 Kobe earthquake, spectrally matched to Indian standards for seismic zone V. The analysis considers two distinct soil conditions: stiff (Type-B/medium) and soft (Type C) soils. The performance assessment parameters include maximum roof displacement, inter-storey drift ratio (ISDR), mode shapes, and damage state levels, determined using the HAZUS methodology. A key finding is that the inter-storey drift ratio significantly increases for all models under soft soil conditions, particularly for structures with 40% infill opening. The HAZUS damage assessment reveals that mid-rise buildings generally reach a moderate damage state, while high-rise buildings exhibit moderate-to-extensive damage with a 30% infill opening under both soft and stiff soil conditions. Notably, the study consistently shows that assuming fixed-base conditions significantly underestimates the actual storey damage state levels, highlighting the importance of incorporating SSI in seismic assessments. Mode shape analysis demonstrates that SSI considerably alters the lateral responses, increasing the dynamic time periods of the buildings. Buildings without infills (bare frames) are found to be highly vulnerable to SSI effects, experiencing large deformations. Conversely, fully infilled structures (0% opening) exhibit negligible lateral displacement, indicating that infill stiffness effectively resists deformation even with SSI. Structures on soft soil generally show enhanced deflection compared to those on stiff soil, further emphasizing the impact of soil flexibility. Regarding lateral displacement, both absolute maximum roof displacement and relative displacement are higher in soft soil conditions than in stiff soil. For instance, mid-rise structures on soft soil show relative displacement amplifications of up to 25.6% for certain infill configurations compared to stiff soil. Similarly, high-rise structures on soft soil show substantial amplifications, with the M4H model on stiff soil displaying 31.3% higher lateral displacement than a fixed-base counterpart. The varying infill opening percentages also influence these displacements, with larger openings generally leading to increased structural movements. Analysis of shear force and bending moments indicates that infill walls with openings, particularly those with 40% opening, experience higher concentrations of these forces near edges and openings. These concentrations suggest potential vulnerabilities to diagonal cracks or shear failure. The presence of openings modifies load paths, making structures more susceptible to localized damage, while soft soil conditions further amplify structural movements and twisting, increasing the likelihood of shear and bending failures in infills. Torsional moments are also significantly observed in models with openings, especially along the corners, and are more pronounced in soft soil due to increased flexibility. The study concludes that optimal infill opening percentages are highly dependent on soil type and building height. Under stiff soil conditions, optimal opening percentages are estimated to be 40% for mid-rise buildings and 30% for high-rise buildings. However, these optimal percentages are significantly reduced to 30% and 20%, respectively, under soft soil conditions. The findings underscore the critical need for SFS modeling in seismic assessments, particularly for URM-infilled buildings in seismically active regions, to accurately predict structural behavior and optimize infill opening designs. The performance assessment parameters utilized in this research are deemed satisfactory for achieving this optimization. #SeismicPerformance #ReinforcedConcreteBuildings #UnreinforcedMasonryInfill #InfillOpenings #SoilStructureInteraction #PLAXIS3D #NonLinearTimeHistoryAnalysis #DamageAssessment #InterStoreyDriftRatio

This literature review examines the state of the art concerning non-engineered rubble stone masonry construction, specifically for school buildings, in seismic areas. The research focuses on structures built with loadbearing walls of rubble stone masonry in cement mortar, reinforced with horizontal elements. A total of 47 relevant field manuals published between 1972 and 2017 were analyzed, alongside 109 national building codes. The objective was to identify similarities, contradictions, gaps, and discrepancies among these publications. Given that most practical manuals target the Himalayan context, Indian and Nepali seismic and building codes were particularly relevant for comparison. A significant finding is that only nine manuals provide design and construction processes for schools, despite these often conflicting with codes that explicitly prohibit stone masonry for buildings with an importance factor of 1.5 or higher (which includes schools). It was observed that seven of these nine manuals were either written or co-written by the same author, Martijn Schildkamp, and that much of the available knowledge, largely empirical, stems from a limited number of primary sources. However, consistency and consensus were lacking across almost all critical topics, such as main dimensions, opening parameters, and reinforcing elements. Furthermore, the persistent copying of identical illustrations and tables, including those with apparent conflicts, suggests that knowledge in this domain has not significantly advanced since the 1980s, an observation reinforced by the fact that Indian and Nepali seismic codes have not been substantially updated since 1994. The review highlights that existing information contains numerous contradictions and has become ambiguous, raising concerns about its correctness, reliability, and practical value. For instance, while Indian codes prohibit low-strength masonry for important buildings (like schools) in high seismic zones, the Nepali government has approved school designs in rubble stone masonry, directly contradicting its own regulations. The authors propose that the current body of knowledge requires comprehensive assessment, validation, optimization, and supplementation through modern computational, testing, and modeling techniques. To address this, the authors have launched the SMARTnet initiative (Seismic Methodologies for Applied Research and Testing of non-engineered Techniques), which aims to update and disseminate knowledge about