a b s t r a c tRetrofit of existing steel buildings often requires strengthening of the connection regions. One common connection, the bolted beam-column connection, is often strengthened in design using stiffened extended endplates, or with continuity plates welded between the column flanges. In a retrofit scenario, adding stiffeners to the endplate is difficult due to the concrete slab and metal deck, and excessive field welding of continuity plates may be uneconomical. Simplifying retrofit efforts, and for economy, connection strength may be improved by simply adding more bolts to the connection. Current code methods, broadly generalized to all connection configurations, are currently based on component experiments having only one bolt on either side of the column web. This study experimentally investigates strengthening of bolted beam-column connections, having no column web stiffeners, using more than one bolt on either side of the column web. Six full-scale bolted beam-column connections are tested, representing exterior beamcolumn connections (beams attached to only one column flange). Connections with both extended and flush endplates are considered. Two column sections (HE300A and HE300B) are tested along with HE300B beams creating both equal-column-beam, and weak-column strong-beam scenarios. Analytical simulations provide insight into local connection demands, and experimental results are compared with current code methods. The experiments indicate that closer inner-bolt spacing relative to the column web increases connection moment capacity but decreases rotation capacity (connection ductility) due to increased bolt prying forces from column flange distortions. The outer bolt of multiple-bolt-per-row configurations contributes very little to the connection resistance when column web stiffeners are not considered. With the exception of specimen T-3B which failed through bolt-thread shear after 0.02 rad, all connections with multiple bolts per row still achieved rotations greater than 0.06 rad. The Eurocode 3 component method and adapted Eurocode 3 procedures conservatively predicted the connection strength of each test specimen, including weak-column strong-beam assemblies, and accurately identified the initial connection limit states.

Due to steep terrain and fast flowing rivers in the Himalayan region of Nepal, medium to mega size hydropower projects are constructing day-by-day. Tunnel is one of the best and short routes for water conveyance system for power production. Hundreds of kilometers of tunnels have been constructed and new tunnels are planned in this region. The availability of high head for hydropower generation, the tunnel cross sections are relatively small, up to 6 m diameter in size, and there is high rock cover above the tunnel alignment. This paper focuses on the design and construction practices of hydropower tunnel passes through weak rock mass with high rock cover of the Himalayan region of Nepal. Most of the hydropower tunnels undergo excessive deformation and support failure during the tunnel construction, which delayed the project as well as increases the cost of project. The paper first discusses the available construction practices for tunnel and underground structures. In the second part, the current practice employed during construction in the Himalayas is discussed along with the shortcomings of the methods and how it is addressed in the region.

This study focuses on the design and stability analysis of underground structures in the Lesser Himalayan Region of Nepal. The rock support design for such opening depends upon the rock mass strength. In this study a proposed Kathmandu University Geo-Lab tunnel and cavern, which passes through weak rock mass conditions, was used as a case study. Existing empirical and analytical methods for the stability of the proposed tunnel and cavern are used for the estimation of support pressure and design support. A detailed numerical study was carried out in 2D finite element analysis to design the tunnel in such region. The results of analysis showed that the support pressure and deformation can be predicted very well from the numerical analysis.Kathmandu University Journal of Science, Engineering and TechnologyVol. 13, No. 1, 2017, page: 1-19

This paper is focused on the assessment and numerical analysis of hydropower tunnel of the Lesser Himalayan Region of Nepal. This region lies between two major faults namely Main Boundary Thrust (MBT) and the Main Central Thrust (MCT) with weak rock mass like phyllite, schist, gneiss, phyllitic schist, etc. Thus, to overcome the stability problems during underground construction, proper rock support system must be installed. Rock mass classification systems are commonly used for estimating the rock support system in this region, but this approach is inadequate to address the underground stability problems. In this study, numerical analysis is done to define the requirement of support and the result compared to actual support provided in selected case study. Analytical approach is used along with two-dimensional Finite Element Analysis using the software, RS2 provided by RocScience for the study. Finally, required modification of the provided support has been suggested to overcome the problem faced in the selected tunnel.

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