Block Wall Research Articles

Essential Anatomical Understanding to Achieve Successful Abdominal Wall Block

Essential Anatomical Understanding to Achieve Successful Abdominal Wall Block

Poster 249: Evaluation of ACL Reconstruction Using a Bone-ACL-Bone Complex Allograft in a Rabbit Model

Objectives:Anatomic anterior cruciate ligament (ACL) reconstruction is defined as the restoration of the native insertion sites, tissue dimensions, and collagen orientation. However, the microstructure and composition of standard tendon grafts used for ACL reconstruction differs from ligament. A bone-ACL-bone allograft (B-ACL-B) could represent a potential solution to ACL reconstruction, and thus the purpose of this study is to evaluate incorporation of a B-ACL-B graft used for ACL reconstruction in a rabbit model.Methods:Our study was approved by the Institutional Animal Care and Use Committee. A total of 71 New Zealand white rabbits were used, with 30 donor rabbits for harvesting bilateral B-ACL-B allografts, and recipient rabbits undergoing unilateral ACL resection followed by reconstruction with B-ACL-B allograft. Animals were euthanized for biomechanical testing (n = 14) at 4 and 8 weeks after surgery, and for micro–computed tomography (μCT), multi-photon microscopy, transmission electron microscopy (n=12), and histological analysis (n= 15) at 2, 4 and 8 weeks after surgery. Multi-photon microscopy analysis used Fast Fourier Transform in imageJ to calculate the proportion of fibers that deviated from orthogonal as a measure of collagen alignment and organization. One-way analysis of variance (ANOVA) with the post-hoc Tukey test was used to analyze differences among groups.Results:Gross inspection and radiographs confirmed intact ACL allograft in the proper anatomic position without evidence of complication. There was no significant difference between 4 and 8 weeks in mean failure force (4 weeks: 18.21 ± 8.74 N, 8 weeks: 21.75 ± 4.21 N, p=0.39) or stiffness (4 weeks: 8.08 ± 3.36 N/mm, 8 weeks: 10.88 ± 2.88 N/mm, p=0.15) for the B-ACL-B allografts. Progressive healing occurred between the bone block and the bone tunnel as demonstrated by a gradual increase in average bone-volume fraction (BVF) and total mineral density (TMD) between the bone block and tunnel wall in both femoral and tibial tunnels at 4 and 8 weeks. There was a significant decrease in TMD of both femoral and tibial bone blocks compared to day 0, indicating remodeling of the bone block (both p<0.001). Histological analysis showed bone block resorption at 2 weeks, followed by gradual new bone formation at the bone block-tunnel interface at 4 and 8 weeks. There was a gradual decrease in cellularity at the interface between bone block and tunnel wall (p=0.014), and increase in cellularity along the superficial aspect of the intra-articular ligament (p =0.008). Multi-photon microscopy demonstrated that the native control ACL demonstrated a mean % deviation from orthogonal value of 9.03± 1.81, 13.5±3.83 and 9.24±3.42 for femoral enthesis, mid-ACL, and tibial enthesis, respectively. The two-week specimens had a mean value of 6.50±3.34 (femoral enthesis), 10.4±1.73 (mid-ACL) and 10.97±3.666 (tibial enthesis) with none being statistically significantly different from control. The four-week samples had a mean of 9.10±1.87 for femoral enthesis, 8.39±3.28 for mid-ACL and 8.36±4.65 for tibial enthesis. Lastly, the 8-week specimens demonstrated that the mean deviation for the femoral enthesis was 7.26±1.67, mid-ACL was 7.89±1.58, and tibial enthesis was 10.8±2.55. The values for the mid-ACL was significantly less than controls at 4 and 8 weeks (p=0.0126 and 0.0063, respectively), suggesting maintenance of collagen fibril organization in the grafts. EM analysis of collagen fiber diameter demonstrated significantly lower average fibril diameter at all post-operative time points compared to age-matched native control ACLs (p<0.001).Conclusions:In conclusion, our rabbit model of B-ACL-B allograft ACL reconstruction demonstrates restoration of the normal macroscopic anatomy of the ACL, with progressive graft incorporation and remodeling. The B-ACL-B allograft, rather than a tendon graft, may provide the closest possible structural and biomechanical match to the native ACL, resulting in improved functional outcomes and may serve as a future option for ACL reconstruction. The results of this study provide important preliminary information to allow further study of this approach to ACL reconstruction and may serve as a baseline for future investigations.NoneFigure 1.Illustration of reconstruction plan for the B-Acl-B allograftFigure 2.Histolgy of interface and ligament.Figure 3.Results of TEM and MPM Analysis.