traditional building techniques, starting with rubble stone schools in Nepal as a case study. This initiative calls for global collaboration from experts and academics. The paper details the specific design parameters of schools built by the Smart Shelter Foundation in Nepal, which largely withstood the 2015 Gorkha earthquakes. These designs feature maximum classroom dimensions of 4.8 x 4.8 meters, 350mm thick random rubble stone masonry walls with cement-sand mortar, buttresses at wall ends, and horizontal reinforced concrete bands at five levels. The decision not to include vertical reinforcements in critical wall connections, based on expert advice regarding potential weakening, remains a debated topic. The type of stone masonry and mortar is also discussed, categorizing stone types (rubble vs. ashlar) and mortar compositions (mud, cement, lime-sand) in relation to seismic safety. Rubble stone masonry with cement mortar is classified as the second safety level according to Arya (2003). Additionally, the paper distinguishes between reinforced, confined, and unreinforced masonry systems, noting the ambiguity in classifying structures with minimal reinforcement. It discusses the concept of "non-engineered" construction and the historical development of guidelines for such buildings, highlighting the need for separate code specifications for engineered and non-engineered structures. The article also examines how building categories are determined, referencing seismic zonation, ground conditions, and building importance, and critically assesses the "one-size-fits-all" approach in some publications. The eligibility of national seismic codes is narrowed down to the Himalayan region due to global restrictions on rubble stone masonry in high seismic zones and linguistic challenges. For practical manuals, a completeness analysis revealed that only one manual fully aligned with the specific search criteria, emphasizing the scarcity of precise and comprehensive guidance for this construction type. #RubbleStoneMasonry #SeismicCodes #NonEngineeredConstruction #SchoolBuildings #EarthquakeEngineering #BuildingManuals #HimalayanRegion #ConstructionSafety #StructuralIntegrity

Rammed earth construction, an ancient technique originating independently in China and the Iberian Peninsula several thousand years ago, is gaining recognition for its numerous green building benefits. This method, utilized in structures like the Hakka Tulou in China and the Alhambra Palace in Spain, offers low embodied energy, recyclability, high thermal mass, low energy loads, and non-toxicity. Terrell Wong, principal of Stone’s Throw Design Inc. in Ontario, Canada, advocates for rammed earth, highlighting its durability and longevity, asserting that a rammed earth house can last 500 years or more without needing paint. Rammed earth walls are constructed in approximately 11.5 ft. panels with flexible joints. The material mix typically includes 20% to 30% clay, sand, and 5% to 10% cement for added strength, with silicate-based waterproofing sometimes incorporated for cold, wet climates. The process involves layering a foot of material into formwork, which is then compressed to 6 inches using a pneumatic tamper. The forms, usually made from Marine-grade plywood and 2x12 walers, are about 20 inches wide and 4 feet tall. For multi-panel walls, a recess on the first panel locks with the second. Conduits for plumbing and electrical wiring are integrated during construction, requiring precise planning as changes are impossible once the wall is set. Walls typically dry within 24 hours and possess a load-bearing capacity comparable to concrete. Despite its ancient origins and proven effectiveness, rammed earth construction remains a niche method in North America. Terrell Wong designs three to four rammed earth houses annually, noting only a handful of builders in Ontario specialize in this technique. Sylvia Cook of Aerecura Rammed Earth Builders emphasizes that the method's thermal mass benefits apply universally, delaying heat gain in hot climates and shifting heat loss in cold climates to periods when solar gain can compensate, thus maintaining consistent indoor temperatures. The limited adoption is primarily attributed to a lack of public and professional knowledge about the system’s versatility across different climates. The distinctive earthy-toned striations characteristic of rammed earth walls are achieved by adding pigment to the cement mix. The ramming process pushes the colors to the formwork edges, creating a natural gradation. Exaggerating the undulations in the formwork can enhance these visual effects. While modern rammed earth construction has advanced, North America lacks specific building codes for it, unlike Australia and New Zealand where codes are formalized, and research even suggests superior seismic resistance compared to brick or block walls. In Canada, builders obtain approval by demonstrating that rammed earth meets existing code requirements, similar to concrete. In colder regions like Ontario, fiberglass rebar is used for structural stability, and recycled polyiso insulation is often integrated into the walls to minimize thermal bridging. The cost of rammed earth projects is influenced by design complexity, with curved or angled walls being more expensive due to the labor-intensive nature of the method. However, by simplifying design and formwork, Terrell Wong successfully applied the technique to an affordable housing project meeting Passive House standards. Many rammed earth homes are hybrids, incorporating elements like stick- or timber-frame walls for interior partitions or upper floors, sometimes combined with straw-bale construction or CLT-panel roofs. The featured single-family home, situated in a rural Ontario subdivision, exemplifies the integration of rammed earth with Passive House strategies. The design maximizes thermal mass, harvests southern light, and utilizes cross breezes to enhance passive ventilation, eliminating the need for mechanical cooling. The home's heating demand is approximately 20 kWh/m2 annually. The exterior walls consist of 530 tons of thermal mass, comprising two 6-inch rammed earth wythes around 6 inches of insulation. The construction’s embodied energy is exceptionally low, as 90% of the unprocessed material was sourced from a nearby gravel pit, and salvaged wood from a local roundhouse was repurposed for the main stair. #RammedEarthConstruction #SustainableBuilding #GreenBuilding #ThermalMass #PassiveHouse #BuildingMaterials #EcoFriendlyHomes #ArchitecturalDesign #CanadianArchitecture