Is continuous Erector Spinae Plane Block (ESPB) better than continuous Serratus Anterior Plane Block (SAPB) for mitral valve surgery via mini-thoracotomy? Results from a prospective observational study.

ABSTRACTAims:Chest wall blocks are effective alternatives for postoperative pain control in mitral valve surgery in right mini-thoracotomy (mini-MVS). We compared the efficacy of Serratus Anterior plane block (SAPB) and Erector Spinae plane block (ESPB) on postoperative pain relief after mini-MVS.Settings and Design:It is a prospective, observational study.Material and Methods:A total of 85 consecutive patients undergoing continuous SAPB and continuous ESPB for mini-MVS from March 2019 to October 2020 were included. The primary outcome was the assessment of postoperative pain evaluated as absolute value of NRS at 12, 24 and 48 h. Secondary outcomes were assessment of salvage analgesia (both opioids and NSAIDs), incidence of mild adverse effects (i.e. nausea, vomiting, and incorrect catheter placement) and timing of postoperative course (ICU and hospital length of stay, duration of mechanical ventilation, ventilator-free days).Results:The median NRS was 0.00 (0.00–3.00) at 12 h and 0.00 (0.00–2.00) at 24 and 48 h. No significant differences were observed between groups. Postoperative morphine consumption in the first 24 h was similar in both groups (P = 0.76), whereas between 24 and 48 h was significantly less in the ESPB group compared with SAPB group, P = 0.013. NSAIDs median consumption and Metoclopramide consumption were significantly lower in the ESPB group compared to SAPB group (P = 0.002 and P = 0.048, respectively).Conclusions:ESPB, even more than SAPB, appears to be a feasible and effective strategy for the management of postoperative pain, allowing good quality analgesia with low consumption of opioids, NSAIDs and antiemetic drugs.

Grassholme Reservoir: northern embankment stabilisation works

Grassholme Reservoir is a large impounding reservoir commissioned in 1914 in the Lunedale Valley of County Durham. The most recent statutory inspection in 2016 resulted in a ‘Measures in the Interests of Safety’ (MIOS) recommendation to investigate and rectify a suspected unstable embankment slope between the reservoir and an adjacent watercourse. In November 2021, the stability works were completed to the satisfaction of the qualified civil engineer and the MIOS recommendation discharged. A total of around 20 000 m3 of selected clay fill was used to construct a reinforced earth slope with an interlocking concrete block wall at the toe. As a consequence of stabilising the northern embankment, the adjacent Carl Beck has been diverted through a buried pipe until realignment in spring 2022. The aim of this paper is to summarise and illustrate the various complexities associated with stabilising the northern embankment and realigning the existing watercourse, such as mitigating the loss of ancient woodland, managing complex ecological constraints and mitigating land access delays from the offset.

Performance on soil utilization model as interlock block wall material

Soil characteristics around Kendari City are included in the clay soil category. So far, clay has not been used optimally. Clay is only used as a pile material in buildings. The land around the city of Kendari can be made of brick interlock material. This research is important to be carried out to utilize the surrounding land as building wall material to obtain an economical and effective wall material. This study aimed to test the Land Use model's compressive strength and water absorption performance as an interlock block material in Kendari City. In this study, three treatments were made. Each treatment made 10 test specimens. Test specimens are made with a size of 25 cm x 12.5 cm x 10 cm. The research steps are preparing work tools, preparation of work materials, dry stirring process, moist stirring process, printing, drying, watering, testing, and data analysis. Data collection techniques are carried out in the laboratory. Testing includes compressive strength and water absorption. Based on the results of tests in the laboratory, interlocking brick from the ground has low compressive strength and water absorption. Interlock block can be used as a wall under the following conditions: first, the interlock brick material using clay is the same as the clay used by red brick material; second, interlock brick material from the soil is added with sand material.