The Himalayan region of Nepal, characterized by ongoing neo-tectonic activities, is highly vulnerable to seismic events. Stone masonry, often constructed with or without mud mortar, has been the primary building material for centuries. A significant structural survey of approximately 223 buildings in three remote rural villages revealed prevalent structural irregularities, such as variations in wall thickness between floors leading to mass irregularities, asymmetrical vertical openings causing in-plane discontinuity, and out-of-plane offset irregularities due to cross walls on the ground floor. These constructions were typically built without seismic considerations, making them highly susceptible to earthquake damage, as evidenced by the 2015 Gorkha earthquake. This study examines a typical building, incorporating construction information gathered post-2015 Gorkha earthquake, to enhance seismic design based on local construction practices. The use of mud/cement mortar was minimal in these traditional structures. Timber bands at various wall heights and appropriate roof-to-wall connections were also largely absent. Following the 2015 earthquake, communities implemented several improvements, including replacing gable walls with metal sheets, reducing individual stone masonry homes to a single story, and using lighter construction for the upper stories of hotel buildings. The study emphasizes the potential for seismically resilient building forms by meticulously detailing the construction of these structures using mud/cement mortar and other regional materials. Non-linear finite models were simulated for both typical and enhanced buildings, based on regional building techniques. The inherent irregularities of stone units, construction variability, and constrained linear behavior present challenges for detailed numerical analysis of stone masonry with and without mud mortar. Traditional Sherpa homes, characterized by their elongated shape and strategic placement parallel to hill slopes, often feature thick outer protective walls of locally available stone, reaching up to 1 meter in thickness. These are usually unshaped rubble plastered with yak dung and mud mixture. An internal timber frame supports a wooden ceiling. Older, simpler rubble-built houses often lack horizontal timber beams integrated into the outer stone walls, a feature that would enhance earthquake resistance. Foundations and floors are typically stone, with houses being single or two stories. Two-story homes historically used the ground floor for livestock and storage, with living areas upstairs. The 2015 Gorkha earthquake severely damaged 93% of traditional houses and tourist structures in the Thame Valley, with 66% completely damaged. Observed damage patterns included 'X cracking' of external walls, stones toppling from wall tops and roof triangles, and subvertical cracks. Out-of-plane failure of long, thick stone masonry walls was common due to the absence of cross walls and seismic bands, indicating a lack of lateral load resistance and proper roof-to-wall connections. The construction of dry stone stacks with external pointing and plastering contributed to individual masonry unit failure rather than cohesive wall strength. Post-earthquake reconstruction, often carried out by the community with some government support, did not always incorporate seismic-resistant designs due to the urgency. A rapid visual screening (RVS) in August 2022 confirmed that 92% of buildings were stone masonry, with 43% being uncoursed random rubble. Only 2% of buildings used cement mortar, primarily schools and monasteries, while less than 1% used mud mortar. About 88% of buildings now have CGI metal sheet roofing, replacing heavier slate roofs. While corner tie stones are still common (68%), less than 5% and 2% of buildings had timber and reinforced concrete bands, respectively. A significant change was the replacement of stone masonry gable walls with lightweight metal CGI sheets in 43% of buildings. The majority (72%) of reconstructed individual homes are now single-story, with separate structures for animals and storage, reflecting community-learned adjustments. The study concludes that while the introduction of timber bands and wall buttresses (Enhanced-Irregular Stone Masonry Building, E-ISMB) significantly improved building performance under lateral loading, a more comprehensive approach to incorporating additional enhancement techniques is required. Numerical analysis showed that E-ISMB had a fundamental time period reduced by 28.2% and lateral strength increased by 73.5% compared to Current-Irregular Stone Masonry Building (C-ISMB), indicating enhanced rigidity and capacity. Cross walls, buttress walls, and timber bands, in conjunction with mud mortar, can effectively reduce out-of-plane deformation and distribute stresses more uniformly, thus delaying collapse and improving overall seismic performance. Further numerical and experimental studies are needed to fully understand the local failure modes and optimize additional recommended enhancement techniques. #HimalayanBuildings #SeismicDesign #StoneMasonry #EarthquakeResistance #NepalArchitecture #StructuralIrregularities #PostEarthquakeReconstruction #ResilientDesign

Keystone Retaining Wall Systems LLC has released updated versions of its construction manuals and introduced a new Design Manual & KeyWallPRO Operating Guide. These resources are specifically designed for professionals involved in the construction of gravity and reinforced segmental retaining walls. The comprehensive guides aim to provide detailed information and practical support for various aspects of retaining wall projects. The Keystone Construction Manual offers extensive guidance on the design, technical considerations, estimating processes, and installation guidelines for gravity and reinforced segmental retaining walls. This manual focuses on the use of Keystone Standard and Keystone Compac units, providing users with the necessary knowledge to execute these types of constructions effectively. The content covers foundational principles and best practices for building durable and structurally sound retaining walls. In addition to the standard construction manual, an updated version of the Keystone Construction Manual is now available in both English and Spanish. This version specifically addresses the installation of gravity and reinforced segmental retaining walls constructed with Keystone Regal Stone Pro units. The Regal Stone Pro system is noted for its rear-lip design, which facilitates accurate setback alignment and simplifies the installation process. The inclusion of both languages makes this vital information accessible to a broader range of construction professionals. The newly introduced Keystone Design Manual & KeyWallPRO Operating Guide provides a methodical framework for understanding the design theory, overall process, and construction of gravity and reinforced segmental retaining walls. A key feature of this guide is its integration with the proprietary KeyWallPRO design software. This software is instrumental in assisting users with complex design calculations and simulations, enhancing the precision and efficiency of project planning. The manual offers technical insights and step-by-step instructions, catering to both experienced engineers and those new to the KeyWallPRO software. It incorporates numerous charts and diagrams, which are crucial for determining appropriate design heights and specifying geogrid reinforcement. This detailed visual aid helps in simplifying complex calculations and ensures accuracy in material selection and placement. The guidance extends to various project complexities, from standard wall constructions to more specialized applications, including water features, drainage systems, barrier installations, and terraced wall designs. This breadth of coverage ensures that the manual is a valuable resource for a wide array of retaining wall projects. All updated resources, including the digital versions of the manuals and other technical installation tools, are readily available online through the Keystone Retaining Wall Systems website. Users can access these materials at www.keystonewalls.com/resources/design-construction-manuals. For those who prefer physical copies or need further information, all Keystone resources can be requested electronically or in hard copy by visiting www.keystonewalls.com/request-information. These resources are intended to empower construction professionals with the tools and knowledge required to achieve high-quality and reliable retaining wall constructions. #KeystoneRetainingWallSystems #ConstructionManuals #KeyWallPRO #RetainingWallDesign #SegmentalRetainingWalls #GeogridReinforcement #ConstructionResources #TechnicalGuidance

This article presents an interview with Kyle Tourjé, Executive Vice President of Alpha Structural Inc., focusing on the critical aspects of concrete foundation repair and seismic retrofitting, particularly in earthquake-prone regions like Southern California. Alpha Structural Inc., a second-generation company, offers comprehensive civil and structural engineering services, alongside licensed general engineering and concrete specialty contracting. Their expertise spans structural concrete, geohazard repair, and various seismic retrofits, including coastal and hillside repairs, structural steel and concrete repairs, foundation replacement, landslide remediation, slope stabilization, deep foundation systems, and retaining walls. The company integrates both engineering and construction disciplines to ensure a seamless project execution from design to completion. Tourjé highlights geology-related issues as the most common causes of concrete foundation problems, where substandard bearing materials often lead to settlement and instability. Corrosion-related damage is another significant factor, causing deterioration in concrete structures, along with poor drainage which accelerates the overall degradation of foundations over time. He emphasizes the importance of collaboration between structural engineers and concrete contractors, advocating for contractor input during the engineering design phase to enhance constructibility and prevent project delays, performance issues, or disagreements. This integrated approach ensures that practical construction considerations are factored into the theoretical design. In Southern California, specific construction practices are implemented to resist seismic forces, which are often not mandated in other states. These practices include the precise placement of reinforcing steel, the use of high-strength concrete mixes, and meticulous rebar installation to prevent corrosion and ensure long-term foundation resilience. Key details such as maintaining adequate clearance between reinforcing steel and the concrete surface are critical, underscoring that cutting corners on these installation steps can compromise structural integrity. Contractors in other regions can learn from these practices, particularly focusing on preventing corrosion by ensuring correct concrete slump and proper rebar placement. Recent updates in ACI documents and committees relevant to concrete foundation placement in seismic areas include clarifications to seismic design criteria, new maximum stirrup spacing for closed stirrups under seismic demand, and updated seismic design requirements for deep foundations across all categories. These changes are crucial for adhering to the latest safety and durability standards in earthquake-prone zones. Emerging technologies and trends in concrete construction include pressure-injected concrete, advanced mix designs for improved corrosion resistance and strength, and the application of fiber-reinforced polymer (FRP) as an alternative to traditional steel rebar. These innovations contribute to building stronger and more durable foundations. Tourjé advises concrete contractors to remain committed to quality, especially during challenging project phases, and to strive for perfection in every pour to deliver work that meets the highest standards. #ConcreteConstruction #SeismicRetrofitting #FoundationRepair #StructuralEngineering #ConstructionTechnology #EarthquakeResilience #CorrosionPrevention #ConstructionBestPractices #SouthernCalifornia