Effect of resilient joints on the airborne sound insulation of single-leaf heavyweight constructions

The joint between a heavyweight construction and the surrounding building frame can be rigid or resilient. It is often believed that a resilient joint improves sound insulation. The purpose of this study was to investigate how the joint resiliency of a single-leaf heavyweight construction affects the sound reduction index and the total loss factor. A masonry wall of 10 m2 (220 kg/m2 calcium silicate block wall) was built three times (A−C) in laboratory using three different joint types between the wall perimeter and the test opening frame: A - All four joints rigid; B - Three joints resilient and one rigid; C - All four joints resilient. The sound reduction index was determined using both pressure and intensity method. The total loss factor was determined by measuring the structural reverberation time using hammer impacts. The sound reduction index reduced significantly with increasing level of resiliency. For joint type A, the weighted sound reduction index, Rw, was 50 dB while it was 45 dB for B and 43 dB for C. Correspondingly, the total loss factor reduced from A to C, i.e., with increasing joint resiliency. The effect of joint type was evident above the coincidence frequency (250 Hz) of the block wall. Resilient joint prevented the energy transmission from the wall to the building frame, which increased the sound radiation to the air, which was reflected as reduced sound reduction index. The results imply that the joints of a heavyweight construction shall be rigid if high sound reduction index is desired above the coincidence frequency. On the other hand, the increased joint resiliency improved the sound reduction index at most frequency bands below the coincidence frequency. Resilient joints around heavyweight construction can be beneficial in situations where the reduction of low-frequency noise is of primary concern.

BIM-BASED ENERGY PERFORMANCE EVALUATION OF A BUILDING ENVELOPE IN SEMI-ARID CLIMATE ZONE IN THE MIDDLE EAST

ABSTRACT The BIM building envelope integrates a BIM building’s internal and external environments, improving energy efficiency and substantially lowering energy usage. This research aimed to assess the energy efficiency of typical building envelope materials in Iran. To do this, we used Autodesk RevitR to generate a generic model and DesignBuilderR to conduct an energy analysis. The BIM building envelope integrates a BIM building’s internal and external environments, improving energy efficiency. A BIM building envelope energy analysis was performed on 58 local wall constructions material in Iran. Then, the energy consumption of a BIM building’s HVAC system was then compared against the costs of all external wall alternatives to determine the optimal layer combination. Consequently, the energy simulation results demonstrated that the double external wall structure, 2AAC block core, with XPS (CFC) insulation exterior wall and the single external wall, PERLEX Ultra-Lightweight (PUW) wall performed better. In addition, the clay block wall is found to be the optimum solution for the case study location. The applicability of the proposed system is validated with a case study of a traditional residential building.

Ultrasound Guided Regional Anesthesia in Thoracic Surgery

Perioperative analgesia plays an important role in thoracic surgery, regarding not only patient satisfaction, but also in preventing postoperative complications such as pneumonia. Ultrasound-guided thoracic wall blocks close the gap between opiate based and neuraxial pain management concepts.The following article explores the different ultrasound-guided approaches to anesthetize the thoracic wall, ranging from the ventral blocks such as parasternal or PECS I/II, followed by the lateral blocks (i.e. serratus anterior), up to the dorsal approaches including the paravertebral, erector spinae plane, and retrolaminar block.In summary, the anterolateral blocks are supplementary blocks in an opiate sparing, multimodal anaesthesia concept, whereas the dorsal procedures, as they include visceral anaesthesia, are an alternative to neuraxial anaesthesia, as they have a comparable analgetic potency. For minimally invasive thoracic surgery, where due to risk-benefit considerations epidural anaesthesia is omitted, thoracic wall blocks can be utilized in a single shot or a continuous, catheter-based approach.

Restoring force model of steel‐recycled concrete composite frame with infilled recycled block wall

SummaryTo study the restoring force model of steel‐recycled concrete composite frame with infilled recycled block wall, the experimental results of two recycled concrete‐filled steel tube frames with infilled recycled block walls and three steel‐reinforced recycled concrete frames with infilled recycled block walls under low cyclic loading were analyzed. The four broken‐line skeleton curve model which was suitable for this kind of composite frame was proposed, and the calculation methods for different stages of the skeleton curve were given respectively. According to the hysteretic characteristics of different frame specimens, the hysteretic loops for steel‐recycled concrete composite frame with infilled recycled block wall were simplified by using the treat methods of positive and negative symmetry and sudden drop of bearing capacity, and the restoring force model for different type of steel‐recycled concrete composite frame with infilled recycled block wall was established. At the same time, combing the experimental results, the proposed restoring force model was verified. The results show that the established restoring force model can predict the hysteretic behavior of steel‐recycled concrete composite frame with infilled recycled block wall well, and it can provide theoretical support for the elastic–plastic time history analysis of this kind of frame structures under earthquake.

A NEW CONFIGURATION OF ROOF SKYLIGHT COMBINED WITH SOLAR CHIMNEY

This paper reports experimental performance of a new modular configuration of roof integrating skylight and solar chimney intended to reduce heat gain admission, induce ventilation and ensure sufficient indoor illuminance. This integrated Skylight Solar Chimney (SSC) configuration is composed of three layers: a 1mm thick clear acrylic layer on the outside, a set of 1 mm thick aluminum slats distanced each other at the middle and a layer with a combination of clear acrylic and aluminum slats at the inner side. To assess SSC performances, two small rooms of 2.52 m3 volume were built using concrete blocks for walls and corrugated cement panels for the south facing roof slopped at 30 degrees. The roof of the first house, which served as a reference, integrated a transparent corrugated panel whereas the other house integrated our SSC. The dimensions of the SSC are 0.50 m x 1.50 m x 0.15 m (W x L x H). A 0.025 m2 outlet opening was located at the top lateral side whereas two inlet openings of similar surface area were installed on the bottom lower layer (one inside the room and another outside). Field test results showed that in all scenarios considered the indoor temperature of room with SSC was 1 to 4 °C lower that of the reference room and varied following ambient conditions. When both inside and outside inlet openings were used, the highest temperature difference was observed. The measured heat flux through the roof of reference house was much more important than all SSC scenarios, a 50% difference was observed when both SSC inlets were open. This clearly demonstrated SSC efficiency to reduce heat gain. The air change (ACH) induced varied between 2 to 29. SCC indoor illuminance was about 50% lower than that of the reference house.

The Role of Maximal Locoregional Block in Autologous Breast Reconstruction.

Enhanced Recovery After Surgery (ERAS) has become the standard of care in microsurgical breast reconstruction. The current literature provides overwhelming evidence of the benefit of ERAS pathways in improving quality of recovery, decreasing length of hospital stay, and minimizing the amount of postoperative narcotic use in these patients. However, there are limited data on the role of using maximal locoregional anesthetic blocks targeting both the abdomen and chest as an integral part of an ERAS protocol in abdominally based autologous breast reconstruction. The aim of this study is to compare the outcomes of implementing a comprehensive ERAS protocol with and without maximal locoregional nerve blocks to determine any added benefit of these blocks to the standard ERAS pathway. Forty consecutive patients who underwent abdominally based autologous breast reconstruction in the period between July 2017 and February 2020 were included in this retrospective institutional review board-approved study. The goal was to compare patients who received combined abdominal and thoracic wall locoregional blocks as part of their ERAS pathway (study group) with those who had only transversus abdominis plane blocks. The primary end points were total hospital length of stay, overall opioids consumption, and overall postoperative complications. The use of supplemental thoracic wall block resulted in a shorter hospital length of stay in the study group of 3.2 days compared with 4.2 days for the control group (P < 0.01). Postoperative total morphine equivalent consumption was lower at 38 mg in the study group compared with 51 mg in the control group (P < 0.01). Complications occurred in 6 cases (15%) in the control group versus one minor complication in the thoracic block group. There was no difference between the 2 groups in demographics, comorbidities, and type of reconstruction. The maximal locoregional nerve block including a complete chest wall block confers added benefits to the standard ERAS protocol in microvascular breast reconstruction.