The widespread use of rubble stone masonry, particularly with cement mortar and wooden diaphragms, in seismic regions globally necessitates a comprehensive review of existing design specifications and construction requirements outlined in national seismic and masonry codes. This analysis covers nearly 325 codes from countries where this building technique is, or has been, common. The review focuses on identifying the allowances, restrictions, and specific details related to newly constructed houses and schools using "nominally reinforced rubble stone masonry (NRM) with cement mortar and wooden diaphragms in seismic areas." This particular type of construction is specifically detailed and permitted in the codes of only seven countries: Nepal, India, China, Tajikistan, Georgia, Iran, and Croatia. Significant inconsistencies are observed among these national codes regarding design specifications. Parameters such as maximum building dimensions (length, width, and height), minimum and maximum wall and opening dimensions, and specifications for horizontal and vertical reinforcements vary considerably. For instance, maximum building lengths between seismic gaps range from 25m in Iran to 80m in Georgia, and the number of allowed stories ranges from one to five, even for similar design accelerations. Reinforcement requirements also differ widely, with some codes mandating multiple horizontal and vertical reinforcements, while others require only a few horizontal tie-beams. The discrepancy extends to maximum allowed design accelerations, which range from 0.08g in Indian zone III to 0.52g in Georgia. Such wide variations raise concerns about the completeness, correctness, and reliability of the current knowledge base in this field. Another critical observation is the lack of clear descriptions regarding the types of stone masonry and stone properties addressed in many codes. Often, codes fail to distinguish between random rubble and cut, dimensioned stones, leading to ambiguity and potential misinterpretation. This is particularly prevalent in former Soviet countries whose codes are based on outdated clauses for dimensioned tuff stones, despite rubble stone being the prevalent local material. Furthermore, many codes use vague language, such as "should preferably be avoided," which weakens mandatory compliance. To address these issues, the introduction of "Nominally Reinforced Masonry" (NRM) as a distinct, fourth category of masonry, alongside Unreinforced Masonry (URM), Confined Masonry (CM), and Reinforced Masonry (RM), is proposed to provide clearer terminology and avoid confusion. It is also recommended that codes explicitly state whether rubble stone masonry is permitted, specifying the types of buildings and structures to which it applies. Moreover, the study highlights that many countries where stone masonry is still a widely practiced technique, such as Afghanistan, Pakistan, Bhutan, Azerbaijan, Kyrgyzstan, Morocco, Tunisia, Turkey, Yemen, and Albania, either prohibit it in their codes or lack relevant regulations entirely. This disparity between traditional construction practices and formal building codes creates a significant challenge for local builders and communities. The paper advocates for the development of a stand-alone code specifically for NRM rubble stone buildings with cement mortar, consolidating all necessary design and execution information into a single, accessible document. Such a code would prevent the interchanging of incompatible specifications meant for other masonry types. This comprehensive review forms the basis for future research within the "SMARTnet" initiative (Seismic Methodologies for Applied Research and Testing of Non-Engineered Techniques). This initiative aims to assess, validate, optimize, and complement existing knowledge through modern calculation, testing, and modeling methods. The goal is to develop a structured research approach, termed "Non-Engineered 2.0," focused on vernacular and traditional construction techniques to improve the seismic resilience of rubble stone masonry buildings globally. This effort is crucial for providing clear, reliable, and up-to-date information to millions of people who reside in stone houses worldwide, ultimately strengthening confidence in this traditional building method and potentially reintroducing it where it is currently prohibited. #RubbleStoneMasonry #SeismicCodes #MasonryDesign #EarthquakeEngineering #BuildingCodesWorldwide #NominallyReinforcedMasonry #TraditionalConstruction #SustainableDesign #BuildingResilience

This paper presents a detailed cost analysis of earthquake-resistant school buildings in the Kaski District of Nepal, specifically those constructed by the Smart Shelter Foundation (SSF) between 2007 and 2017. The study compares three primary designs: rubble stone masonry with a wooden roof, and concrete block masonry with either a wooden or a steel trussed roof. The analysis is based on a unique dataset of local building prices collected from 19 different villages, alongside general District Rates, spanning a decade. The cost breakdown is meticulously segmented into five main construction phases—foundation, walls, roof, floor, and finishing—and further categorized into materials, labor, and transportation costs. The research addresses several key questions, including the impact of materials and construction phases on overall costs, the economic viability of rubble stone versus concrete block masonry, cost implications of alternative foundation, wall, and roofing solutions, the effect of the 2015 Gorkha Earthquakes on construction costs, and the cost difference between traditional unreinforced school buildings and fully reinforced seismic designs. Master designs with consistent dimensions were prepared for fair comparisons, and master estimates were developed considering local contextual factors such as material prices and labor wages. These local rates were then contrasted with the official District Rates to identify discrepancies and general cost distribution patterns. The study reveals significant fluctuations in market prices, particularly for locally sourced materials, which complicate the detection of consistent patterns for future predictions. No clear similarities were found between local village rates and general District Rates, indicating that official rates often fail to capture micro-level variations like material