Assessment of sandcrete hollow blocks’ thermal performance as a walling material for tropical buildings in Lokoja, Nigeria

PurposeUnderstanding the thermal performance of sandcrete hollow block walls in the tropic is very essential for occupants' well-being, productivity and efficiency, due to its widespread application in buildings in the study area. Lokoja, in Nigeria, lies in the warm humid zone with its attendant's high temperatures all year round. Thus, providing an acceptable walling material that will control the high indoor air temperature becomes imperative. This paper assessed sandcrete hollow blocks as a walling material used in Lokoja, to determine the thermal performances for effective thermal comfort of the residents.Design/methodology/approachIt involves the construction of a habitable model building with the commonly available sandcrete hollow blocks in the area. One unit of Cryopak iMINI Temperature and Relative Humidity Data Logger called new generation intelligent iMINI with Serial Number and Product Code MX-CI-145–0009 and MX-HE-S-16-L was installed, to record the indoor air temperature and relative humidity data at an interval of one hour, for 12 months covering dry and wet seasons. The results of the recorded data were downloaded to an excel spread sheet for assessment and analysis throughout the seasons. The values were computed using the temperature–humidity index (THI) equation, with a view to determine the indoor thermal comfort level category.FindingsThe study revealed that sandcrete hollow block walls provide thermal discomfort of the indoor environment for both seasons, with attendant adverse effects in the comfort of the occupants. The paper concludes that proper orientation of buildings, planting of trees, use of low absorbing or reflective surface materials, application of cavity walls to receive insulation materials in between the hollow spaces provided, instead of the single walling as well as providing shading device elements, can improve users' comfort and also ameliorate the heat effect on the external surface of building transferred into the interior by conduction, radiation or convection within the area and in the tropics at large. Other thermally eco-friendly wall materials available in Lokoja includes timber, stabilized laterite–cement blocks, burnt bricks and earth-mud bricks which can be used to replace sandcrete hollow block walls. These alternative wall materials are used for construction of residential and office buildings by the colonial government of Sir Fredrick Lugard in the study area.Practical implicationsThe application of sandcrete hollow blocks as a wall material is in vogue, not minding its thermal discomfort to the users and the environment; this is due to its availability and ease of production. The acceptability of this walling material requires holistic study to unravel the best way to reduce the thermal discomfort inherent in its application.Originality/valueThe author succeeded in revealing the thermal performance of sandcrete hollow blocks as walling material in Lokoja, the study area. It is a first attempt at understanding the performance for human comfort in the area. This will greatly assist the resident and other researchers to improve on the application of sandcrete hollow blocks as walling material towards ensuring that maximum indoor thermal comfort is achieved.

Feasibility experiments of seismic concrete block walls without joint mortar

The authors developed two types of block systems consisting only of main block and key block without joint mortar in consideration of seismic performance and workability. Two types of block systems have different key block shapes: One is the peanuts shape and the other is the dumbbell shape. In this study, the proposed two types of block walls as well as a typical block wall were experimentally investigated to evaluate the seismic performance. In the tests, full-scale, single-story specimens were tested under static cyclic in-plane loading, and failure patterns and cracks were carefully observed. In this paper, the loading bearing capacity, energy dissipation capacity and reuse ratio of block walls are discussed in detail. As a result, the deformability, energy absorption capacity and reuse ratio of the proposed block systems were considerably higher than those of typical block system.

DEVELOPMENT AND MATERIAL OPTIMIZATION OF 0.67HP PETROL GENERATOR CYLINDER BLOCK USING TAGUCHI DESIGN AND FINITE ELEMENT ANALYSIS

The development of 0.67Hp gasoline generator cylinder block and the material optimization of the component using Taguchi Design and Finite Element Method were carried out successfully. The cylinder block is known to create an avenue for the piston to carry out its reciprocating effect on the crankshaft for onward transmission for the machine output. The designed cylinder block had an engine power of 5.11kw which drove piston through a bore and stroke length of 46.10mm and 51.20mm respectively. The determined clearance volume of 9.46cm 3 was contained in a cylinder wall thickness and block length of 3.04mm and 58.88mm respectively. The designed values were found to be in consonance with recommended values obtained in standard engineering text. The developed mathematical model was determined to be adequate with a statistical Coefficient of determination (R 2 ) of 98.62% and the Adjusted coefficient of determination (Adj R 2 ) was found to be 97.79%. The comparison of optimal values developed from the Taguchi design and genetic algorithm optimizations showed that obtained values from both methods were noticed to be very close as only a difference of about 0.0005 existed among the input parameters. The genetic algorithm result was seen as a kind of validation for the Taguchi design optimization. The Finite element analysis result showed that the temperature output result recorded the highest temperature of 100 o C around the cylinderical bore axis while the lowest temperature of 51.97 o C was found on the cooling fins of the component. Keywords: Optimization, Taguchi Design, Genetic Algorithm and Finite Element Analysis. DOI: 10.7176/JIEA/12-1-04 Publication date: March 31 st 2022

Comparison of ultrasound-guided transversus abdominis plane (TAP) block and quadratus lumborum (QL) block in inguinal hernia surgery.

Comparison of ultrasound-guided transversus abdominis plane (TAP) block and quadratus lumborum (QL) block in inguinal hernia surgery.

Performance behaviour of agro-waste based gypsum hollow blocks for partition walls

Crop residue management is a massive problem in the agriculture sector. Agricultural waste in the form of stubble which is usually burnt in the farm fields, causes severe air pollution and poses a threat to the environment. The present study investigates the addition of agro-waste (rice straw) in gypsum hollow-core blocks for partition walls. Various compositions of agro-waste-based gypsum samples have been studied for compressive strength, thermal, sound absorption, sound transmission loss, and fire-resistant properties. The addition of rice straw in gypsum reduces the density and compressive strength of the test sample, thus making it lightweight for non-load bearing wall application. The thermal conductivity of the rice straw added gypsum samples show a decrease in thermal conductivity from 0.2 to 0.11 W/m K. Acoustic properties viz., noise reduction coefficient (NRC) increases from 25 to 45% with increase in rice straw addition and a decreasing trend in sound transmission class (STC) from 37 to 28 dB. The fire-resistant properties viz., surface spread of flame, and fire propagation index test have shown good fire-resistant properties. The agro-waste-based hollow gypsum blocks may be used as a promising material for drywall partitions owing to its thermal insulation, low density, good acoustic and fire-resistant properties.

The Crete Isl. (Greece) Mw6.0 Earthquake of 27 September 2021: Expecting the Unexpected

The 27 September 2021 damaging mainshock (Mw6.0) is the first known strong earthquake that ruptured the Arkalochori area, Crete Isl., Greece, during the entire historical period, making it an unexpected event in the long-term sense. The area is characterized by the presence of the normal active Kastelli Fault (KF) striking NNE-SSW and dipping towards ~WNW. The KF, of surface exposure only ~6 km, at its southern tip is truncated by the nearly perpendicular active Nipiditos fault. The main shock was preceded by foreshock activity lasting for ~3.9 months, thus the mainshock turned out to be an expected event in the short-term sense. Maximum ground subsidence of ~20 cm was estimated from InSAR images, but this also incorporates deformation that may have been caused by the largest aftershock (Mw5.1) of 28 September 2021. The fault model produced from the inversion of InSAR observations indicated strike 216°, dip towards ~NW at angle 53°, rake −95°, and is consistent with fault-plane solutions obtained from routine moment tensor analysis. The geodetic seismic moment calculated from the Okada’s formalism is 1.14 × 1018 N·m (Mw6.0), while a maximum slip of 1.03 m was found at depths from 3.5 km to 5 km. The entire aftershock epicenters cloud strikes in a ~SW-NE direction but is distributed in two clusters, the southern and the northern ones. The foreshock cloud, the main slip patch, the deformation area, and the strongest aftershocks all fall within the southern cluster. The foreshocks concentration at the deepest edge of the main slip patch was a foreshadow of the mainshock nucleation area. The northern cluster, which is very likely due to the gradual expansion of aftershocks, is situated in the KF hanging wall block. To interpret the main seismic slip in the southern cluster area we propose the existence of a buried KF segment at the SSW-wards prolongation of the emerged at the surface segment. Assuming a rectangular seismic fault stress drop Δσ~7 bars was found. However, for a circular fault area, which in this case is more realistic, we get Δσ = 55 bars. This is a relatively large value for Greek earthquakes but is explainable by increased fault rigidity as a result of the long repeat time of strong earthquakes in KF.