availability, site accessibility, and local preferences. To aid future estimations, the paper introduces a tool for rapid cost estimation of different school designs. The cost distribution across main construction phases varied significantly over the 10-year period, with the proportion for labor increasing and transportation costs decreasing, possibly due to improved road networks. In 2017, steel roofs emerged as the most economical option across all three construction groups, contrasting with earlier periods where wooden roofs were often cheaper in certain areas. A specific analysis of seismic features indicates that while improving masonry with cement mortar has the most substantial cost impact, incorporating essential seismic elements such as horizontal bands, buttresses, and steel bars is not prohibitively expensive. The cost of adding two continuous horizontal beams, for instance, is a minimal increase, suggesting that financial constraints are not a major barrier to implementing these safety measures in new constructions. The paper also simulates the transformation of a traditional unreinforced building into a fully reinforced school, demonstrating that seismic improvements contribute significantly to the total cost, but non-structural elements like flooring and finishing can be even more costly, primarily due to labor intensity. The findings suggest that despite some expectations of dramatic price surges after the 2015 Gorkha Earthquakes, the actual increases in Kaski and Gorkha Districts were more moderate, particularly when compared to previous claims of doubling or tripling prices. The paper concludes by providing Bills of Quantity (BoQ) for various school types, offering a practical framework for villagers to compare construction costs based on local prices. It emphasizes that while cost is a major factor, local customs, material availability, and accessibility also play crucial roles in construction choices. The authors advocate for further interdisciplinary research and collaboration to validate and optimize traditional building techniques for seismic resilience, an initiative launched under the name SMARTnet. #EarthquakeEngineering #CostAnalysis #RubbleStoneMasonry #ConcreteBlockMasonry #SeismicResilience #NepalConstruction #BuildingMaterials #ConstructionManagement #SustainableDesign

The Ladakh region, situated high in the Himalayan Mountains, is characterized by its remote location, extreme climate, and a short construction season of only four to six months. Temperatures fluctuate dramatically, reaching +30 degrees Celsius in summer and dropping to -30 degrees Celsius in winter. These harsh conditions necessitate robust construction methods, but importing materials is often impractical and expensive due to the region's inaccessibility. Czech architecture firm Archide addressed this challenge by revitalizing the use of rammed earth, a locally abundant material, for construction in Ladakh. Rammed earth construction leverages local soil, making it a sustainable and cost-effective solution for remote areas. The process involves compacting layers of damp soil into formwork, which then cures to create durable, monolithic walls. This method is particularly well-suited for the Himalayan climate because earth walls possess excellent thermal mass properties, meaning they can absorb and store heat during the day and release it slowly at night. This natural insulation helps maintain stable indoor temperatures, reducing the need for artificial heating and cooling in a region with severe temperature swings. Beyond its thermal advantages, rammed earth is environmentally friendly. It minimizes transportation costs and associated carbon emissions, as the primary material is sourced directly from the construction site or nearby. This reduces the ecological footprint of building projects. Additionally, rammed earth is non-toxic and breathable, contributing to healthier indoor air quality compared to many modern building materials. Its inherent durability also means structures built with rammed earth can last for centuries, reducing the need for frequent repairs or replacements. Archide's project in Ladakh demonstrates a successful blend of traditional building techniques with modern architectural principles. By adapting and refining rammed earth construction, they have provided the local communities with resilient and comfortable living spaces that are harmoniously integrated with the natural environment. This approach not only addresses immediate housing needs but also preserves cultural heritage by continuing the use of vernacular materials and construction knowledge. The revival of rammed earth in the Himalayas serves as a model for sustainable development in other remote and climatically challenging regions, showcasing how readily available resources can be harnessed for practical, durable, and eco-conscious construction. #RammedEarth #HimalayanArchitecture #SustainableBuilding #VernacularArchitecture #PassiveDesign #Archide #LadakhConstruction #EcoFriendlyMaterials

Rammed earth, an ancient construction method, continues to offer significant potential for contemporary earth architecture, particularly regarding its aesthetic qualities. The unique visual characteristic of rammed earth walls, a layered appearance, emerges as formworks are removed, revealing horizontal stratifications of earth tones, varied material content, and nuances from the curing process. This distinctive aesthetic can be intentionally manipulated and enhanced through thoughtful consideration of patterns, textures, pigmentation, and the inherent colors of natural clays. This approach allows architects and designers to expand the creative boundaries of rammed earth in architectural applications. The aesthetic potential of rammed earth walls is deeply rooted in the geological composition of the earth used. The natural color of the clay and aggregates within the earth mixture determines the fundamental hue of the wall. Variations in mineral content, such as iron oxides, manganese, and organic matter, contribute to a diverse palette of natural colors, ranging from reds and browns to yellows and greys. Understanding these natural variations is crucial for predicting and designing the final appearance of the wall. Beyond natural variations, pigmentation offers a direct means of controlling and expanding the color range. Introducing natural or synthetic pigments into the earth mixture can produce a wide spectrum of colors, from subtle enhancements of natural tones to vibrant and bold statements. The amount and type of pigment, along with its dispersion within the mix, directly influence the intensity and uniformity of the resulting color. The layered compression process inherently creates patterns within rammed earth walls. Each layer, compacted individually, can differ slightly in material composition, moisture content, or compaction pressure, leading to visible horizontal striations. These layers can be intentionally varied to create distinct patterns, such as alternating colors or textures, introducing a dynamic visual element. The texture of a rammed earth wall is influenced by the aggregate size, the compaction method, and the final finishing. A rougher texture can highlight the material's earthy quality, while finer aggregates and smoother compaction can result in a more refined surface. Both patterns and textures contribute to the tactile and visual richness of the walls. Exploring the interplay between natural clay colors and pigmentation requires a deep understanding of material science and artistic vision. For example, some projects might leverage the subtle beauty of local earth, allowing its natural variations to dictate the aesthetic. In contrast, others might use pigmentation to achieve a specific brand identity or to integrate the structure with a predetermined color scheme. Careful experimentation and mock-ups are essential to predict the final appearance, as the color of dry rammed earth can differ significantly from its wet mixture. The curing process also plays a role, as moisture evaporation and chemical reactions can slightly alter the final tone. By skillfully combining the inherent beauty of natural earth with controlled pigmentation and intentional layering, the aesthetic versatility of rammed earth construction can be fully realized, providing a sustainable and visually compelling building material. #RammedEarth #NaturalClayColors #Pigmentation #EarthConstruction #SustainableArchitecture #MaterialDesign #ArchitecturalAesthetics #BuildingMaterials #Clayworks

The article discusses the critical differences between dampproofing and waterproofing foundation walls, emphasizing that preventing water intrusion from the exterior is generally more effective and economical than interior solutions. Homeowners' expectations for basements have evolved from simple storage areas to finished living spaces, making robust moisture control more important than ever. While the International Residential Code (IRC) mandates dampproofing, this primarily addresses liquid water not under hydrostatic pressure, using materials like bituminous coatings. These coatings are common and cost-effective but cannot span cracks or withstand hydrostatic pressure, which is why they are not considered full waterproofing. Waterproofing, on the other hand, is necessary in areas with high water tables or significant rainfall, and it involves materials designed to resist hydrostatic pressure. These include liquid-applied membranes (like styrene-butadiene rubber compounds) and peel-and-stick sheet membranes. Liquid-applied options offer seamless coverage but depend on consistent application, while sheet membranes require careful detailing of seams. Both types are often applied over primers, and some can be used in low temperatures. It is important to note that for a basement to be truly watertight, a waterproofing layer should also be applied beneath the slab to prevent water from being forced up through the floor by hydrostatic pressure. The article outlines a 'good-better-best' approach to foundation protection, starting with a basic dampproofing layer combined with a drainage membrane (like a dimple mat) and perimeter drains for capillary breaks and vapor barriers. A more advanced level adds a dampproofing layer, a dimple mat, and drainage at the wall's base, with the membrane's top edge sealed to the foundation. For the most challenging conditions or sensitive interior spaces, a multi-layered system is recommended, comprising a dampproofing layer, a dimple sheet for an air gap, and a drainage sheet with geotextile, all directing water to perimeter drains. These perimeter drains, installed below the basement floor level, are crucial in all scenarios. Various professionals integrate multiple layers for enhanced protection. For example, some builders use a liquid-applied or peel-and-stick membrane directly on the foundation wall, sealing joints and voids, followed by an insulation layer, and then a drain board with an integral air gap to protect the waterproofing and relieve hydrostatic pressure. Perimeter drains filled with coarse gravel and filter fabric complete the system. Other waterproofing materials include flexible cementitious coatings and bentonite panels, which expand when wet to create a seal, though their effectiveness can be compromised by repetitive wetting and drying cycles. Thermofusible membranes, requiring skilled application with heat, offer complete coverage but are less common due to complexity and safety concerns. Addressing leaks in existing foundations, or retrofits, presents additional challenges. Before undertaking major structural work, assessing site grading, gutters, and downspouts to redirect rainwater away from the foundation is advised. For minor cracks, external spot repairs with bentonite or internal epoxy/urethane injections can be effective. More extensive internal repairs may involve cutting the concrete slab to install interior perimeter drains and sump pumps, combined with internal drainage layers. However, this approach carries the risk of creating pathways for radon gas, necessitating airtight and vapor-tight seals. Interior coatings like UGL Drylok, Koster NB1 Grey, and Xypex Concentrate are also discussed, with testing indicating varying degrees of effectiveness against hydrostatic pressure and the importance of proper application and curing. The article concludes by stressing that investing in comprehensive waterproofing during new construction is a wise insurance against future water problems, especially given the increased use of basements as finished living spaces. #FoundationWalls #Dampproofing #Waterproofing #BasementProtection #MoistureControl #BuildingScience #ConstructionMaterials #HomeBuilding #RetrofitSolutions