Shaking Table Test of a New Type Insulation Decorative Block Wall under Out-of-Plane Loading

In order to solve the problems of complex construction, poor weather resistance, and environmental pollution of conventional thermal insulation materials, this paper introduces a new type of insulation decorative block (IDB) filled with insulation materials. Different anchoring methods were adopted to study the influence of anchor bolts on the out-of-plane mechanical properties of IDB walls. The test results revealed that the anchor bolts could effectively prevent the appearance and development of cracks in the specimens. With the increase of anchor bolts, the acceleration and displacement of the IDB walls decreased. Compared to rectangular arrangement, the staggered pattern of anchor bolts could reduce the relative displacement and acceleration. The structural calculation of IDB walls was carried out to determine the number of anchor bolts at different heights, and design suggestions were given to improve the performance of IDB walls. The analysis and test results indicated that the IDB is suitable for application in engineering structures.

DESIGNING A TRAPEZOIDAL MODULAR BLOCK WALL WITH NONLINEAR OPTIMIZATION

A rectangular wall is better in terms of stability and ease of calculation than a trapezoidal wall. However, a trapezoidal wall is sometimes inevitable such as a retaining wall construction near rockface. FHWA provides simplified rules to design a trapezoidal wall. However, FHWA does not give an example to follow, and the rules need trial and error to implement. BS8006 gives an exact dimension of the block heights, but designing still needs to adjust the block widths. A 16-meters high modular block wall project near rock face in Thailand as an example to illustrate a calculation detail in external stability checking follow FHWA simplified rules and BS8006. The illustrations are trapezoidal walls with two zones, three zones, and four zones. Nonlinear optimization models are also used to minimize the wall base length to facilitate the construction instead of jacking the near rock face to build a rectangular wall. Optimization models also help to relax FHWA simplified rules and BS8006 guidelines. Using an optimization model can decrease the base length from 0.7H to 0.6H for a rectangular wall or even 0.5H for a rectangular wall with competent foundation soil. Optimization models can also achieve a base length down to 0.48H with a decrease in the cross-sectional area down to 0.92 for a three zones trapezoidal wall. A simple three zones wall with exact dimensions is also proposed in the competent foundation soil conditions.

Out-of-Plane Structural Performance of Compressed Earth Block Walls Subject to Quasistatic Loading

Abstract This study constitutes a step forward in the overall effort to evaluate the applicability of compressed earth blocks (CEBs) as an environmentally friendly construction alternative in Kuwait. The study is part of a series of experiments that started by assessing different soil samples from various regions in Kuwait. It was discovered that soils in the northern areas (near Al-Sabriyah district and Boubyan Island) contain a good mixture of clayey and silty deposits that can be used to produce CEBs. The collected soil from this region was used in producing CEBs. Three half-scaled walls were constructed and were laterally tested in the out-of-plane direction using quasistatic loading. One of these walls was strengthened using carbon fiber reinforced polymer (CFRP) laminates. A fourth wall made from regular concrete masonry units (CMU) was also tested and compared with the results from the CEB walls. The tests showed the latter had a significantly reduced lateral capacity compared with the wall made from CMUs. It emerged from the test results that a higher percentage of stabilizer in the CEB production enhances the performance of walls made from these CEB in their out-of-plane direction. This is especially the case in terms of stiffness, strength, displacements, and energy dissipated. Results revealed that strengthening CEB walls can alter their structural behavior from flexural dominated to shear dominated failure with an increase of 116 % in the wall strength (nearly doubled) under lateral loading in the out-of-plane direction.