In regions characterized by low to moderate seismic activity, such as Switzerland, structures that combine reinforced concrete (RC) and unreinforced masonry (URM) walls are prevalent. Despite their commonality, a comprehensive understanding of their seismic performance remains elusive. The structural integrity of these mixed RC-URM buildings is significantly influenced by both types of walls, given that their stiffness and strength are often comparable. This research project aims to deepen the understanding of the seismic behavior of buildings incorporating both RC and URM walls. A key objective is to formulate performance-based seismic design guidelines specifically tailored for these structures. This includes establishing clear definitions for various performance limit states that these buildings should meet under seismic loading. Additionally, the project focuses on the out-of-plane response of URM walls within these composite structures, investigating how boundary conditions provided by slabs and adjacent walls affect their behavior. The research methodology involves two extensive large-scale testing programs. The first program entails quasi-static cyclic tests conducted on systems comprising one RC wall and one URM wall. These tests are designed to simulate the cyclic loading experienced during an earthquake and to observe the structural response. The second program, known as the CoMa-WallS Project, involves shake table tests on a four-story building constructed at half-scale, integrating both RC and URM walls. This larger-scale test allows for a more realistic assessment of the overall structural performance under dynamic seismic excitation. The project has already yielded significant insights, including the publication of an article on quasi-static cyclic tests of two mixed reinforced concrete–unreinforced masonry wall structures. A dataset associated with this research is also publicly available. The project has received funding from several sources, including the Federal Office for the Environment, the FP7 program for access to the TREES laboratory of EUCENTRE under a specific grant agreement, and in-kind contributions from Morandi Frères SA. Ultimately, the findings from this research are intended to improve the seismic resilience of mixed RC-URM structures. By providing a better understanding of their behavior and developing robust design guidelines, the project contributes to enhancing the safety and performance of these common building types in earthquake-prone areas, ensuring they can withstand seismic events effectively and minimize damage and risk to occupants. #SeismicBehavior #ReinforcedConcrete #UnreinforcedMasonry #StructuralEngineering #EarthquakeResilience #PerformanceBasedDesign #ShakeTableTests #BuildingStructures

Floating walls are a crucial structural solution in construction, particularly in areas with challenging soil conditions. These walls address the problem of soil expansion and contraction, which can significantly impact concrete foundations. When heavy rains or freezing ground cause the soil beneath a basement to swell, it can lead to ground heave, exerting immense pressure on a building's structure. In regions characterized by heavy clay soils, framing floating walls creates a necessary gap that relieves this pressure, preventing damage to the home's joists and other structural components. This method is essential for maintaining structural integrity and avoiding issues such as cracked tiles and buckled wood flooring. Carmine Argano, owner of Creative Design Ceramic Tile & Bath, highlights that floating walls are specifically designed to accommodate movement in a concrete slab. This movement can arise from expansive soil, seismic activity, or frost heave. A rigid wall frame in such conditions would transfer any slab lift directly into the floor system above, leading to extensive damage. The typical approach to building a floating wall involves leaving a 3-inch gap between the base of the wall frame and the bottom of the framed wall. This gap allows the bottom plate to slide slightly on the nails if the slab shifts upward, preventing the pressure from being transferred to the rest of the structure. While this system provides crucial movement tolerance, Argano notes that it does result in a slight loss of rigidity compared to a fully secured wall. The necessity of floating walls is determined by site-specific conditions and local building codes, rather than personal preference. These walls are commonly found in basements located in areas like Colorado, Utah, and California, or any region with unstable or shifting ground. Without this space between the plates, upward movement of the concrete can force joists up, causing floors to buckle or tiles to break. Although DIY basement framing is possible, it is imperative to consult local building codes to ascertain whether floating walls are required in a particular area. The framing process itself is relatively straightforward and can be completed in a few hours, representing a small upfront investment that can prevent significant and costly problems in the future. Constructing a floating wall begins with selecting pressure-treated wood for the bottom plate, as it will be in direct contact with the concrete slab. This bottom plate is then secured to the concrete floor using concrete anchors, ensuring it is level and square to existing walls. Temporary 2-inch by 4-inch blocks are used to create the necessary clearance, typically matching building code requirements. Another 2-inch by 4-inch beam, serving as the floating plate, is placed on top of these blocks and secured to the pressure-treated plate with 6-inch nails after drilling pilot holes. Once the temporary blocks are removed, a top plate is installed by drawing plumb lines up to the ceiling joists on both sides and securing a 2-inch by 4-inch beam, ensuring it is perfectly plumb with the bottom plates. Finally, vertical studs are fitted snugly between the top and bottom plates, completing the floating wall structure. #FloatingWalls #HomeImprovement #StructuralStability #SoilMovement #BasementFraming #ConstructionTechniques #BuildingCodes #ConcreteFoundations